Home Battery Storage is a Bad Financial Investment in 2024?! Octopus Energy Smart Tariffs FTW!

[@SimonRGates]

It will depend on your usage, for certain, and bearing in mind when we did our installation, the octopus tracker rate was averaging 36p, so predicting what prices will be in the future is not easy. Our consumption is: 160kWh / week house, 50kWh / week car. If we didn't have solar & batteries, that would be £2300/year for the house £700 for the car @ today's 28p/kWh. We have enough batteries to provide almost all our house power, so with Intelligent Go @ 7.5p/kWh, it would instead be £600 for the house, £200 for the car. So the batteries would save us £1700/year over standard rates. VAT is meant to be lifted on batteries from next month, and this would make our battery stack cost £4200, or 2.5 years worth of savings. Obviously there's the inverter to add, and the electricians time - the inverter & battery installation took a morning's work of the 4 day solar install, so it can't be that expensive. Say the whole thing would have cost £6000 - 3.5 years to break even. The batteries should be good for 6000 cycles / 15 years... apparently... With solar, it's a bit trickier to work out the benefits. For 4 months of the year we run 90% on overnight rates, for 4 months of the year we run 90% on solar, and for the rest of the time I use a solar prediction to charge the batteries to make up for what we don't generate. The solar install was by far the least cost effective part of what we did, with a repayment time of 6-7 years, and of course it makes the batteries less cost effective too because you're using them less. However, with all of that, our electricity including standing charge and export repayments, costs £300/year - over £2700/year saving, giving 5 year breakeven against 28p standard rates and VAT free battery prices.

[@ecoterrorist1402]

the easy way to look at the use, look at your smart meter readings, most standard customers use avg 8kwh per day with a summer avg 4-5 kwh & winter 10-15kwh that's a good marker anyway

[@EverydayLife621]

I think we are on par with this also - over £3k/year saving, giving 3-5 year break even

[@ecoterrorist1402]

@@EverydayLife621 what ever is and was your kwh use, as 3k is a massive ammount

[@andyballard1883]

The other aspect with the Battery stack is that you can take it with you very easily if you move. I think what is needed for to to become mainstream though is for the Utility companies to commit to their cheapest off peak tariffs being the same percentage below the standard rate for a period of say 5 years. This would ensure that you would see the return on your investment materialize and not be scuppered by the companies just removing their off peak tariffs and price gouging once there is enough adoption.

[@ecoterrorist1402]

@@andyballard1883 I agree, shame the real deals are EV based only, YET another we would like your money Big six, some offer lower rates, but EV rates are cheaper

[@gp7255]

Having Home Battery Storage (HBS) as part of my solar system has allowed me to almost cap my grid usage at 7.5p/kWh. My system is a 5.2kW solar array, 5.2kW hybrid inverter, 10.2kWh battery, and Intelligent Octopus Go tariff. I have shifted the heavier loads such as EV charging, HBS charging, and dishwasher to run between 11:30pm and 5:30am when my import rate is 7.5p/kWh. I charge my HBS to 100% every night so that I start every morning with a full HBS. My baseline consumption is between 400W and 500W, with occasional spikes during the day from the electric jug, microwave oven, toaster, oven & grill, etc. During winter days, the limited solar generation usually suffices to cover my baseline consumption, with any shortfalls being met by the HBS (as long as I'm not using multiple high power appliances at the same time, otherwise the grid kicks in at a much higher rate). On the other hand, during summer days, both my baseline consumption and spikes are met by solar generation, with the HBS remaining more than 95% charged for a greater part of the day, and all the excess solar generation being exported (currently at 15p/kWh). Thus, that way, I'm ensuring that 99% of the electricity that I import is at 7.5p/kWh, while simultaneously maximising my export payments.

[@turingtrading5301]

Best approach based on current payments, do the same but with a 13.5kw battery /5k inverter setup.

[@dancingfrogsxb1276]

Gonna do similar now we have another 5kwh battery puts us at 10kwh and we use between 7 & 10 per day so should be good.

[@laurencedamazer2260]

Totally agree with you. Fed up people saying get as much battery storage as possible. I generate 5,000kwh, use 4,000kwh and export 3,500 kwh p.a. My total savings are £1,200 p.a. with a 6kw array & a 5kwh battery (battery costs £3,000). Battery discharge is 1,500kwh p.a. So max. possible savings from use of battery is about £450, if all savings at peak rate. ( Unlikely, more like £250.) This ignores export savings of about £500 p.a.. If got a second 5kwh battery, £3k, lucky to save another £200. It might be viable if had the super cheap EV rates, but no EV. It really all depends on personal circumstances.

[@UpsideDownFork]

Exactly that! I went into the numbers in greater detail in this follow up video: kzbin.info/www/bejne/nommmo2tobmooZIsi=1FFSHcL1fANN_Xni

[@mwnciboo]

Get Solar panels - pay them off - then get a battery in 5 years... you cannot use when you are not generating - you end up buying back. Your own generated kWh at X3 the price... There is a DELTA on what you generate and buying back from the Grid e.g it is costing you 2:1 or 3:1 in credit of kWh to debit 1Kwh back. You are 100% right on circumstances but battery systems can be used to generate income without solar panels simply on time charging/ discharging on a variable tariff. I have a 2011 solar 3.2kwh system with a battery 13kwh - the system has kept trucking energy kept going up - during start of Ukraine war my battery paid itself off as energy sky rocketed. Never under-estimate our voracious appetite for energy. My FITS basically offset what I paid for the battery and the war paid it off in 24months. Now I am in optimisation - e.g Air source - better newer panels.

[@peterparker9997]

Hi, I've only recently found your channel but have subscribed as I like your common sense approach. I'm in the fortunate position of having: Solar PV (5.5KW system on a due south facing roof), a Tesla Powerwall 2 battery (13.5KWh of storage), a Zappi EV charger (charge the car on sunshine in brighter weather) and an electric car BMW i3 Range Extender. I've had this set-up since July 2018, so a good period of time to get plenty of experience this the system. I'm on Octopus Intelligent Go tariff, which either fills the car battery up overnight when needed or fills the Tesla Storage battery up, if the Powerwall thinks the weather for the day ahead isn't going to be favourable. Obviously in the summer months there's an abundance of energy being generated from the solar roof and the Powerwall 2 is often completely filled by Solar electricity long before midday. However, in the darker months (winter) with the limited solar generation and the Tesla battery filling up with low priced electricity overnight, we can go for most of the day on the stored (cheap) electricity but we cannot make it through the entire day without drawing some of the more expensive electricity from the grid. Therefore, if you do consider going with battery storage I can understand why people are saying to get as much storage capacity as you can afford. I'd love a 2nd Powerwall 2 but even with the 0 Vat at the moment it's still quite an investment. It would mean however, that we could use nothing but low cost electricity all year round. The other thing to consider that will become commonplace, probably within the next 12-18 months, are EV's with 'Vehicle to Home' and 'Vehicle to Grid' becoming more widespread. The question then becomes do I invest in static battery storage or in an EV that can provide battery storage when not being driven around!

[@UpsideDownFork]

Thanks for the comment! Sounds like you've got an excellent setup there! When the V2G trials started rolling out in 2021/2022, I was hopeful that big progress would be made. Then the CCS V2G trials came in 2023 and I hoped another step forward. Unfortunately, the more I research it, the further away I believe it to be. Lack of standardisation in connectors and protocols is just one barrier. Some manufacturers believe the bi-directional inverter should be in the car whilst others think it should be in the home. I think we're still several years of fragmented market rollout before we see mass adoption. I try and hold out hope though!

[@1240Connor]

I came to a similar conclusion regarding a home battery with our solar, given we have 7p overnight import and 15p export. However the main caveat is those rates will undoubtedly change in the future and could become more favourable overnight for local storage and consumption of solar energy rather than exporting. When you're looking at 10+ years return for a home battery it's impossible to know how import and export pricing will change in that time. Also looks like 0% VAT for MCS battery only installs is being implemented soon making it much easier to go with solar now and add on a home battery in the future if the economics change to favour it

[@CrazedCrittic]

^ This: If you "invest in renewables, it should be because you want to remove grid costs not reduce them temporarily at this time. Solar PV/battery gives you effective independance if sized correctly.

[@UpsideDownFork]

@@CrazedCrittic That's a great point!

[@UpsideDownFork]

Thanks for the comment. I make some very large assumptions in my basic calculations and you rightly point out the biggest, we don't have a crystal ball into the future pricing models. This is the strategy i'm currently leaning toward as we head into summer. Fit solar now with a hybrid inverter, see what happens in the battery market and if the prices tumble as predicted. Possibly add a home battery in October/November.

[@terrancedactielle5460]

I get that but you pay no VAT on batteries or a car charger if installed at the same time.

[@OVB_NL]

We have a Powerwall and 2 EVs and are on (Intelligent) Octopus Go. Even with our EVs, 97% of all our imported electricity comes from the off-peak tariff thanks to the battery. If you don't have EVs and you have a 15kWh battery, I recon you could achieve over 80% of all electricity imports from off-peak rates (3 bed house incl one of us working from home). The battery for us has been a no-brainer. Another aspect is that since a few months ago, the solar export tariff has been increased to 15p/kWh...and our off-peak import is 7.5p/kWh. This means you can also use the battery to make some pretty decen additional revenue just by charging at night and discharging in the day when prices are high....might be worth looking at modelling this also but less certain that that will be available over the coming 10 years.

[@UpsideDownFork]

Thanks for the comment. Great to hear of your success. Unfortunately this strategy won't work for us with a heat pump. More info coming in my next video!

[@edwardwilcox8982]

Have you allowed for the electricity price inflation. Even 1% inflation is significant due to compounding. I calculated my FIT solar payback times as 10 years, but it turned out to be 7.

[@UpsideDownFork]

Thanks for the comment! For the sake of these basic calculations, I have ignored inflation. Does your FIT solar array also generate more than your original forecast shows?

[@edwardwilcox8982]

@UpsideDownFork The "fitters" calculated I would receive 7% less than the maximum of 3.9kw, and they were roughly correct. It generated 3.7kw on 1 day a year up to last year when the array produced 3.6kw on the maximum day. 4.3Mw in 2014 falling to 3.8Mw last year. I suspect its average now is 3.9 to 4Mw. So deteriorates about 1% a year. I am receiving 24p/kw now from 14p/kw then, so it will double in 12 years and then double again.

[@geralddavison]

This is my thoughts exactly. None of people doing these calculations have any allowance for inflation or price volitility. Over the decades there seems to have been talk of "reduceding bills" due to improvements in technology.... but it simply never happens.

[@UpsideDownFork]

@@geralddavison what do you think about my follow up video? kzbin.info/www/bejne/nommmo2tobmooZI

[@geralddavison]

@@UpsideDownFork a lot more included, which is always better. I take my hat off to you for putting these calculations out there because there are so many possible variables that people will bring up - it's a bit like asking 5 economists for a future forecast, you will get 20 answers 🙂 I still think inflation is important. Especially as you have included a "cost of funds" calculation which includes potential future interest returns. We are a two EV house, combined 15,000 miles a year. Octopus Intelligent currently, although I have been on Agile (pre Ukraine invasion!). No battery, solar or heat pump at the moment. I will factor in some of your calculations. Both videos are good "make you think" pieces which will make me re evaluate my own numbers. Thanks

[@johnrush3596]

Great video. We are 5 years on with 10.6kw Solar Edge inverters for solar and Lux for inverters. We use Pylontech batteries for the storage, and these get mounted in a server rack. From a load shifting point of view, between march and end september/beginning of october, the batteries are used to provide power from when the sun goes down to when it comes back up. Outside of these month, we use octopus go to charge the batteries overnight and use them as much as possible during the day. This setup has kept our yearly bill to around 2k with the house consuming 14MWh. The item to remember with batteries is there is a 10 to 15% round trip loss for AC coupled or AC charged and around 8% for DC coupled (aka charged from solar). 48v makes great sense for most applications, but as has been seen with electric vehicles there is a lot of logic in higher voltage as the losses are less and the cables are thinner. Look at Fox ESS as that is using high voltage and it means the power from the panels (running at 300 odd volts DC) needs less conversion to be stored in the battery. The same is true for any AC power being pushed into the batteries. The price on the FogStar unit is suprising. 3x US5000 5KWH batteries at the moment would be 1k each ex vat. You have to wonder what the catch is.

[@UpsideDownFork]

Thanks for the great comment! 14MWh is no joke! I think i'll take the conversion loss issue into my next video.

[@wajopek2679]

@@UpsideDownFork don't forget to factor in some battery degradation capacity reduction so after 10yrs you won't be storing as much.

[@davefroman4700]

There is no catch. The cost of LiFePo4 batteries has crashed over the last year in China. And that is where 90% of them come from. Last I heard it was approaching $80/kWh.

[@UpsideDownFork]

@@davefroman4700 Thanks for the info!

[@simonperkins345]

I started my journey in 2011 with solar panels 2016 Nissan leaf came along 2022 battery storage 9.5 kw givenergy 2023 A2A heat pump Gas was disconnected. 2024 I hope to install a IHP Mixergy hot water tank and maybe another 9.5 battery and move onto octopus intelligent what a journey i am enjoying every minute of it.😊

[@UpsideDownFork]

Thanks for your comment! So solar panels were your gateway drug into renewable technology! Mine has been the heat pump but now i've got the bug!

[@simonperkins345]

Yes it just grows and grows think I am near the end now!!! It has become a lifestyle change that we have invested in. We also insulted all the external walls internally with celotex before we put the A2A in. Once the outside temperature gets above about 7 degrees we use very little heating.

[@fyank1]

Had my PW2 installed in July and all my home consumption is now at 7.5p per kWh as is charging my EV. But the biggest advantage for me is the back up capability in a power outage. Last night we had a two hour outage and were the only house in the area with power. You can’t put a price on that and it’s the second outage we have had since install. Energy security is priceless.

[@UpsideDownFork]

Thanks for the comment. Where in the country are you located? I think we're fortunate that we never get power cuts here.

[@fyank1]

@@UpsideDownFork I live in South Cheshire and we’ve had about 8 power cuts in the last 6 years, some for several hours at a time.

[@UpsideDownFork]

@@fyank1 Ouch. We've had 1 brief one in the last few years. I know when they are because my NAS sends me an email when it's been offline!

[@evanleebodies]

I assume you had the EPS (emergency power supply) option fitted during installation. The EPS option isn't always part of the installer package.

[@dancingfrogsxb1276]

Do you need a special set up so it kicks in when the power goes down?

[@andyballard1883]

if you divide your 5500 KW/H annual usage by 365 it comes out at 15.07 which in theory means you would have enough in that 15.5 KW/H home battery to cover all your usage. They key seems to be if you can fully charge it during the overnight offpeak window then you have no need to load shift your bulk household electrical activities. I'm making and assumption that the installation of a battery is a lot less work than a solar array and therfore the cost for installation should be less than the £2,500 you estimated so I could easily see a possible payback in 5 years. There is also the fact that if you moved house you could take the battery with you easily and refit it.

[@UpsideDownFork]

Thanks for the great comment! Because of the recent installation of our heat pump, we will have more of a pronounced V shape usage profile than most. Using substantially more energy in the winter than the summer. We would need 25kWh to see us through a typical winter's day so far. Some of the extreme cold days would need 45kWh of battery, but we'll just discount those anomalies. Realistically, 2 x 9.5kWh GivEnergy batteries would be a sensible balance between capital cost and usable storage for much of the year. Having 2 of those installed, with the inverter etc comes to around £7000. That starts to make the payback look more challenging.

[@andyballard1883]

@@UpsideDownFork thanks for the addition figures, hopefully this year is going to see a lot of EVs in the £25,000 range with a 40-50 kw/h battery (new renault 5 looks fab) if VTG becomes commonplace the your dual battery configuration plus the EV would provide for the electricity needed on even the coldest days and some headroom to spare. Thanks again for all the effort your putting in which is really helping others evaluations and decision making 👍

[@UpsideDownFork]

@@andyballard1883 Yes, personally if V2G becomes commercially available, then even smaller home batteries would be fine for most, say 5kWh that could keep the house ticking along if the car isn't parked on the drive. For us, V2G would be a gamechanger because our car isn't our primary means of transport and sits on the drive for 99% of the week anyway!

[@calysagora3615]

For the energy consumption aware, this is the consumption of a decent mansion with AC and Swimming pool.... Holy crap, someone is wasting power.

[@UpsideDownFork]

@@calysagora3615 Thanks for your helpful and judgmental tone. Last year's consumption was 2500kWh for a family of 5, I consider that relatively low. How much do you use annually? Since we have now cut off the gas, we are forecasting an additional 3000kWh in heating and cooking to be added to our existing 2500kWh, but we shall see by the end of 2024 if those predictions are accurate.

[@michals1108]

Not sure why no one see eon next offer . 8p between 0:00 - 07:00 so 7 hours of cheap rate and export is 16.5p flat from 7:00 to 0:00 . I’m using it for few months now no issues so far. Also octopus 7.5p only works with certain charges and ev when eon work with anything on the market.

[@UpsideDownFork]

That sounds good. Do you need any special equipment for that tariff?

[@UpsideDownFork]

I can't get a quote on their website because I don't have gas for a dual fuel tariff.

[@michals1108]

@@UpsideDownFork smart meter only at least in my postcode area which is Somerset , and I'm only using them for electricity, google EON NEXT DRIVE

[@magicker8052]

We were paying 300 quid a month on electric.. failed dismally to get usage down so needed to do something drastic. 18k on solar panels and batteries and that has been cut to less than 100 quid a month. So easily on track for an 8 year pay back WITHOUT exporting (long story). The gamble is of course access to smart tariffs.. if these go.. then all bets are off and we are screwed. Load shifting in winter has been amazing

[@pauld3327]

Don't forget opportunity cost

[@GWAYGWAY1]

If you have space ,what is wrong with lead acid battery bank, loads of leisure batteries are cheap no at 65pounds and will not burn the house down.

[@UpsideDownFork]

Could you please give me an idea of how much 10kWh of lead acid batteries would cost, including cables and BMS?

[@BestEDMSongs]

But can you put a price on a no power blackout ? With a battery, your house will be the only one on your street with the lights on when everyone else is in the dark and no heating and remember your solar also works in a blackout as well because of your battery. If you can afford it do it if you can't save up

[@UpsideDownFork]

Very true point.

[@angusgeorge8003]

Hi I have 6.5kwp panels and 16khw battery and 1 EV for 9 months and 1 for 6 months and we imported 3000kwh for 2023 on OG and IOG both had the cheap rate of 7.5p and we used 95-99 % on cheap rate. The average price per unit was 10p ish.

[@ecoterrorist1402]

nice

[@UpsideDownFork]

Thanks for the comment and congratulations on a good setup!

[@wgj4813]

In the uk my standard price is 26 p at the moment. A friend with a battery 10kw is managing dilligently on a half hour tarriff which is highly variable from pay to use!!!!! to 36p. By using the battery he has had monthly averages between 9 and 15p. If you dont have a battery you will have to use peak rates when you use most electricity and no doubt that average will be around 26p. Now you can see the saving. If you have solar in the summer 8 months grid provision can be down to as low as 1 kw a day. Now from those values you can calculate sort of your likely savings and see when you get a battery payback.

[@UpsideDownFork]

Thanks for the comment. See my latest video here for even more calculations about why a battery isn't for everyone kzbin.info/www/bejne/nommmo2tobmooZI

[@dstewart549]

My short story: I calculated that the Fogstar 15.5kWh battery wouldn't be big enough for my household use case (plus don't forget you shouldn't pull it lower than 20% DOD). I now have the Fogstar server rack style case + 4x 5.12kWh = 20.48kWh. Again running no lower than 20% DOD gives useable capacity 16.38kWh. Fogstar batteries are including VAT so your pricing is correct. My total cost of parts (batteries, hybrid inverter, cable, wifi link, trunking etc.) = £4948. I am charging up to 75% in the Summer and 95% in the Winter to allow space for the solar array (2kW) to pop a bit back in. I use Octopus cheap overnight charging which is now cheaper than your spreasheet and from 00:30 to 05:30. I don't intentionally export anything from solar, the battery charges up to 100% first followed by a solar diverter to the immersion heater and thermal store and last resort...... pop something on charge. I just ran some numbers and am saving £103 per month. Buyback estimated to be 4 years!!! My one concern would be longevety of the batteries and inverter, the batteries are rated to 4000 cycles (11 years) and the inverter 10 years. Fingers crossed at the time of failure or substantial degredation technology would have improved and prices reduced significantly. We'll see but for now I'm enjoying the journey. Ps I plan on adding a further 2kW of solar in the near future as the inverter can handle it and it's dirt cheap right now.

[@UpsideDownFork]

@@dstewart549 thanks for commenting 👍

[@beebop9808]

That battery pack you're looking at is probably the best price I've seen on a turn key pack, wall mount or server rack. Some of these companies providing them are beginning to pick up on the larger cells and not so much lowering prices but bumping capacity. Same difference but whatever works. That price can still be beaten but you'll have to do it yourself. Certainly not for everyone but I've got $10k invested in six battery packs providing 90kwh using 304ah EVE cells. I do agree that more is always better when it comes to batteries. Four or five days reserve is always good for bad weather. Also providing lower depth of discharge and allowing lower C rates both in and out. All of which is extending the life of the cells. Always better on the equipment to cruise down the highway than scream around the racetrack all the time.

[@UpsideDownFork]

Thanks for the advice 👍

[@stephenmanning1553]

I totally agree with you. I moved from London to the desert of Western Australia, (London 0C today, Cue 45C today so pretty similar climates). Ruth and I have our second 5KW solar system operating. The old one served us very well but after 10+ years finally died, not owing us a cent, did really well. Meekatharra which is 125 KM to the North of us is supposedly the sunniest place in Australia. A German company tested out a very early solar system there some 35 years ago with success!! With cyclones, violent storms and shocking heatwaves oh and bush fires disrupting mains supply we have considered batteries and have come to the same conclusion as you. I would still like to investigate the Nickel/Iron batteries that were used in London milk floats. Lots of batteries still in use in the 1980s were manufactured in the 1930s. They are VERY heavy but I don't see this as an issue. Once installed they can sit where they like. Yes,. their energy density is far less and probably less efficient but they will outlive me

[@edc1569]

Hard to beat LFP in terms of value and lifetime

[@UpsideDownFork]

Thanks for the comment! Very interesting. Keep enjoying down under, my brother in law now lives in Perth!

[@seatonian]

A lot of great content in the video and, equally, some good points already in the comments. There are many intangibles and 'what ifs' already raised and, although I appreciate it only serves to muddy the waters further, here's another one :) - (some) dependency away from the grid. There are any number of reports that predict increasing power outages. Admittedly, some of them are probably self-serving by promoters (both direct and indirect) of alternative energy solutions but losing power is at best an inconvenience but can also be much more serious and costly. By having your own in-house electricity store, you can help mitigate the impact of power outages. What that is worth to you - or anyone else - is very much an individual thing and probably quite difficult to put a £ value on. (You may also need to factor in costs to provide 'protected' circuits. I did say it would complicate things further!! :) )

[@UpsideDownFork]

Thanks for the great comment! Energy independence is definitely something we are aiming for, as and when funds allow!

[@alanclark2584]

I've just added another 3 pylontech US 5000 batteries which is really easy to do. I paid below £900 each. As we agree price point is all important and VAT should not be added from wholesale battery prices but they do put it on. However some suppliers now willing to sub contract you as the installer for a small fee to make it legal and you dont pay VAT. Prices already dropping but this makes it worthwhile in my book.

[@UpsideDownFork]

That's a good price you got there.

[@SimonTheDIYer]

Payback time is usually the same as solar 5-7 yrs usually giving you a decent ROI. Only caveat risk is cheap rate could be cancelled anytime/year. Like others mentioned too 15.1kw your daily avg. so a single 15kw bat makes sense meaning your purchase price is let’s say 9p per kw then solar productions tops up from your am use would also mean avg you would not pay the full charge over night; then you’d export at 15p any excess thus making money. I installed a boiler heat element so it heats my 250ltr hot water before exporting thus reducing gas too as well as charging batteries. If you wanted to be really savvy double the batteries and sell your excess during the 4-7pm they pay typically 45p kw selling them their own electricity. If BES doesn’t make sense then why are BES farms popping so much we have one near us wanting planning for 500 container sized battery storage units! The key is not so much about making you money but ask what would you have spent if you didn’t have it! Which is very hard to calculate exact other than it will work for you! It can not work…

[@UpsideDownFork]

Thanks for the great comment!

[@MrKlawUK]

deffo look at the 8.2 givenergy upwards if you’re lookin gat them. Assuming you use a givenergy inverter you don’t get wattage output benefits running two in parallel I don’t think? But importantly for calculations they have a limited DoD (80% for the 5.2 I think) vs 100% for the 8.2/9.5. so the 5.2 is actually a 4.x kwh available

[@TheAdamRBell]

Thanks to a miscommunication, I ordered an 8.2 but ended up with 2 x 5.2 so I know all about the DOD confusion. The 8.2 is actually 10.25 so its 80% DoD based on the actual capacity but the spec sheet says 8.2 so you're getting "100%". The 5.2 is actually 5.2 so using the above logic it should be listed as 4.16 on the spec sheet....but it isn't 🙈 The biggest difference between the 8.2 and the smaller batteries is the 8.2 warranty has no limit on the number of cycles.

[@UpsideDownFork]

Thanks, i'll be digging into battery specs very soon!

[@davesoton20]

Avoid Givenergy if you looking at 5kw hybrids,, read the specs very carefully as their Hybrids are not great performance. They are only good for Octopus tariff integration. A Solis, Solax and especially Sunsynk inverter will actually do their rated outputs all day even on just battery, unlike Givenergy.

[@UpsideDownFork]

@@davesoton20 Thanks for the comment. Sunsynk is my number 1 choice.

[@stuartburns8657]

​@@davesoton20I ended up with GE hybrid 5k inverter and 8.2 battery. Think as I've now learnt more, I'd gave gone with Sunsync yes. The few times I've done a forced discharge for one of the energy saving events, the on paper 2600w output only achieved just over 2000w. 600w's just lost. We where on holiday, so beyond a few led lights and background applications, it was our typical 230w baseload

[@williamlabarre4755]

Excellent analysis. While we on the other side of the pond have different supply and rate structures, most are similar, so your approach to this work is quite useful. However, one dimension to consider when looking at storage is energy security. Depending on the quality of your source and/or the perhaps seasonal or storm effects, storage can be cheap at any price. But then you have to consider storage capacity vs. demand to compare to possible long-term (as defined by the analyst) needs.

[@UpsideDownFork]

Great point! Unfortunately most of the solar sales cowboys don't mention any of this. They never talk about energy security. They just appear to be on the upsell train to fit more batteries in homes that don't necessarily need them. In my part of the UK we do not get power cuts...yet. Thanks for commenting from the land of the free!

[@geoffreygriffiths4725]

The issue is what is the likely long-term price of solar. Many thoughtful people think that power prices will become more volatile but generally lower in off peak periods. The battery option only becomes viable if you can spread your load to avoid peak hour periods. Investing in new kit has to be partly an act of faith. If you've got the cash and you think it will cut costs it's probably worth it. Your pay back calculation is good but doesn't make an allowance for inflation or power prices becoming more volatile. Grat video very informative.

[@UpsideDownFork]

All very true. I have delved into some of those points in other videos on my channel 👍

[@geoffreycoan]

Agree you need to do calculations like this. My own spreadsheet on adding a 3rd battery gives a payback of 5-22 years depending on different assumptions! Your spreadsheet didn’t seem to cover the scenario of self consumption of the solar and storing self generation to use later - this is the best use of a battery but of course predominately summer. Few things to highlight: - multiple GivEnergy batteries don’t increase charge/discharge rate, the inverter sees them as a single large battery🙁 - look at depth of discharge. The GivEnergy 5.2 is 80% so only 4.2 usable 😣 - likely you’ll need the cost of an inverter to make use of these batteries unless you get a hybrid - for Octopus Go you do need an EV (or one on order) - Tracker rates are not guaranteed, they can go up substantially, and if leave Tracker you can’t go back for 9 months. Part of the reason I didn’t go onto Tracker for the winter

[@edc1569]

Always tempting to oversize battery systems but it’s a terrible idea, agree that you should just use the grid occasionally,

[@UpsideDownFork]

Brilliant comment, thanks! The assumptions are definitely the flawed part of my calculations. That's why the comments section is very helpful to correct some of the assumptions i've made. I'll update and bring a second video to account for your input and that of other commenters.

[@UpsideDownFork]

@@edc1569 Thanks for the comment. We've used 45kWh per day in the recent cold snap but in the summer we tend to use under 10kWh per day. Our usage profile will be a very pronounced V shape compared to most which makes home batteries even more challenging!

[@paulf3353]

I actually concluded exactly opposite considering our annual usage of ~8000kWh per year. We were on Go tarrive, no solar, just batteries, and averaging around 8p per kW for last few years. It is savings around 2400GBP for last 2 years, I bought battery for 2k, so it is already paid for itself. There are still inverter cost + installation ( which i did myself), but that's under 1k. Considering I've switched to tomato energy with 5p per kWh, return of investment will be just 3y in total for us.

[@UpsideDownFork]

Every use case is different. Averaging 8p is good going so it's clearly working for you. If you had been on a tracker tariff without a battery, the average rate over 2 years has been 17p, so at 9p difference, you would have saved £1440 by using 16,000kWh over those 2 years. Of course compared to the price cap tariffs, your savings would be higher. More recently i've had a couple of months where I have averaged below 12p import without any batteries. Thanks for contributing to the discussion.

[@Simon_Rafferty]

As other people have commented, most of us based our calculations on paying the £0.30+ per kwh. Now there are much better deals available - so it makes less sense. Our solar + battery installation cost £13k and in the last 12 months has saved £2k compared to what we were paying in the year Feb 22 to Feb 23 - so a payback of 6.5 years. With the current best prices, that increases to over 10 years. However, it does give us security from whatever happens in the future! We also have it set up so the house switches over to battery in the event of a power failure - which are surprisingly frequent here. I like being the only house for miles around with the lights still on!

[@UpsideDownFork]

All good and important points. The market continues to fluctuate and we can only get a relatively clear picture of what the energy market will do in the next 3-6 months but beyond that is crystal ball gazing. If you have the means, then shielding yourself against the future is always wise.

[@christopheredmondson1338]

Thank you for a very good video, I'm in total agreement, all the quotes I received included batteries, £4000 for two 5.2Kw batteries with the Octopus quote, I couldn't see how the figures would add up with my annual electricity consumption of 3500Kw, I have no plans for an electric car, or moving away from gas central heating and hot water, although we may choose to change our cooker from gas to electricity in the future, we are both retired, so are mainly at home during the day. Battery storage may be a good option for people not at home during the day. My planned 6.12Kw system has an estimated payback of 7 years and 6 months, the payback would be at least double if I had included batteries which is about the length of the battery's lifespan. It seems that the cost of batteries will continue to reduce and no doubt the performance will improve, I will keep an eye on battery storage for the future, but at this time, it's not for me.

[@UpsideDownFork]

@@christopheredmondson1338 well done for doing your sums and not just blindly listening to the sales people.

[@hyweljthomas]

I have a 9.5 Givenergy battery and no solar or EV and, with a switch to Agile, save around £100 a month - a 4 year payback. Our previous cost per kWh on Flexible was 27p, in the past 4 months it has dropped to around 11p. This may creep up with higher Agile prices and lower summer use, but I would be very surprised if payback was more than 5 years.

[@Adventures-with-Ty]

Great video and breakdown, thanks! It all depends on your use case scenario and where you see your energy usage heading (eg are you planning on getting an EV in future etc)? The main reason for getting a battery will be energy security (eliminate reliance from the grid completely) and the ability to export your unused solar back to the grid at peak times. Battery and Solar are not binary propositions (ie not one or the other) I would say design and build your system in a way that takes advantage of the solar now, with the ability to scale and include a battery later. I'm currently researching into how to add a used EV battery to a solar set up (90kwh secondhand for £2000) there's tons of videos out there if folks repurposing used EV batteries into their solar set ups. That's if you really wanna go green!! Cheers

[@UpsideDownFork]

Very much agree.

[@andrewosman982]

How long does it take to charge a 5kw battery and can it charge up at the same time as my car?

[@UpsideDownFork]

That depends on your inverter and your DNO. Some will charge it from flat to full in an hour and most DNO will allow both car and battery to be charged simultaneously.

[@trailblazer7108]

Can you advise which battery you’re thinking of getting? I’m thinking about the Tesla 3 because of the discharge rate, but I’m sure you’d have a far smarter choice.

[@UpsideDownFork]

Fogstar is in the lead for me because it works well with my SunSynk inverter. Tesla PW3 is a great option. If I had to start again I would seriously consider it.

[@Sean_S1000]

The inverter you are having installed will have different charge and discharge rates for batteries compared to its rated output, they usually max out around 3kw so it wont be able to run a heat pump and house load without additional solar or grid load which is something to consider

[@UpsideDownFork]

Thanks for the comment. We're now heading towards the SunSynk 8kW which has a beefy charge and discharge rate for any battery system we decide on in the future.

[@Sean_S1000]

@@UpsideDownFork ironically I am looking at that to, but I am still thinking about if I am going to get solar or not. But I have been following fogstar for quite a while and was tempted by their new battery offering even to use it without solar panels. I thought the pay back period with inverter was quite reasonable

[@UpsideDownFork]

@@Sean_S1000 Ok, watch the channel for much more sunsynk 8kw content coming soon 😉

[@marinostsalis314]

Off the shelf battery system are a big cost on the other hand DIY ones are almost 1/3 of the cost so if you have a big consumption its a great solution.

[@UpsideDownFork]

Yes, DIY does seem to make some great sense for those with the capability to do it and it appears that many of the DIY systems are not as compact as the retail commercially available packs.

[@marinostsalis314]

@@UpsideDownFork actually most DIY that looks big are 3 times bigger in every aspect as they are 3 times bigger in energy storage. Most DIY batteries you will see on KZbin are 14kwh battery packs at a cost of a 5kwh of the commercial available battery that's why they look so big there is no reason to go for a small diy system unless you have space constraint or small system. If you open up 95% of commercial batteries you will find the same parts as the diy ones, batteries are batteries can't change much on how you make them.

[@UpsideDownFork]

@@marinostsalis314 That makes complete sense. Are there wall mounted cases for DIY battery systems?

[@marinostsalis314]

@@UpsideDownFork yes there are, also you can go with heavy duty shelf if you are in a budget. The only problem with wall mounted systems is you can't go with big batteries if you don't have a solid brick or concrete wall due to their large weight that's why most commercial ones are 5-10 kwh batteries and the big ones are always placed on the floor for safety reasons and ease of installation and maintainance.

[@bermudatriangle2036]

@@UpsideDownFork All these batteries are made from lithium ion phosphate cells made in china and sold on alibaba for about £80 per kwh. people are just putting them in a case, connecting them up and selling them for 3X more. I think its only worthwhile to buy and connect the cells yourself but I don't know if you would be allowed to connect that to the grid.

[@richardkeith2778]

Hi, we are a few months down the road - any change of thinking on this now?. I came to the same conclusion with simpler math - a £3650 battery over 10 years would add an additional service charge of £1 per day, which would need to be recovered through export or time-of-use shenanegins - not worth the candle for me !

[@UpsideDownFork]

@@richardkeith2778 yes, your maths is nice and simple! The gap between peak and off peak pricing has narrowed a bit since I made this video so if anything, the purely financial case for a battery has moved further away.

[@JohnMulkerrin-p2w]

Great video. One way to improve this is to buy 2nd hand ev battery to use instead of purchasing new, dramatically improving ROI. You are right though, if youre not careful in pricing the equipment it can make it relatively more expensive. But there is an environmental return to take into account, although this isnt priced as such its the most valuable return on investment.

[@UpsideDownFork]

Great strategy for those who have the physical space and the technical ability!

[@daveoram7249]

The FogStar battery was rated for 3300 cycles. Assuming a Discharge every day it will last less than 10 years. Is there a Warranty of greater than that? If payback takes 10 years then that battery will have died before then and in the intervening years will gradually deteriorate so will not manage the full storage capability

[@UpsideDownFork]

Thanks for the comment. Some batteries are indeed rated for 6000-10000 cycles but it appears that in practise, real world installations are typically performing better than this!

[@grahameconnolly807]

@UpsideDownFork I am looking to have a 7.5kW array fitted in the next month or so. I have considered batteries but reached the conclusion that the cost would exceed the gain. During the summer months we will export considerably more than we use and in the winter would expect to import considerably more than we generate. The net difference after exporting 3095 kW @15p and importing 2112 kW @ 22p is 39 pence (yes really!). This is all based on solar generation of 7875 kW and total requirement of 6892 kw (self generated and imported). So without batteries the total energy purchase cost per year would be really just the standing charge. I ran another spreadsheet to include a Tesla battery and maxing out charge/discharge on Octopus Intelligent Go EV tariff produced a saving of just less that £200/year........ I can live without back up so I'd rather keep the £8000 or so that the Tesla will cost to fit! I should add that we will have a heat pump for heating and these figures are based on that (much higher need for kW's),

[@UpsideDownFork]

Well done Graham. It sounds like you've done the exact sums I did and came to the same conclusion. If you look at my latest solar stats videos you will see that I am doing exceptionally well with this strategy and have coined the term seasonal offsetting to describe it. Currently on the agile tariff and my import rate last month averaged below 15p. Good luck!

[@1KentKent]

I ordered a similar DIY battery box, batteries, cables, BMS, balancer from China and put it together myself. All in...US$2500. My solar charges the battery daily, and my daily battery usage is 14kwh. My savings calculation is: 14 cents per kwh x 14 kwh daily use x 365 days in a year x 4 years = $2861. This calculation is a little optimistic but I should break even in 4-5 years.

[@UpsideDownFork]

@@1KentKent nice work! 👍

[@pmac6584]

I would caution being first when a new product lands. I have HanchuESS batteries and a Lux inverter, they work perfectly now but it took a month to sort out as I was the second person in the uk to get them. Happy with them since though and lux were fantastic.

[@UpsideDownFork]

Thanks for the warning! I'm in no rush to jump on the newest battery!

[@andypag1071]

Cost per kilowatt is a secondary criteria. First calculate the battery size needed to get you through the day - worst case X frequency of worst case + best case X frequency of best case + everything in between), then find the cheapest deal for that size battery.

[@UpsideDownFork]

@@andypag1071 but if like me you need a minimum of 15-20kWh then cost per kWh does become critical at that size.

[@marklefler4007]

Good analysis. Looking at say a Powerwall 3, which should last about 5000 cycles taking into account expected degredation, adding in install cost, it will cost about $0.19 USD per kWh shifted. Unless the difference between peak and off peak rates is at least that high, or you do not have net metering, it does not look cost effective for us. That is giving no credit to backup, of course. I say wait for the costs to drop.

[@UpsideDownFork]

@@marklefler4007 agreed 👍

[@rtfazeberdee3519]

Are you considering any increase in property value and change on electricity to rates over the next 10 years?

[@UpsideDownFork]

Thanks for the comment. I was trying to keep the spreadsheet simple so I omitted those things this time but may include them next time.

[@gsdevme]

As some of the comments have said, Batteries are not actually VAT exempt its only "installs" which is a shame.

[@UpsideDownFork]

Yes, I agree but i've just seen a quote that was previously £3600 inc. VAT reduced down to £3000 with zero VAT if installed after Feb 1st! If I was to purchase the battery myself it would only be marginally cheaper than having it installed by a qualified and VAT registered electrician.

[@YodhrinsForge]

Did the Octopus Flux tariff not exist when this video was made? Because odds are most of the people advocating big battery installs are on that one, and the reason it makes sense is a large battery enables you to engage in arbitrage, for example based on the modelling I've had done the house I'll be renovating to a high standard of energy/thermal efficiency soon will have a maximum typical daily consumption of around 7-8kwh, so assuming I bought two of those Fogstar batteries for a 31kwh total capacity and using the Flux numbers for my region, the total cost to charge the battery to full every day during the early morning off-peak plus the standing charge would be £4.64 per day, while selling the unused ~23kwh back to the grid during the evening peak period would bring in £5.06. Let's say the battery lasts ten years without excessive degredation, that little daily excess would amount to just over ~£1.5k which should cover the install cost of the battery so call it £500 a year. That beats Standard in your calcs by a factor of three, and Track by almost double. It's a little above Go but remember that's a *no solar* install, just battery. With the 14.6p day rate Flux gives my area for export outside of peak times and given how cheap solar panels are these days, if the grid operator lets me put a decent size array on the property that should pay itself off fairly quickly and then anything produced by the solar is gravy that further offsets the battery cost.

[@UpsideDownFork]

Yes, I have also considered flux. You should watch some of the videos on the Tim&Kat's green walk channel. He's done some more thorough analysis on flux and it's best use case.

[@xiaowei1]

Batteries always play best when night time electricity rates are high. We have time of use on my electricity plan in Australia. over 50c per kw from 4pm to 9pm. but during the day from 11am to 2pm it is free because of all the roof top solar we have. my battery cost (after rebates) $ 7,000 (au), which fills during the free time (when I charge the car, wash the cloths, run the pool pump, etc...). My 13.6wk batter the covers all my night time usage. for us, the math works out. we have solar to cover the other times of the day too. our bill was well over $1000 a quarter, and is now almost $0. So it works for us, but that is because we battled high energy cost, particularly in the evening. our battery saves about $5 to $6 each day, which means it will pay for itself in 4 or so years. I expect prices to continue to go up, which means it may save us even more moving forwards. it's all about the cost, and what it is off setting. as a bonus we are immune to blackouts with our system, unless it's around 3am when our battery depletes.

[@UpsideDownFork]

@@xiaowei1 thanks for sharing your perspective all the way from down under! Sounds like you've got a brilliant system working well for you 👍

[@bradleyarcher9840]

Hello, I never saw your original video but I think by watching this you’re going to be doing it wrong, at least from a financial point of view. Octopus intelligent go - 7.5p kWh off peak import, 31p kWh peak import and 15p kWh export. Charge a battery everyday, ideally aim for a size which is bigger than what you need, trying to use most things overnight. You basically live off the battery at 7.5p kWh, you set the battery to export mode meaning that any solar goes directly into the grid at 15p kWh, and at the end of the day if you haven’t used all your battery then you dump that on the grid at a profit of 7.5p kWh, repeating the cycle come 23:30. As long as you export at least half what you’ve used then you have cleared your electric bill minus your standing charge.

[@UpsideDownFork]

Unfortunately you need special equipment to qualify for intelligent go. 30kWh of battery storage just isn't feasible for most people. They will never see a ROI. More details here : kzbin.info/www/bejne/nommmo2tobmooZIsi=fLfV_2MhL51WiA4A

[@bradleyarcher9840]

Who on earth needs 30kWh? Most houses would need between 5 and 10kWh, givenergy batteries are compatible, as well as ohme car chargers, wallbox car chargers and my energi car chargers. A lot of EV cars are also compatible. I wouldn’t class any of that special, and with battery VAT at 0% I’m currently upgrading my battery from 5kWh to 15kWh (+10kWh) at £4,000. Future planning ready for a heat pump, but I can also fill and discharge it to help payback until I need the full capacity in winter for a heat pump.

[@UpsideDownFork]

​@@bradleyarcher9840check out some of my heat pump performance videos. Have had plenty of days of 40+kWh and one at 55kWh. The rest of our home use is very minimal, 5-10kWh per day typically. Trying to average out across seasons, we will need at least 20kWh batteries to make the strategy work in terms of cost parity and still not see a decent ROI once the capital cost is factored in. The reality is that a heat pump drastically changing your energy consumption profile over the year and makes batteries a lot less viable. Plenty of people in the heat pump groups using over 100kWh per day in their large homes when it gets cold outside. On the equipment issue to qualify for IOG, as previously stated, this is not a model I'm recommending for those with EVs as it can change the dynamic dramatically. Many of the GivEnergy batteries/inverters have very weak charge and discharge rates so whilst there may not be a struggle with 5-10kWh charging during the cheap window, a larger battery bank can become problematic. Also the slow ramping up of GivEnergy inverters leads to more grid consumption than necessary, even when the batteries have sufficient reserves.

[@Electronzap]

If you live somewhere that charges a lot for their power but wont pay much for your power, then a battery is more promising than somewhere that will pay you about as much as you pay them.

[@UpsideDownFork]

True. In my most recent video I show that I've been paying 14p for import and 15p for export. No brainer to avoid a battery at those rates. But we'll see how next winter goes.

[@jameshotten]

Surely the whole point of having a battery is using it in conjunction with a solar array? So your "true" payback on a battery is effectively how much you are able to use it once its been charged for free via solar. So for example, your evening/night electric usage becomes part of the payback. A bigger battery obviously allows more storage, but generally also allows it to feed back into your house at a greater kWh rate. When I've looked, this would mean that a decent sized battery would take care of almost all my electrical needs at night, and solar would take care of it during the day, while also charging the battery and a heatpump. Excess would earn a few pennies, and if needed the battery can be topped up at night using a cheap tariff. I'd then save almost all of my gas and electric bills, which are currently £2.5k a year approx.

[@UpsideDownFork]

You save more by charging at cheap rate i.e. 7.5p and then exporting your solar at 15p. Either way you slice itz the sun's are looking worse and worse for battery storage in a lot of cases.

[@chrisblunt7627]

Interesting analysis. I had a solar and battery (5.8kWh Solax) installed at the end of July, my household consumption is about 10kWh per day. Until mid September we were almost entirely net neutral of the grid, towards the end of September and into the winter months we have been charging up and running house load overnight, and on very poor solar days having to boost the battery in the afternoon. My tariff is Agile and my average cost per kWh has been between 8p and 15p. Long way of saying at 15p per kWh the £2k for an extra battery simply isn't worth it. At 15p per kWh that's 13,000 hours of electricity! Even if I was using the extra 5kWh every day that would take about 7 years to cover the cost of the battery. Of course the reality is the cost per kWh is actually the saving cost between a different tariff that you would be using without it. So, if I could use Go my cost per kWh would be 9.5p, meaning I would spend 95p per day for 10 kWh vs £1.50 therefore 65p per day saved - £2k at 65p per day = 3,076 days. Sure more extreme consumers would benefit from batteries, and I would say they are a game changer with solar as for a good portion of the year I can be self sufficient.

[@UpsideDownFork]

Thanks for the comment and sharing your real world experience! Agile and Tracker are very closely linked when considering these calculations. If you are very proactive or have an inverter/battery that can connect to the Agile API then there is a lot of potential to make good savings, especially through forced export at peak periods.

[@laurencedamazer2260]

Totally agee, £3k battery saving me about £200 to £300 p.a. Not sure when it blows up if even if will replace it at current tariff rates.

[@BassPunk]

Great things are usually expensive and worth saving up for. My battery is always creating ~100w of heat so warms house and gives flexibility on when I want to use grid. Also allows for more solar capture if limited by inverter e.g. I force discharge my Solaredge battery while sun is peaking so battery charges at the same time as its discharging. This bypasses the inverter limit, so 5.35kW can be captured rather than the regular 5.00kW I often seen plateaued in graphs 😎

[@nortonansell]

Was my impression that you can export at 15p and still be on inteligent oct go at 7.5 p for 6 hours ? This is what EV puzzle does with his setup ?

[@UpsideDownFork]

Yes to intelligent go. No to regular go. 👍

[@scottwills4698]

I charge my Powerwall at 7.5p per kwh and it lasts me all day. I then sell all my solar for 15p per kwh. Powerwall 2 is now £5k for the battery and £800 for the gateway if you want it. The software is the best part and it works out what it needs to do by itself - so if I use alot of electricity in the morning and it thinks I wont have enough electricity to get through to the next cheap period it will put some solar in to the battery to avoid peak draw, The battery quatered my peak energy draw saving me £1200 per annum so I will get my money back in 8 years (inc fitting) (im on Octopus inteligent). I draw 1 to 2kwh per month at peak rate and 880 kwh at off peak. I would say now the vat is off the battery it is more important than solar for cost savings.

[@UpsideDownFork]

Thanks for the comment. I've responded in this video: kzbin.info/www/bejne/nYebXn-Jm7N8h8k

[@rajus0]

Hey, another great video a few points. 1. Don't forget from Feb 1st VAT is coming off home batteries in the UK. 2. Not sure if Fog star includes an inverter, also not sure if I missed it but not sure if it states peak out and how long it can sustain that. 3. In your video if you had solar to, you would get free electric during the summer, where you can run your house almost totally from solar and batteries.

[@ecoterrorist1402]

1. Don't forget from Feb 1st VAT is coming off home batteries in the UK. this only applies to installation from a electrician that is VAT reg, (zero rate is subject to a class of VAT)

[@UpsideDownFork]

Thanks for the comment!

[@bertiesworld]

@@ecoterrorist1402 I was under the impression that if you ADD batteries at a later date, you currently pay VAT. My understanding is from 1st February VAT will no longer be added to the bill.

[@ecoterrorist1402]

@@bertiesworld that's correct, thou VAT at zero only applies to domestic UK and only with a VAT Sparkie, VAT on goods are claimed back from the trade's man from HMRC every 1/4.

[@Th3_Gael]

It's about time VAT was gone from everything

[@dancingfrogsxb1276]

I worked out you can save £350 ish per year charging over night and using it in the day, and hope to sell back in the summer at the peak rate a few KW each day, I'm not sure if it's really worth it but with the rate at which electricity is going up and the growing wealth divide it's seems better to plan for future security now.

[@UpsideDownFork]

Thanks for sharing.

[@dk8435]

Don’t know how you got on with this but even in winter we’re running primarily from battery for well over 90% usage, very close to 100% house only spills over on to grid if we need high loads for very short periods, I.e. 2 ovens/oven + kettle but even that would be better with a newer higher power inverter, ours is limited to 3.5kw output.

[@UpsideDownFork]

Thanks for replying. Do you have a heat pump?

[@mikejoseph425]

I am not understanding how you arrive at your savings. Assuming you have dual tariff with Intelligent Octopus Go and you use 5500kWh p.a, Without off peak @ 31p = £1,705 Even though in practical terms your 5500kWh won’t be divided equally by 365 days, to do your calculation of how much battery capacity you need will make that assumption = 15kWh day. So without Solar you will need 15kWh battery plus at least 10% so not to run your batteries to zero if you want to avoid On peak charges during the winter Off peak @ 7.5p x 5500kWh = £390 so your uncomplicated saving is around £1300 p.a. It starts to get more involved when you introduce Solar as in the summer you will have a potential large over capacity, but if you are paying 7.5p or zero and exporting it back at 15p it increases your savings so no problem there If you have Solar don’t forget the bird mesh and if you want your battery to supply the house during a power cut you need essential and non essential consumer units and arrangements to “Island” your house so not to electrocute anyone working on the grid Finally in my view, rate of return as in how many years is irrelevant as if you sell the property you are likely to get some extra on the house but more importantly assuming you don’t have to borrow the money look at the tax free savings each year v how much you get from any current investments which except an ISA will be taxed

[@UpsideDownFork]

Thanks for your comment. Intelligent tariffs are currently restricted to a very small number of products so I chose to omit them for this comparison. My base cost is the tracker tariff, not the price cap tariff, which makes a huge difference. The opportunity cost of investment elsewhere is an interesting factor. I may include that in a future video.

[@terry2346]

I am having trouble being able to justify the cost vs the ROI for our household which uses ~500KWh per month. Also do the people calculating this take into account the cost vs what could be gained in valuation of a 5% CD or savings rate over the 5-10 year period? Our electric bills have been averaging about $85 a month and for that amt I just can'[t see getting a solar with battery, etc. Also I am 72 and payback/breakeven time is far from certain! :)

[@UpsideDownFork]

Thanks for the comment. You'll probably find this video helpful in which I discuss the opportunity cost etc. kzbin.info/www/bejne/nommmo2tobmooZI

[@MikeGleesonazelectrics]

Sunsynk seem good, i have 2 different family members with these and also have attended their technical sessions but i havent installed any personally. They are very compact and can be added to. But givenrrgy do larger batteries, and also All in ones (has integrated inverter).

[@UpsideDownFork]

Thanks for the comment. Just wish they offered 10kWh batteries so I could buy 2 of them instead of 4 x 5kWh!

[@MikeGleesonazelectrics]

@@UpsideDownFork but it does give you the option to build up the capacity ad and when you need it. As I say, its winter is the testing time but as you'll be on a SEG (I'm not) then summer export income will also be significant.

[@UpsideDownFork]

@scrapyardwars Sunsynk you mean? My installer seems to regard sunsynk's support as very good.

[@alsmith20000]

One thing I've seen with prices of items that are not actually available yet is they promise low prices to get you invested emotionally and then the price goes up when they actually have it. The battery also has the issue of little reputation or reviews. Perhaps it will not work very well.

[@UpsideDownFork]

Thanks for the comment. A good point. I'll be sure to do my due diligence.

[@AnthonyJoyce-x2t]

Look at number of charge cycles (life cycles) this is the total number of charge/ discharge the battery is predicted to work for. Most warranties will state number of years or cycles

[@UpsideDownFork]

Although that's the case for warranty, most batteries will still perform well, 2 or 3 times longer than their stated charge cycle guarantee. It is something good to look for though, the difference being between 3000 and 10000 cycles on the various ones I looked at. Some even specifying a percentage, like after 3000 cycles you'll have at least 80% usable capacity still available. 👍

[@paulkinnaird1930]

Trying to work out the payback on batteries is going to depend so much on the current cost of electricity. When it is high at say 40p/kWh saving is a big feature. As the cost are now falling to 23p/kWh the payback years extend out well beyond the life of the batteries. But I have solar with batteries and an EV. The demand on the home now is 3500kWh/pa but before it was 7000. Reducing demand is a benefit to me as well as to the National Grid.

[@UpsideDownFork]

Thanks for the comment. I've responded in this video: kzbin.info/www/bejne/nYebXn-Jm7N8h8k

[@EverydayLife621]

Possibly in 2024, but in 2022, it was a no brainer, we save £5/day using batteries on the house alone, and have almost paid for the system (and if you add the savings from having an EV, compared to derv.), we're probably over the line already. Ive had a quote for a heat pump of £7500 from octopus (plus i can get an extra £2k from my mortgage company), but oil is at 7p / Kwh, so cant see a heat pump making a financial sense in our case (spend around 1000 litres / year = £700) , as winter COP rates are 2-3 on a HP?

[@UpsideDownFork]

Thanks for the comment! Yes, the energy market has been a roller coaster since 2022 and you definitely would have made the most of that bad situation! With an EV, you'll probably still be better off using a home battery, especially if you are on intelligent go. My HP CoP so far is averaging just above 4. System commissioned mid November and if you haven't yet seen it, you can find my figures on this video. kzbin.info/www/bejne/l5-VZH-tobqbpZI For us, jumping from an old non condensing boiler to a HP with a CoP of 4, it will save us more money than anything else we do. Already £200 saved in 2 months. Because the old heating system was 27 years old anyway, we were faced with renewing everything anyway, so the HP after grant and VAT relief actually worked out cheaper in our case when looking at the capital costs. The lower running costs are just a bonus!

[@MrKlawUK]

try running two sets of math. One for baseload which will be relatively stable through the year. The second for HP which will be limited in months and very scalable (eg super high in Dec/Jan/Feb vs relatively low in shoulder months). without a battery I’d expect octopus go to not be huge value for HP. For baseline it may pull your average below tracker (for IO ours is about 11p/kwh) so thats worth doing, but HP will blow that back up again later so probably better on tracker during winter (but you can’t switch for 6 months after coming off tracker so timing critical). if you have solar then tracker+go works well for baseline. Push appliances overnight, decent size solar probably generates enough during spring-autumn to almost offset your peak baseline usage. Your saving will be a lot of CO2 due to your demand going down but costwise around 3p/unit vs 18p so a saving of 15p - not bad but solar install is also expensive. HP almost certainly again needing peak rate. honestly unless you live in a huge house with big roof, expect to pay tracker rate for most of your HP unless you want to reduce demand on grid and eventually break even. It might not save you a ton of money quickly but it’ll cover its costs and keep your grid demand low which may be an important factor for you (it was for me)

[@robinbennett5994]

That's a really good point, the needs of a heat pump could mean that you're better on Tracker, and out-weigh the needs on an EV that would be better on Go.

[@geoffreycoan]

I think it’s 9 months before you can go back onto Tracker. Agree with your points about a heat pump consumption, ours completely dominates our winter consumption and there’s no way I could have sufficient battery storage or cheap rate charging to meet the demand. For those reasons we went to Agile. The battery takes the peak off so our average import rate is about 18p

[@UpsideDownFork]

Thanks, so many good points in there that I agree with! My spreadsheet is full of several assumptions, the HP being a difficult one to currently forecast for but i'm hoping to have good data by April time!

[@andym1548]

Annual consumption and what solar deal you got makes a big difference. We are on the old FIT rates so get about 19p/kwh for generation whether we use it or not. Also get 50% deemed export. We use about 15,000Kw per annum with about 40Kw of that a day on the house and the rest into the EV. So if we put in 40Kw of battery and charge it at night on Inteligent Octopus at 7p/kw we can save at least 40 x 24p/day before factoring in Solar.... somewhere in the £3500 per annum.... I'm still challenging my own maths but I reckon we will be looking at 3-5 year payback depending on the quotes we get and the solar generation. Either way though for us definitley worth it but like EVs they are not for everyone ...Yet!

[@UpsideDownFork]

Thanks for the comment. FIT is definitely a different kettle of fish. This video and my calculations were mainly aimed at those who are looking to get solar and/or batteries in 2024 from a fresh slate. Everyone's situation will vary so important for each to do their own sums!

[@sohailm6]

You are mixing offers you can’t get 15p seg if you are on octopus tracker. You also use octopus tracker average but peaks can be £1 per kw which is prob from 6-8pm and your solar array won’t be doing much for 50% of the year. You need to do a best and worse case but your calcs are all best case

[@UpsideDownFork]

Thanks for the comment but you better check the octopus website. I think you are confusing agile and tracker. Tracker has a variable rate based on the wholesale.price but it gets fixed every day so it doesn't have a peak/off peak fluctuation. 15p fixed export is available with tracker.

[@SarahStuff-p5u]

Im in the USA so situation is quite a bit different overall, but in general from my experience....if you have solar panels, have at least enough battery storage to make it through the night comfortably. For me personally 10kwh of storage for my 2kw of panels has been plenty to get through the night.

[@UpsideDownFork]

Thanks for sharing a perspective from the other side of the pond!

[@DFowlesVWID7Tourer]

It is a different ball game though if you have your system installed inside and do not need an IP65 'outside' battery pack. For instance you can get Fox Mira HV25 batteries for £632 per 2.45kWh and are modulised but you need a BMS unit about £235 so for a comparable system for ~5 kwh would be £1499

[@ecoterrorist1402]

is that nett + vat price

[@UpsideDownFork]

Thanks very much. We would put the batteries in the garage but they must be wall mounted.

[@ecoterrorist1402]

@@UpsideDownFork Not all batteries, Advise Always Follow Manufacturers Instructions.

[@UpsideDownFork]

@@ecoterrorist1402 yes, I've discounted any that can't be wall mounted.

[@njipods]

One thing you're not considering is that you won't be drawing an average amount of power on the tracker. Like most people you're going to draw more power at peak times when it's more expensive

[@UpsideDownFork]

Broadly speaking, yes! Supply and demand will always dictate that. Since someone else mentioned this, I downloaded the tracker prices in csv format from the mysmartenergy.uk website. Coupling this with my energy consumption data for the last 3 months, the trend does exist. When I use more, the rates are higher. BUT, there are lots of outliers. 27th Jan is a recent example. Tracker rate was well below the average but we consumed well above average. I should download the grid mix data and overlay that to figure out the exact trend that produces so many outliers. Perhaps on some very cold days it is also very windy and lots of cheap turbine power available in the grid? Anyway, thanks for raising the point, it's an important one!

[@njipods]

​@@UpsideDownFork Thanks for the comprehensive response. IV got an EV so I will probably be on octopus go by default.

[@UpsideDownFork]

@@njipods If you can get a charger that works with intelligent go then you're definitely on to a winner!

[@njipods]

​@@UpsideDownForkIV got a Tesla so the car itself supports it. Although frankly it doesn't always work well. I will consider swapping to a charger that supports it.

[@UpsideDownFork]

@@njipods Might not work out financially viable, depending on how many miles you do. 10,000 miles per year will save £37.5 in charging. Octopus Go vs Intelligent Go. That doesn't account for any household consumption that you could also benefit on the lower rate. Also assuming you can average 4 miles/kWh.

[@racingrob108]

Very interesting comparison. I know it may be harder to include into your calculations, although losing out on export income, you would be filling your battery with electric you can use for free if it is included with a solar array.

[@UpsideDownFork]

Thanks for the comment. I think i'll try to include that in my next video!

[@jchidley]

I did similar analysis for batteries. I didn't think that it was worthwhile financially. My conclusion was that it's a hobby for some people. There's nothing wrong with that. I do lots of DIY and I kid myself that I'm saving money but mostly it's about my own entertainment. As for solar panels, my analysis showed it's best to install the minimum amount of panels as cheaply as possible (just under 4 kWp is great because you don't need DNO permission). I have some garages with south facing roofs that I could install panels on myself (there's a company called Plug in Solar that does kits). I will be installing an air source heat pump this year or next year. I don't expect to save money but I do expect to save CO2.

[@MrKlawUK]

I’d absolutely disagree with this. In your case if you’re DIY maybe. But most will need an installer and scaffolding. Those costs are hugely more than the cost of the panels. I would totally recommend filling every available space on your roof. If necessary if you can’t get DNO approval for larger export, you can sitll use that in the house and have a second inverter to restrict export. Or just oversize the array vs inverter so you get more of the max output during spring/autumn (and you squeeze what little there is in winter)

[@jameswestgate416]

In my experience with my solar installation you want to install as much solar you can fit on the roof. This is because the costs of install such as scaffolding etc are quite high and panel prices have really dropped. It’s actually fairly rare that the panels run at 100% efficiency and your inverter will clip 150% to 200% of your solar output vs inverter rating. With export rates now getting more attractive you want to get at least 5.5kwh or about 12 to 14 panels which is more than most can fit. You can also try get dno permission if you have a bigger roof which may be worth the payoff in the long run. Each install is different but this is my experience I thought I’d share here.

[@jchidley]

@@MrKlawUK If I was going to pay someone else to put panels on my main roof (requiring scaffolding), I'd max out the panels. It's going to be a long time before it pays back with those costs.

[@UpsideDownFork]

Thanks for the comment and interesting analysis!

[@UpsideDownFork]

​@@jameswestgate416 Thanks, that's my thinking too!

[@tomking5855]

Based upon the present cost per KWh for battery storage, a battery would only make sense if you use it to heat your home using electric heating. The savings on gas or oil would increase the ROI, especially when using cheap energy and solar energy for heating.

[@UpsideDownFork]

That could be a good strategy. The opportunity for seasonal offsetting could also be possible with gas mains heating. Export excess solar during summer and build up credit on the energy account to offset the winter cost. So many strategies to choose from!

[@tonyfeasby1437]

Bang on the money. While the gap between tracker average and go/Intel cheap rate is so low & interest rates as they are there seems to be little point going for a battery at the minute.

[@UpsideDownFork]

Thanks for the comment! That's my thinking but of course these things could change quickly!

[@davidleggett4072]

Hi I’m new to considering solar and battery and our current usage is 3300kw per year. I have offered a 4kw solar array with a 9.2kw givenergy battery from Octopus for £10.400. Do you think the 9.2 battery is overkill. We do run an EV as well.

[@UpsideDownFork]

It depends on your overall strategy. You could definitely live from your battery and if you are on intelligent go with the 7.5p rate then you could be winning overall. Because you have an EV, the battery is most likely a sensible move. Besides your needs, the price is very high from Octopus. Get a quote from a local reputable installer, you'll definitely knock £2-3k off that Octopus price.

[@davidleggett4072]

Thanks for the quick reply. I thought the price was a bit steep. I will certainly look for another quote.

[@UpsideDownFork]

@@davidleggett4072 There's a questionable outfit advertising on Facebook to install 4.3kWp of panels with a 10.4kWh battery all for £5995. Whilst I wouldn't recommend the race to the bottom, i'm sure a good local installer will be somewhere in the middle. The best quote I had from a top end local installer was £12,775. 10.4kWh battery and 9.46kWp panels on two different aspects, including optimisers, bird netting, G99, 8.8kW inverter and all the bells and whistles.

[@americansfortruthandjustic7504]

When I go camping, the tent I use will never bring in any revenue. However, the tent "pays" for itself the first time it keeps me dry during an overnight rain. Batteries are not necessarily the best financial investment, but they DO have a return on investment and the financial return is faster when the prices of electricity goes up. Your assumption that the price of electricity will be the same 10 years from now is flawed. "Financial sense" of the return on investment depends on future electricity rates, but practicality during grid power outages is priceless.

[@UpsideDownFork]

Good points, well made! We've seen since the making of this video that unit rates have tumbled and many forecasts are showing lower rates for the next couple of years before rising again. BUT, no one predicted the energy crisis of 2022, so who knows what's around the corner? A battery could be a great insurance policy. Then again, many battery prices have halved in 2 years. If you are in an area that suffers with power outages then a battery with the relevant switchover kit definitely seems like a great investment. Lots of variables and differing situations. It's good to be well informed when making considerably financial decisions. Thanks for commenting.

[@lynnfisher4396]

@@UpsideDownForkGood point and the likelihood is that over time electricity prices will fall as more and more renewable energy comes on stream. Perhaps more importantly the price of gas is used to set the benchmark for energy prices. There is now a concentrated campaign to break that link so that electricity is priced on cost to produce and not held artificially high by its linkage to gas. I have a Pw2 and only use IO’s 7p overnight rate, I am considering getting a further Pw2 while I can and will then basically reduce my electricity costs even more. It will certainly help when I eventually get found to fitting an ASP.

[@streaky81]

Battery doesn't help you if you can load shift or have an EV to charge, it helps you access cheap tariffs if you don't have an EV or can't load shift. I'm not sure if that's what that's what you're saying, but it sounds like it might be. The problem with batteries is like solar - it's not the kit itself that's expensive, it's getting it installed. For me I know without solar it'd help me massively reduce my costs because I have the data of not just total use but when and how I use energy, there are just reasons that aren't directly financial that I can't do it, yet. What you can't really do is use a battery to overnight charge at cheap and during the day sell back and make money doing it with excess - the spreads simply aren't being passed on to consumers, even with octopus, and that is a scandal when you listen to Ofgem, the industry and government and what they're claiming they want. One of the big things with both solar and batteries is they start to make more sense if we can git standing charges gone - it's a bit of a lifelong mission for me, because they're an even bigger scandal than the other thing, if they're gone and they get layered on peak tariffs (or just generally applied to a per-unit rate through the day), where they should be, it's going to make a huge difference to the viability of both. If you have solar OTOH they're a no-brainer no matter what, once they're installed as a no-brainer with solar, it becomes very convenient in the winter to 100% charge them at 3am or whatever. Also by the way if your batteries are sized appropriately (which you should have the data to do - and it isn't your total usage, it's what you expect to use out of off-peak times), there's no reason why you should be able to get well over 90% consumption on cheap tariffs through heating your water off-peak and using the battery for the rest. The complication a lil' bit is an induction cooker, used at peak, if it's rated over the capability of your inverter - and electric showers used at peak, but most shouldn't have a problem not doing that one; though it'll still help even if you do.

[@UpsideDownFork]

Thanks for the great comment! Apologies for not articulating myself properly. The video kind of spiralled somewhere that I wasn't prepared to go! One of the key messages I guess is that Octopus Tracker is currently a great tariff that can save many people a lot of money, even without battery or solar. Because of our recently installed heat pump, our energy usage profile is looking like a very pronounced V shape. 25kWh is fairly typical but last week in the cold snap we were over 45kWh per day. I guess i'll ignore the anomalies for the sake of battery capacity calculation.

[@tony5192]

@dougle03 is right! Try take a look a "basen green" kit. Is a diy solution but comes "flat pack" almost like an Ikea of battery diy.. way cheaper and still looks profrssional

[@UpsideDownFork]

Looks to be exactly like Fogstar.

[@stevenb7794]

If you use 5500kwh a year that's about 15 kwh a day so a single Fogstar battery is almost covering your usage. The solar would also top up a battery during the day and you wouldn't spend as much on import .

[@UpsideDownFork]

Thanks for the comment. I've responded in this video: kzbin.info/www/bejne/nYebXn-Jm7N8h8k

[@TheAdamRBell]

These spreadsheet videos are amazing. The fact you don't format 0.9 to 90%, love it!! 🤓 Keep up the good work. We have a battery and EV but no solar or heat pump (yet!) so we're the other half of the equation. As others have pointed out the average is good for a "back of the envelope" calculation but the operation and interaction of the various parts based on time of day, time of year, current or future pricing (both short term plunge prices, DFS, on/off peak and long term market trends etc) and grid CO2/kWh need to be considered. It would be difficult to build such a model without adding some custom functions to your sheet. My spreadsheet for the battery payback was fairly easy and the time has come down with newer products like Octopus Intelligent Go which give more hours of off-peak energy.

[@stewartburnett7303]

Same here, might get a heat pump in future, but that would require more storage, for 4 months of the year. Anyway at the moment we are getting >98% usage at cheap rate and saving ~£100 per month vs standard tariff. Payback about 5-6 years. The battery payback would almost certainly be longer with Solar, with the highest savings being in winter when there would be a greater need to import.

[@UpsideDownFork]

Haha! It's just me being lazy. The only formatting I usually do is minimising the decimal places! I'm ashamed to say that my sheet is full of assumptions, many of which are likely to be flawed in some way, so it's good to use the comments section as a sounding board and a reality check for me! Thanks for the great comment!

[@UpsideDownFork]

@@stewartburnett7303 Thanks for the comment. Although we typically use 20-25kWh of electricity since the heat pump was installed 2 months ago, in this cold snap we have had days of over 45kWh. For the sake of battery capacity calculation, we'll just have to ignore those anomalies and aim for around 20kWh of battery storage to try and balance our very V shaped seasonal usage profile.

[@paulmannion7097]

I’ve just done similar calculations and came to the same conclusion- it just takes too long to payback. A couple of observations. Have you looked at your daily consumption? Those batteries are quite small. I have similar peak consumption to you (5000kWh per year) and my daily average consumption is 10.5 kWh. Also that Fogstar battery is 48v and aimed at leisure usage I.e caravans, boats etc or am I missing something?

[@robinbennett5994]

48v seems to be standard for 'server rack' batteries, like Pylontech. Givenergy seems to be about the same too. How did you get 10.5? 5000/365 is 13.7

[@geoffreycoan]

Most home storage batteries are 48v. It’s the inverter that converts that to 240v AC, and as pointed out, that needs to be included in the comparison

[@kennyrodg]

48v is not aimed at caravans or motorhomes, all DC loads is industry standard at 12v, the vast majority of boats are 12v also. Household domestic batteries are 48v nominal.

[@paulmannion7097]

Re 48v thanks clarifying. Didn’t realise that. The 10.5 was the Mode Average as I had a few spikes from EV charging during peak times. My main point was that 4kWh usable battery wasn’t enough for me but getting a larger battery makes the payback too long for me.

[@SimonRGates]

There are two sorts of house battery, the most common are 48v (low voltage, 16 cells in series) which use an inverter to got to/from 230v AC. Some companies do use high voltage batteries (lots more cells in series), which should in theory end up cheaper as the inverter is simpler & more efficient, but for some reason are always more expensive.

[@grantmidd]

My opinion is like me get both. 7.2kwh array 455w x16 5kwh Givenergy Hybird inverter With 9.5kwh Givenergy battery. Production per year is just over 8Mwh. I use 6.5Mwh My tariff is Octopus Intelligent Flux 25.9p per kwh And 25.9p export tariff. Basically 1 for 1 from 19:00-16:00 With a 3 hour rate of 34.5p during peak time. I then export from the battery what I can spare. My £12k grid tied system will be paid back in 4-5 years due my export tariff. It's not even Government funded 🤣

[@UpsideDownFork]

Thanks for the comment! Have you compared against the tracker tariff or is this based against the price cap tariff?

[@grantmidd]

@@UpsideDownFork The paid back calculation is based on the price cap tariff with the price increasing due to inflation. What I'm actually getting out of my solar system is much higher than any of the prediction calculators. I have to make the inverter size the same as my solar system (7.2) to get the 8000+ kwh number a actually received last year. Have you herd of this happening? No I have been looking at the tracker tariff but the calculations are too hard to predict for me due to the price fluctuation. Its much easier to see kwh for kwh at the same rate plus the extra at 16:00-19:00. I am happy to see the calculations if you know how accurately.

[@UpsideDownFork]

@@grantmidd it seems widely reported that real world performance is 10-15% higher than the models theoretically calculate. I did download the historical pricing of Tracker in CSV format and was able to easily compare the savings by bringing my smart meter data and the price cap rates into one spreadsheet. The savings were substantial over the last 10 months but of.course that's no predictor of what could happen in the future.

[@csp6]

Would be useful to state in the title maybe that this is you opinion when already having solar. If you have neither solar or a battery, just getting a house battery is a good option - it'll pay for itself faster than getting solar and is cheaper. Getting both doesn't help that much financially but is an option if people want an off-grid solution.

[@UpsideDownFork]

Every situation is different, I presented mine as a little case study. Others will benefit from batteries to a greater or lesser extent that I could. It's tricky to make broad statements like "just getting a house battery is a good option - it'll pay for itself faster than getting solar and is cheaper." because that isn't the case for many people. It also depends on the timeframe that people are planning for. If you're looking at the long term savings, solar will typically beat most battery systems. Much of this will depend on the roof available though. Battery systems don't have as many variables and restrictions as solar can.

[@alanclark2584]

dont think its the price on the fogstar batteries that really low, more like the price on all the others is being inflated. Saw loads on similar batteries on Alibarba for prices circa $600 for 5 kw/hrs. However it seems known brands like pylontec wont import to uk at these prices direct but will to say south America.? something clearly fishy going on.

[@dougle03]

All depends on how much you pay for a battery. Factory batteries are more than twice as expensive per storage kWh than a DIY setup. It's never been easier to build your own and 15kWh of raw cells from China can be had for a little over £1k, add to that some cables and a BMS and you're at about £1,200 for 15kWh, or £80 per kWh...

[@UpsideDownFork]

That sounds like a bargain but my wife wouldn't be too fond of a battery shelf or table taking up garage space!

[@Orentas01]

@@UpsideDownFork DIY battery can be same small size as factory battery and twice cheaper, so I would call everything 50/50. Just for testing I build 7kwh battery and size of it is same as factory 5kwh battery and I spent only +- 800$ and mine DIY battery has smart bms, 5A active balancing and CAN communication, everything as factory batteries just much cheaper + i was sucked in this hobby and now planning get extra solar panels and more battery capacity to go full off grid, because if you know and interested what you doing you can get really cheap on solar. It’s not true like many say on internet, solar and off grid with batteries is expensive. That depends on many things or it’s expensive or not. My father is electrician, i am electric cars mechanic and probably that’s why i can make off grid system very cheap, and not many people have knowledge about electricity and choose factory parts. And those will be all ways more expensive compared with DIY

[@calysagora3615]

So much this. In my off-grid village, those that has converted to Lithium has paid around 3x what I built my system for. Insane how people waste 2-3-4K because they didn't take a moment to figure out how the system they depends on works.

[@UpsideDownFork]

@@calysagora3615 How much capacity do you have and where did you source your components from to build your own?

[@dennydewaal137]

@@Orentas01 you are right about that . I’m a spark to, and off grid since 2016

[@richardoliver4904]

the value proposition for solar panels and battery has certainly changed since octopus raised the export to 15p, removing the impetus to consume solar power, i simply export since my economy 7 tariff is virtually the same at night, hence charging the battery at night is no worry. This means the size of the battery can be smaller, only required to cover one days premium daytime pull from the grid, I'm not suggesting you are wrong but for me the battery is a key component of my energy management system and if purchased at the right size and price is definitely cost effective. During the summer i split my modular battery and duty cycle each half on a weeklyish basis to reduce cycles and increase life. After 3 years my pylontech is still reporting a SOH of 98%

[@UpsideDownFork]

Thanks for the comment! It sounds like you are well on top of your calculations and are definitely making the most of your situation!

[@MrButuz]

Your generally talking a 10 year payback unless you go supercheap DIY. I've started to do it different after a year of a grid tie battery I am moving to an off grid system that can still charge from the grid on GO night rates but powers the circuits in the house permanently from the solar inverter - the benefit is I still get the ~10 year payback (and estimated profit year 11-20) but if the power goes out - my house stays on my panels still generate, which is quite a big benefit in the future, I think over the next 10 years the grid will be more expensive less reliable and rolling blackouts are a possibility. Also it's fun like a hobby for me - and people spend more on golf clubs and they're pretty useless in most daily scenarios (handy in a zombie apocolypse I suppose...)

[@UpsideDownFork]

Thanks for your comment and sharing your experience 👍

[@JohnR31415]

I managed to get my electrical costs down to 7.5p/kWh for 2023, and that includes the standing charge. Thats a huge discount, and puts my cost last year substantially lower than I could have got without it. ROI (not the only reason to have a battery) is currently 5 years…

[@UpsideDownFork]

Thanks for the comment. Good to hear you've been successful. Are you comparing against the price cap rate or the Octopus Tracker rate?

[@JohnR31415]

Taking my previous split of usage with Go, and applying that to the current rates. DFS really starts to add up as well, December ended up with average cost of under 4.5p including the SC. My expected payback is actually shrinking, it’s under 5 years now, because whilst the import savings aren’t as substantial, the export bonuses are substantially higher.

[@MikeGleesonazelectrics]

If youre having solar pv and a battery to charge up overnight you will need 2 inverters.. 1 for the solar to take the dc and one for the grid to take the ac, commonly referred to as ac coupled. I understand the sunsynk will do both tho so this may be the way to go, could start with 1 batt and add a 2nd if needed later. Personally i wouldnt plan using any unknown batteries like this Fogstar until it has proven installations. You could always start with just the solar side at first with cabling installed in readiness and see how you get on, now that vat is being removed for battery retrofits.

[@UpsideDownFork]

Thanks! That's exactly what i'm thinking with a sunsynk hybrid inverter and solar panels now and add a battery later in the year or as funds allow!

[@pmac6584]

It is probably best to keep an eye on the compatibility list from octopus. The last I saw there was only 2 home evse units Ohme was one of them. The car list is a lot longer but my bmw i3 is listed but it has known bugs that sometimes end the charge before 100%. It is a bit annoying but I have coped because I like the savings applied to both house and car.

[@UpsideDownFork]

Thanks, i'll keep looking at it.

[@joewentworth7856]

we came to the same conclusion. 7kw arotherm ASHP +2.7kw solar PV. we decided to try a year and see what the data said. With simply timing the DHW cycle , dish washer and washing machine (our biggest flexible loads) to times of higher PV, we reduced our exports to 50% of of out total solar (2600kwh for this year) with export rate of 15p I could not justify the battery. Also this is financial. The battery currently adds relatively little environmental benefit, compared to the HP and PV. the excess PV will be used and reduce gas use. my feeling is the battery would be better left for use in a commuters car where it could have a significant environmental benefit.

[@UpsideDownFork]

Amen! We're singing from the same hymn sheet.

[@BlackCountryLad]

All Octopus export rates are now 15p including Go. We charge the battery every night at 7.5p. Batteries are a first for me.

[@UpsideDownFork]

Thanks for the comment. I've responded in this video: kzbin.info/www/bejne/nYebXn-Jm7N8h8k

[@stuartburns8657]

All Octopus Go export rates are not 15p. Intelligent Octopus Go yes, the 'normal' Go tariff is 8p

[@BlackCountryLad]

@@stuartburns8657 you make your choices, We are on Intelligent Octopus Go. Monday to Friday we used £1.81 and exported £15.01, cannot wait for summer.🤣🤣🤣

[@davesoton20]

£2.5k for the Seplos Mason 15kwh on Fogstar as well, or their 15kwh rack for £3k. The biggest problem at the moment is the 15p export rate which came in during the energy crisis. I don't personally think this will carry on for much longer as electricity is so cheap at the moment compared to what is was and has been for many months now. Doesnt make sense they would pay people more for export than it is for a customer to buy a unit. As you know from Tracker, its not much difference at the moment. Will 4p/kwh exports be returning? Probably not, but staying at 15p.... I doubt it. So I personally think that's where batteries make better financial sense or like me that doesn't get any export so have to store in battery instead. Although since my install cost many thousands less than hiring an installer it would take a lot of year of export to make back the difference.

[@UpsideDownFork]

Thanks for the comment. I've certainly made some big assumptions and will have to take a gamble in one direction. If I install solar only now with a hybrid inverter, it gives me the flexibility to add a home storage battery if the export rates fall. 0% VAT on batteries also means i'm not pressured into installing the whole lot in one go.

[@justinwelsh9880]

You need to look at how much power you use, if you use a lot of power to charge cars, heating, water heating then the battery will power the house all day and must of the evening from April to October if you have solar, battery will charge all day, clouds come the battery will power the house, I have had a Tesla power wall and 10kw of solar for 4 years and it’s paid back, put the spread sheet away and go for it you won’t regret.

[@UpsideDownFork]

Thanks for commenting! I've got no doubt that in your case it will have paid for itself. We've had a couple of years of batteries being more financially advantageous than ever. BUT ignoring the calculations and leaning upon confirmation bias is not an effective financial strategy. The figures don't lie, if you don't have an EV and depending on your house load and usage profile, battery storage right now will not yield a ROI. I have a video which goes much further into this issue here: kzbin.info/www/bejne/nommmo2tobmooZI Thanks again for the comment.

[@terrymackenzie6784]

On Intelligent Octopus Go you get 7.5 cheap rate import and 15p export. On this tariff I can do 5k miles in the EV and run the house for net zero cost of electricity over the year, this year may be even better.

[@UpsideDownFork]

Thanks for the comment. What devices are currently supported on the intelligent tariff?

[@terrymackenzie6784]

@@UpsideDownFork ohme Zappi or wallbox car charger or compatible car I have 3.8kw solar and FoxEss hybrid inverter with 15kWh of battery works very well on IO-Go tariff

[@UpsideDownFork]

@@terrymackenzie6784 thank you 👍

[@ecoterrorist1402]

You Do have a lot to learn, my best advise would be get a electrician in your area to quote you a battery install there are to may variables in your calculations, & you are missing additional items - Labour - Charger - BMS - Fuseboard - Isolation switches the upshot is batteries do work and the avg RIO on units i have sold is 7-10 years also what people forget is there demand in the winter is different to the summer - this needs to be calc into any RIO

[@robinbennett5994]

That's true, but those things are only going to put the cost up.

[@ecoterrorist1402]

@@robinbennett5994 it's the only way to get a VAT free Battery

[@UpsideDownFork]

Thanks for your condescending comment! The factors you raise are things that further decrease the financial viability of a battery system. All quotes i've seen are based against the price cap tariff, not the tracker. That is for sensible reasons as we don't have a crystal ball, but the other tariffs can equally go up and down. Also they do not compare against the opportunity cost of investing the money elsewhere. compound interest on a 5-7% investment over the 7-10 year ROI period you mention would come to a very significant amount of money. Different usage profiles may lead to different conclusions, but for our house with our consumption, I can't see a home battery currently working financially.

[@robandrews9826]

I'd only recommend it if you're running out of battery a lot and using a high amount of peak power But obviously, on tracker there aren't cheap and peak periods, you might be better staying as you are unless you go on flux, agile or go

[@UpsideDownFork]

Thanks for the comment!

[@henryowens3611]

If you've got gas lpg, then no, if your boiler and cooker are electric, its some thing to think about

[@UpsideDownFork]

Thanks for the comment.

[@B0jangle5]

Is your usage value accurate? I thought you only recently had a heat pump installed so you might not being seeing the true usage rate. Thanks for the info on battery sites, I hadn't seen those so will redo my own calculations. Edit: noticed the comments about the 0% VAT from February 2024: I still suspect home battery prices will drop even more as V2G and battery tech improvements come in. The second hand market could also be busy as people move their energy storage from their home to the cars.

[@UpsideDownFork]

Thanks for the comment! We were using 2500kWh prior to heat pump life and that is forecast to use 3000kWh per year. We'll see on that one! I am very keen on V2G as our car does sit on the drive pretty much all day, every day!