How to size a home storage battery

[@nickmarshall7019]

Excellent video. I started with 6.5 kw solar and 8.2 kwh battery and found battery running out during the day in the winter months. The battery is only 6kwhr useable so I have just topped up with a new 9.5 kwhr battery which is 100% useable giving me 15.5 kwhr. What a difference it has made with grid import down at below 1 kwhr per day this winter. I used to charge the battery overnight on cheap rate and whilst still having to do it when there is no solar, the frequency of charge has also reduced. I agree with going big on battery size and solar. The biggest surprise has been the free hot water from the EDDI. In 550 days of having solar I have used the gas boiler only 10 times to heat up the water!

[@EVPuzzle]

That sounds like a great solution you've got and paying dividends with its free energy. Eddi hot water is awesome, I hate drawing from the grid for hot water but needs must in December and January

[@nickmunton9606]

I've stopped using the gas boiler to heat hot water - overnight electricity is cheaper, especially when taking efficiency into account.

[@stuartburns8657]

Our 6k solar and 8.2k battery system (5k inverter) was installed mid September. Presently on Octopus Go, and since late October, we've been regularly charging the battery to 100% each night. Our base load is quite low at between 180-220w. Family of four in a 4 bed detached home. I did contemplate increasing battery by adding another 5k, but want to see how we fare during the worse period first. Also (ours is mostly Givenergy) the battery output is limited to 2600w. In order to increase the output you need to add another inverter (so I was told) which I wasn't keen on. A little bit of common sense with main / hungry appliance discipline goes a long way, and the tumbler and washer can always be set to run during happy hours if necessary. Perhaps down the road I may look at one of these Eddi diverters, but then we'd also need the water storage fitted and plumbed. Inverters typically last about 10 years I've heard, if this correct? I'm putting some of my funds aside each month for it going pop somewhere down the line..

[@chrisrebar2381]

Want to help the grid ..... are you kidding me, the "grid" has been ripping us off since its inception - why would anyone want to "help the grid"?

[@stuartburns8657]

@@chrisrebar2381 maybe the excess energy produced with 'help the grip' ie you, by reducing the likelihood of power cuts...

[@markpurcell4507]

Great video, nice to hear the considerations from an end user rather than a salesman with a vested interest.

[@steverdooley]

Very useful video. I went through similar thought process and decided on a factor of 1.5 times average usage, so 15kwh battery for average usage of 10kwh. Only installed for a few months but seems to be working out. Definitely think about the three parts of the year. Summer - we will be self-sufficient in both electric and hot water - no mains usage. Winter - just charge the battery in the overnight cheap rate and let solar do what it can to cover daytime load and recharge. Spring/Summer- partially charge overnight and top up from solar. One big advantage of oversizing: if you are installing a complete system it is free of VAT, if you add an extra battery later it is plus VAT!

[@stuartburns8657]

Yeah, got a 6k pv and 8.2kwh battery mid September. Pleased with it, but wish in hindsight I'd have also maybe added another 5k battery as part of the original install vat free. Hindsight eh?

[@adrianflower3230]

Thanks, Nigel. Some good ideas to help with the calculations. Great work, keep it up 👍👍 I am 1 week in to having Solar connected. It's an E/W facing roof on a smaller detached house. I've gone for 12 West facing and 7 East facing panels - All I could fit given the roof shape. On Monday we have a 5KWh battery arriving. Looking forward to seeing how this helps with the overall aim of reducing pull from the grid. I will use this winter and spring to see how it works, and consider adding another 5KWh battery next year. I remember your earlier video well with advice about just using less electricity first before buying batteries. We only use 2750KWh a year at the moment as a household, but well see how this changes as we adapt to having the solar / battery available.

[@SuperJCBDigger]

Thanks for a really useful video. While I understand people's obsession with payback times, the other thing to consider is the additional value you've put into your house. Should your ever sell your house you'll definitely get your investment back and make it more attractive to potential buyers. I mean, given a choice of two identical houses, one with an electricity bill of £3000+ per annum vs around £300 a year it's a no-brainer

[@EVPuzzle]

You'd think so but some still think, yuck solar panels. Their loss

[@steveoswald63]

Absolutely the best DIY I've seen this week.

[@divad4438]

Don't know if you have already said, the flexibility of having a battery/size for running a load when the sun is intermittent to keeping a high KWH item running while keeping you off the expensive grid tariffs is useful

[@MarkyMark1668]

Thank you Nigel. Great advice to enable me to focus on my requirements. Reasonably straightforward now that you have broken down the process of recording the data to enable an effective decision.

[@katebygrave]

Thank you for your well thought out video. We installed our panels and batteries nearly a year ago now, and had similar thoughts. Now we live in Portugal, which is somewhat different. Approximately 300 days of sun per annum and you can’t sell back to the grid. But the same logic still applies; understand what you want from the system, work out your peak daily use, and size panel production and energy storage accordingly. We have been off-grid since March and we consider we have the balance. By the way, I’m a Norfolk gal, and I can hear a slight lilt in your speech, but the picture of Elm Hill confirmed it to me!

[@DanEVSolar7]

I think for me a key consideration as well is future proofing. I’ve gone for bigger than I need with the expectation of buying an EV (or 2) in future and possibly a heat pump further down the line. Seems like more and more things are going to be using electric going forward.

[@Nalesa-Energystorage]

Yes， and the energy storage integrated machine has appeared on the market now, and its capacity is very large, 15-35kwh.

[@richardteychenne3950]

Good video, you are quite right with all the options at the end of the day it is about finding the solution which makes you feel most satisfied. This is a balance between what you can afford and what gives the optimum savings in returns and environmental benefits.

[@johnrush3596]

Good video as always. I have to agree, sizing of the battery is a case by case basis. When I started looking back in 2019, my primary goal was to be able to get through the evening and so I went for a 16kwh system. Now with electricity prices as they are, getting through a dull day on the cheapest electricity available has become the priority, hence shifting from 21kwh usable to 25kwh , the extra 4 is to balance things on those dark days. Being able to charge cars or hear water and run the house without pulling from the grid at expensive times has proven to be invaluable. The install I have can cope with 7.2kw of load, which with the 10kw solar can mean covering a 10kw of load (7 from battery, 3 from solar) on an october day. So as you have said, this is about what is needed for your case, and one size does not fit all.

[@TomThomas-jj9tq]

Can you charge all that capacity from zero (or close to) in winter in an off-peak period? If so, what inverter/charger are you using?

[@johnrush3596]

I have two single phase AC 3600 lux units. This means max charge rate of 3.6kw per unit with a max of 12kwh (ish) in a 4 hour period.

[@TomThomas-jj9tq]

@@johnrush3596 I'm thinking of a Victron Multiplus 48/8000, with 15kWh batts initially but then doubling to 30 when budget allows.

[@rugbygirlsdadg]

We use less than 10kWh/day on average, and we're retired. We've just had 10kW of panels installed 5/5 on an East/West roof with a 35° pitch. Two 5kW string inverters and an Eddi. I also have a Zappi, but only need to charge the car once a fortnight, if that. I've turned off the gas hot water and use appliances as much as possible during daylight hours. I have a 10kWh Libbi with 5kW charger/inverter on back order (subject to price). One of the issues that needs to be considered is battery inverter. Microwave (900w) plus kettle (2.8kw) plus oven (2.5kW - 4kWh on boost) means that a 3.5kW battery inverter won't hack it. This is going to be a learning experience for me between now and when the battery arrives.

[@EVPuzzle]

Nice low usage so your solar and battery will keep you running without any grid use most of the year. Tiny bills here we come 👌👍

[@powerguymark]

Thank you for your video. You bring up some interesting points.. that being said. I simply disagree about your charge that we need to use less energy. If we're talking about energy from the grid I am in complete agreement. However, one of the biggest advantages of even having a solar installation is the freedom to use energy to enhance our lives. If one's system is properly sized energy usage no longer impacts the grid. Obviously, it's not practical to design a system that will be 100% grid independent 100% of the time for days and weeks on end, so airing on the side of caution is always wise. I SAY: " LET SOLAR POWER SET YOU FREE!"

[@EVPuzzle]

Very true , it is an enabler but freedom Vs wastage has a line . Balance is good

[@duncancarroll1091]

Morning New to this game, had 12xJA Solar 405w panels, a Solis 3.6kw hybrid inverter and 2x 5kw PureDrive batteries installed early August, so not much data yet…so far, I’ve only imported 49kwh (approx 6% of my consumption) since the system went live and living in the central belt of Scotland I’m expecting this to increase over the winter months…more to follow as my data set expands… Like the videos….

[@martingough8538]

Hi Duncan I'm in S Ayrshire so was interested in your data. We have a 5.85kW system, but are still waiting for our 10kW Puredrive battery. Who knows when it will arrive. Can I ask why you went for 2 5kW batteries rather than one 10kW one? Thanks

[@duncancarroll1091]

Afternoon Martin… 3 factors on the choice of batteries…. Availability, ability to daisy chain thereby increasing capacity and redundancy… if we lose one battery we still have a partial system…

[@campbellcopeland]

I’m in the process of a similar sized array but looking at one, likely two GivEnergy 9.5kWh batteries and 3.6 hybrid inverter. Based in Glasgow, think the second battery might help more in winter.

[@karencarpenter8275]

Really interesting real world example. Great video and shows the complexity of the calculation. No idea yet whether our calcs are correct - 11.6 kw system with 2 7.2 kw inverters and 2 5kwh batteries on a 3 phase supply with an ev! Plus English weather…. Too any variables…..

[@EVPuzzle]

Solar sounds great so presume you use lots of energy, battery though will be the challenge, how often do you run out and are you happy running out. Electric heating is a killer as it uses energy outside solar hours

[@blackhoundrise8431]

Thanks. We just had solar panels installed Wednesday and now looking at batteries.

[@teranova5566]

Hi, write some more info. What is the peak power? How much did it cost ? What PV panels and inverter? ...

[@peterhughes1827]

what about the VAT?

[@edwardpickering9006]

So I've already got 106kwh of batteries sitting on my drive (Ioniq 5 and Peugeot e2008 - soon to be an MG4) and one of them is usually always plugged in during the day. That said Myenergi's new Libbi looks mighty tempting...

[@eliotmansfield]

i went from 4 x us3000c pylons to 6 x us3000 pylons and went with a parallel 5000va multiplus so I can charge in the four hour window, because as you say a single victron wont do it. Great thing now is that I can invert up around 7500kw - which means whatever I have running in the house, i never pull from grid. Crucial thing is a use multiple jump cables from the pylons because they too thin (25mm2) to support sustained high current. I use a jump cable for each pair of pylon 3000’s and it all stays cool now

[@EVPuzzle]

Parallel inverters. Nice and totally agree on cable sizes, gotta be cautious with big loads

[@LookatBowen]

Eliot, who supplied and installed your setup? This sounds like a great setup.

[@linlithgowcc]

Another great video. Esp as it focuses more on the different aspects you need to consider more than just pure math. We don’t use a lot of elec and have 2kwp solar which is still exporting a lot to the grid. Yes, an EV can consume that excess but only at above 1.4kW surplus. We’ll charge the car off peak from the grid and focus on a 5.2kW battery balancing the solar surplus and the minimisation of peak price elec from the grid. we can always add another battery and scale up as we learn, but don’t want to over purchase or oversize as all consumerism has a carbon impact. Having a smaller setup also helps you to challenge your use a little and not assume a high consumption lifestyle can be solved with lots of bling.

[@ShortVersion1]

Yesterday, Tesla support gave me the option in my app to import/export to powerwalls, as opposed to only using them in support of solar. Very excited to see what difference that will make financially, as it dumped 29 kWh into the grid last night as soon as peak arrived. If we charge at .07 and export at .22, something tells me it won't be as simple as just multiplying the difference.

[@bengardener8928]

It's not worth it until the UK offers net metering sadly as it will cause your battery to cycle alot more and thus degrading the life of the battery.

[@JohnlynHD]

Thanks for posting. Great video. Having a 4kw stand alone system with 9.6kw of battery and it’s being fitted in the next few days. I already have a 1.8kw system 11 years old giving me maximum price on feed in tariff. That’s having a new inverter and replacement panels. The 9.6kw batteries were a guess. I’m considering adding a 4.6kw battery to my 1.8kw system also. Going to start recording how much I’m generating on the existing and the new system then will decide where to go next. But this video will save much head scratching. John

[@EVPuzzle]

Makes so much sense doesn't it. You know far more than me as you've reaped those FIT benefits for many more years than me

[@leeumney7675]

Great video, as usual, I had 3x Pylontech US3000C's installed when my panels and inverter were installed BUT, I've just bought 3x US5000's to join the 3000's, giving me around 23kWh. My 8.5kWp array may not be able to charge the batteries fully during the winter (unknown since only having them installed in March) but top that off with Agile and I should be good. I've started testing a couple of infrared panel heaters, my wife loves the one under her desk and I have a 720W one in the conservatory which I'll use when the temps drop enough.

[@leedove7255]

I have a 5.5kw array and a 5kw battery. I can't charge the battery to full on most winter days (5-6 months a year) from the array

[@leeumney7675]

@@leedove7255 I've had one or two days this month where the batteries haven't charged BUT this has been when there's been the dishwasher, tumble drier, washing machine, computers, xBoxs, etc, all running, etc. I look at what the panels and battery also save me, on a day when there's 30kWh used in the house and I've only drawn 80-10 kWh for instance. Over a couple of months alone that would work out to be a massive saving.

[@leedove7255]

@@leeumney7675 I am not saying that you will not save with the system just that the batteries seem a bit big. I am a bit confused by your numbers (30kwh used and drawn 80 - 10) do you mean 8-10 ?

[@leeumney7675]

@@leedove7255 I know mate, not saying that you were. I went oversized for 2 reasons: 1. in the winter I can charge them with both grid (Agile) and what little solar we get. 2. in the summer I'll be able to maximise the amount I get back by strategically dumping power onto the grid when it's paying the most. I also plan on getting more infrared panels and the extra batteries will help with those over the winter.

[@andylees2940]

I would love to know more about your pylontech battery choice esp as you have looked at quite a few. Very useful vid on battery sizing thankyou

[@Jaw0lf]

In the winter, my solar production does not even cover my home use, so even a good 10kWh of solar would not provide energy for the home. I found my Tesla Powerwall 2 would top up overnight and be used during the day and evening, helped by any solar production. I found my night use of the cheaper tariff was at 89% so it certainly saves a lot of money if used correctly. Also in your calculation you stated your solar equalled the size of your battery, but it must be remembered the home will be consuming some of that solar energy!

[@stephenshannon3706]

Excellent and though provoking video - thanks for your efforts. For those with an EV, keeping spare capacity in the car is very useful especially given that car battery sizes can be far larger than permanent domestic storage. How long before most cars become a fully integrated part of our grid balancing system?

[@loicminois8072]

V2Grid , V2Home are projects in the box of oem car company. Planned to costumers in 2 years, maybe . But think about why Tesla doesn’t offer V2G , mystery ..

[@bennydeglin1474]

Maybe becaus of the free charging of first Tesla models.

[@lmlmlmjm]

I've had 9.9 kw DC battery storage and 6.8kw solar for 18 months and recently added a further 3.3kw. As a Go customer if you charge your battery at night you can only charge at 3kw so at most I can only charge 12kw at the lowest cost. So any more battery storage could only be charged at full cost. I found on the worst solar days with 9.9 I would sometimes drain the batteries towards early evening. Though managed an average of 6.08 pence per kilowatt cost most of last winter. Batteries are great during winter using low cost night charging when solar is low but if you have solar the batteries hardly ever get used during summer months so usually stay over 70% charge with 100% most of the day when the suns up. No need for any low cost charging during the summer. Not sure of the charging speed of ac batteries.

[@johndoyle4723]

Thanks, a good discussion. I just about manage with 7.5Kwh, but the payback of adding more is way too long, but I still wish I had gone for 10 Kwh. In summer, no problem, and surplus generation from my 4 Kwp is just dumped to my ev. In Winter, I fully charge the battery on the cheap overnight rate. Load shifting helps keep me going. I just about manage to keep my day rate grid unit cost to about 1 unit/day, but the savings from extra battery are way too long. Everyone is different. Heating is still gas, and living in a very old house, there is little chance of further gains.

[@halifaxenergy]

Would have been helpful to know the size/age of your house, and # of peeps in house. Txs. You brought up some very astute points (like the EV pre-charge) - and the urge to conserve!

[@CheshireRing]

We're all different, but I found some of the points in this video very theoretical. I have an ASHP, underfloor heating, electric vehicle charged on a home wall box, 6.4kW solar, and 13.5kWh Tesla battery. No gas or oil. Most winter days in our 4 bed 2021 build detached we consume about 50kWh, 60kWh when the average 24 hour temperature is down to 1 or 2°C (or lower), about 40kWh when it gets above 5°C. In winter, the solar output is pathetic, about 2 to 3 kWh per day in December. So we charge the Tesla domestic battery overnight on Octopus Go off peak (which lasts 4 hours) at about 3.5kWh per hour. We also run the underfloor downstairs heating fully during off peak, and the ASHP can run at up to 3.8kW to achieve that (especially in sub zero temperatures). The wallbox for the car charging consumes 7.5kW, and other demands (electric heating in the bathroom, for example) lift our overall consumption to about 15kW per hour in the off-peak period. That is about 70amps, so the first point to check is the actual fuse size for your electricity supply. The box probably says 100amps on the outside, but the District Network Operator may have installed a smaller fuse because of local network inhibitors. For about 120 days of the year in winter, we could use two Tesla batteries. That would allow us to get an additional 11kWh of usable off peak capacity (Tesla recommends not depleting the battery below 20%), so on our current tariff that would enable savings of (40p full rate - 12p off peak per kWh) = 28p per kWh x 11kWh per day x 120 days = £369 per year. On current prices, that's a payback period of 20 years +, which is longer than the lifespan of the battery, and we would need a 20kW supply. In summer, our daily usage, excluding car charging, can often fall below 20kWh. So we only need one 13.5kWh battery to cover evening use after the solar has stopped. We charge the EV either from overnight off peak or trickle charge from solar (in summer). In an ideal scenario, we would probably have about 15/16kWh of USEABLE battery storage, but since Tesla only makes one size of battery.... As the video says, we're all different. You might want to run air conditioning during summer days, or you might want to keep a reserve to cover for external power cuts. I would never seek to charge an EV from a domestic battery, because in many cases you might be putting the charge through two inverters, one into the domestic battery, and one into the car battery, with a loss of about 10% each time the supply is fed through an inverter.

[@garyzimmerman8679]

Other considerations to consider lowering your electricity usage, and depending on where you reside. Is the use of Tankless water heaters, or using natural gas/propane to heat your water and heat your home as well as to cook with. Here in Texas. I am use a propane tankless water heater, and my central heating is running off propane. Propane is cheap in Texas. However, the issue we have is the A/C usage in the summer. While our u it is on, it draws 5kw as long as it’s on. We also use a propane generator to charge batteries in prolonged bad weather. Where the bad weather has knocked out the power grid. I use propane to off load electric use to allow for smaller batteries and less panels. I use around 6000 kWh per month.

[@EVPuzzle]

But my point to using electricity is to avoid oil and gas products. Burning any gas isn't a good thing going forwards. 5kw for AC. Ours ticks over at 400w and peaks and 2.6kw. (2 x 3.7kw and 1 x 2.7kw units)

[@hooksforestchin]

Partly why I've gone with the Pylontech batteries (& your recommendation), as not sure what the solar will generate (install of both in November) against our usage. Heating/water still has, so daily usage not that high. Will see how it goes and add additional batteries if required. The solar install is the expensive thing (~20% of our cost is scaffolding) so get as much of that as you can when first doing it. The other bits are easier to upgrade or add to

[@HansKeesom]

I do this on an outlet basis. Started with my kitchen as that is the main area that needs to continue to run when grid is down. Testing my need is a matter of turning of the grid for as long as I can deal with it :-) I started in my kitchen using an Ecoflow River 600 with 768 wH inside and an extern 1500 wH external battery. It can run some bais appliances in my kitchen like a fridge and a inductionhub on lower settings. So I can heat some food and charge some small devices. If needed, it can also run the heater of my house which is on gas but does need up to 50 watt of electricity to do so. I charge it from AC but on a sunny day I turn that off to profit a bit from my solar. Only like two panels which is fine in grid down situations. These panels are also connected to a grid-tied-inverter so they are always able to dump their yield into my home grid. Using a 1-2-both switch on the MC4 solar cable to do this, also allowing me to send more to the battery's. Do mind the voltage that the mppt-charger can deal with though* Now for my kitchen I want some more wattage, so looking for the Delta 2 so I can run 1800 watt devices even when the grid is down and have some more storage. The old system will then just run the internet and my working at home spot, which one also want to keep alive when grid down. * I solved that problem by having a victron mppt charger that could deal with the voltage from the panels and have it charge a 12 volt battery. That MPPT-charger also has a load port that can be programmed for a certain voltage range of the battery to open up. To that port I have connected my Ecoflows in my home, so they only get charged from DC when there is enought voltage in the 12 volt battery.

[@EVPuzzle]

Sounds like a clever system. Having portable or non grid tied batteries really helps. I'm. Planning a garden room system but that'll have a portable battery that can double up as an emergency system for the house

[@HansKeesom]

@@EVPuzzle Outside near my panels I have a 12 volt battery that had heatmats to keep it warm in winter. From the load port of one of the MPPT controllers I have 12 volt lines into my house connected to my portable batterys that are both AC and DC connected. When AC drops they will start charging from the 12 volt battery immediately.

[@EVPuzzle]

Would love to see a diagram for this setup 🤔

[@fergusanderson5307]

Thanks Nigel, great video, so useful. I'm another Norfolk boy here! Aged 65 living in an old and cold Grade 2 listed farm house. Planners not keen on roor top solar. Probably not living in this house for a long time. EV arrives in a couple of months. Looking at batteries initially I "think" that solar will be more expensive if we have to do a barn roof install (East/West panels as ridge is North/South) = more panels plus the roof is not good. Field solar install I think might be more expensive due to cable runs of over 100m. Looking at batteries as being more transportable if we move. Then looking at Octopus Agile to shift daytime consumption into batteries, charging batteries at off peak along with EV. Whats this like as a plan? Ps subscribed!

[@EVPuzzle]

Cheers Fergus, I'm still in favour of solar over battery if you can only have one but that does depend on whether you can use the energy without exporting it. Listed buildings must be a challenge. I'd go ground mount, if you have space maybe a helio tracker or two for optimal performance. What EV are you after? We've loved the Cupra since testing it.

[@fergusanderson1852]

@@EVPuzzle OK, will look at ground mount solar a bit more carefully then! I'd be interested to hear more from you on solar options - perhaps on Norfolk installers. Listed buildings a bit of a nuisance when listed churches are being considered for roof mounts and govt continually talking about promoting roof solar. We have black pantiles and some of the new black solar panels do not distract from the overall look of the roof i feel. We ordered a VW I3 Pro Performance Family with Asst Pk+ on 7th Jan 2022. Probably due in March 2023. Seems as if VW have been the most disorganized and of all car manufacturers through Covid and chip shortage problems. Also the software seems to be worse than other brands. However I think as a car itself, it is reported as being spacious, quiet, comfortable for long drives and not too big. Nothing is perfect but I am happy to stick with what I have ordered - especially with the Matrix headlights and other extras build into the Family model that were withdrawn from the options list about 5 months ago. If you are happy to chat via messenger that would be OK, Can I PM you?

[@scottyboymu]

Hi great video and very informative 👍. I've now fitted a Ac coupled giveenergy invert and 9kw battery although I'm struggling to get hold af a WiFi dongle unfortunately, any ideas where might still have them? My solar array has been great since it was switched on yesterday and the the weather has really been great. I believe we were exporting from 7.50am until sunset so am excited to get the battery commissioned.

[@MrSensible2]

I'm a low power user typically taking 5-6 kWh/day. I went for a 3.16kW array & a 3.3 kWh battery. Had I known what I know now, I probably wouldn't have had it put in. The battery discharge limit is typically 2.2 kW. Put the kettle on first thing in the morning or put the oven on in the early evening & anything above 2.2 kW will automatically get drawn from the grid; that's even if the battery is full. Likewise, there are occasions when the battery just refuses to deliver current. In the wee hours, it seems to give up for maybe 15 minutes at a time & the base load (fridge, router, etc) all comes from the grid. Also when wifey uses her hairdryer, sometimes it refuses to play ball. It's really annoying when you're away on holiday & the system has virtually bugger all to do, that you see the system pull 0.7 kWh/day from the grid! Yes, money-wise this is no big deal, but when you're already a low user, it's not insignificant & totally undermines the overall economics of solar.

[@3dmotormaker]

You should call this channel "EV & Energy Puzzle"

[@EVPuzzle]

I should have predicted it better

[@nickbea3443]

if looking to use the battery for peak time use - morning shower or cooking in evening - don't skimp on peak power rating of the inverter. If you can't get enough kW rate from the battery/ solar (esp. evening with oven/ microwave/ induction hob) then you'll revert to grid. G99 rated inverters will let you export the rate that the DNO dictates but allow higher power draw around your property if suitably matched.

[@thomasevans7792]

Thanks for your content Nigel. I'm currently researching the best option for my NZ passive house. My latest thought is going for the Tesla Powerwall mainly so I can one day join the Tesla Energy Plan which I hear has great returns compared to the normal 12-17c NZ per kwh. What are your thoughts on the Tesla Energy Plan?

[@EVPuzzle]

Don't know much about it but heard good things from others recently, makes sense for battery control

[@geoffreycoan]

Thanks for the advice, I’ll run the calculations and see what it says for me. Our solar upgrade (a further 10kW of panels on top of the FIT 4kW) and battery is due to be installed in a weeks time. My sizing rationale was to fit as many panels as I could to the roof as it was more cost effective to do so whilst the scaffolding was up than incrementally add panels over the years. On the battery we’ve gone for twin inverters and a 5.2kW and a 9.5kW battery. The larger battery I just bought the biggest I could as £ per kW it’s cheaper the larger you buy. I do know that with our Air Source Heat Pump we can use up to 30kW in a winters day so the battery wont cover all of that but it’ll make a big dint in it. One gotcha I became aware of is that a lot of smart meters (mine included) are only single rate smart meters. So can’t get an overnight rate tariff without changing the meter - for which Eon want £130😢. I may just end up having to swallow this cost for the overnight charging flexibility, but it’s annoying nevertheless

[@EVPuzzle]

Older smets1 device maybe?

[@geoffreycoan]

@@EVPuzzle I don’t *think* so. How would I be able to find out? I specifically confirmed that it going to be a SMETS2 meter when it was fitted, which was only in October last year, but then a week after it was fitted, my electricity supplier Symbio went into administration and I got moved to Eon. Ever since then I have been trying to get the smart meter commissioned as it had somehow fallen through the cracks of Symbio/Eon. Eon tell me that it is only a single rate meter and “most smart meters fitted are only single rate as most customers are on single rate tariffs”. Seems incredible penny pinching to me if that is the case

[@bertiesworld]

@@geoffreycoan I find that hard to believe in this day and age. I had a Smart meter fitted April 2022. Not only is it 2 rate meter (I have E7) but it is already set up to read exports. Long before I even thought about going solar. Commissioned? I presume Eon is actually reading it or do you have to supply a reading? If so Eon should be able to change it to what tariff you need. Certainly my supplier has done updates over the air to the meter since it was installed. I would suggest though, working your way through the various menus. I actually queried as to whether my supplier was actually reading 2 rates, as all I could find in the main menu was one single reading i..e. a total dial, plus an export dial. It was only by going on through various menus that I finally came across one that displayed first 1 the day rate and then the night rate. Complicated, not so smart!

[@geoffreycoan]

@@bertiesworld It turned out to be a very long complaint story with Eon that 6 months since I wrote the above is still not quite resolved. The key point is that Eon CANNOT change your smart meter from single to dual rate over the air. Other suppliers apparently can but not Eon! I had a smart meter installed by Symbio shortly before they went bankrupt and I got moved to Eon. When they installed my dual rate smart meter they didn’t fit an external antenna on it and so as we live in a rural area it never worked. Eon believed that I had a single rate meter so after 10 months of them ignoring my emails about the smart meter not working I finally escalated it to a complaint and a man came to swap the smart meter for one with an antenna. However as Eon’s records showed I had a single rate meter they configured the smart meter as single rate ! I fortunately had photos and videos of the old meter so could prove that I had a twin rate meter that they had downgraded…. and then I learnt that Eon can’t reconfigure the smart meter as single rate!! So back to the complaint and they have now been out and swapped my (working but single rate) smart meter for a dual rate non smart meter. As I proved that this was what I originally had they waived the charge for this. I’m now waiting for the next appointment to swap the dumb meter dual rate meter for a dual rate smart meter and I’ll be sorted. Hard to believe but it’s all true

[@geoffandanncooper234]

Hi Nigel. I really liked your battery size video and have just subscribed to your channel. I'm researching quotes for a Solar panel veranda + roof panels + battery + EV charge point up at West Runton. Can you recommend an installer? BTW have a large GSHP fitted last December to replace the Calor Gas boiler - much cheaper. But it ruins your garden!!!

[@EVPuzzle]

West Runton, almost on our doorstep. Have you tried Leaping Hare electrical in Syderston near Fakenham. They Installed my Mixergy tank and do solar installs too. Nice small family run business & thanks for the sub to the channel

[@frasersimpson8264]

One important factor I'm not sure you covered (if you did I missed it) is that the battery might be say 10kW capacity, however since you very rarely would run it till it's flat and battery makers usually suggest only charging to 80% to help them last longer, that means that although rated to 10kW, it's more realistically like 7kW of usable storage, so as someone else in the comments suggested I would say you're better off doing your numbers, then going 1.5 times the size to cover the charge capacity and also degredation over time which will also reduce capacity.

[@EVPuzzle]

Many batteries are now 100% DoD, mine is 95% 80% fill doesn't apply to lifepo4 that's more relevant to ncm car battery tech But yes there's an element of capacity not used , 10% for me

[@Nalesa-Energystorage]

Yes， and the energy storage integrated machine has appeared on the market now, and its capacity is very large, 15-35kwh.

[@blackcyclist]

Have really enjoyed your videos. Taught me so much. I think I've worked out now that a 6.5kw is the right size for my usage (not the 3kw my 1st quote was for). This allows me to expand later if I need to. Trouble is, can't get anyone to quote or stocks are gone. I'm ready to go Solar PV + battery, but no-one available to service me. Frustrating, but now I'm thinking I buy the equipment & hang tight till I can find a fitter.

[@williampelzer1460]

I did this and you're going to struggle to find a fitter if you do so. The other problem would be that your install and equipment will be around 20 - 25% more expensive just because of the premium a fitter will charge and you're also losing the vat exemption. I'm not advocating that you wait but I would say if this is what you want make sure you go into it with your eyes open. Another thing to think about is system design, look at the panels you would like and then decide what roof mounting system you want and go to their website and use their design tools to give you a bill of materials for the fixings and rails. That will also allow you to see if the panels will fit onto your roof and whether the system size is feasible. After that decide what inverter you would like grid tie (string or micro) with battery or hybrid and what size you need for the panels and expected load. Lots of variables to consider I've got two US5000s, I'm aiming for 6kw solar and using a Victron MultiPlus-II 5000va 4kw battery inverter with 3.27kw on the house roof 1.8kw on our extension and a further 1.8kw on a gazebo in the back garden the last two strings on an AC coupled solax dual mppt grid tie inverter. Just waiting for roof hooks to get the roof install done and the rest should fall into place.

[@blackcyclist]

UPDATE: I've found a company & have signed up for a 4kw PV system and a 6.5kw battery. Thanks for all the tips & info

[@EVPuzzle]

Brilliant news

[@blackcyclist]

@@EVPuzzle Trying not to get "buyers remorse". Hoping you can offer you take on the difference between having a 3kw hybrid inverter or 3.6kw? does a 3kw make sense with 4KW panels? Then finally, if I decide to add another 2kw of panels a few years later, should I be getting a higher KW inverter now, to allow for expansion? (or cross that bridge & add/upgrade the inverter if/when needed?) Thanks in advance 😁👍🏿

[@EVPuzzle]

Unless there's a big price difference which I doubt, go 3.68 then worry about extra panels later. Or put extra on now?

[@RBcymru]

It also depends where in the UK you live as some parts will get more sunlight / sunny days. I had a quote for a 6kW solar array plus 3kw battery at a cost of £12k (£1k for EV charger on top). The issue I see is that in the summer I can't use the 36kwh I will potentially produce per day as the rear roof of my house faces due south. The national grid pays more during high demand which is actually in the winter when its not so sunny. I am considering a 2.4kw array at ground level (on a shed roof 6 x 400w panels) with a 5kwh battery and 3.6kw inverter. I want to power a home office and charge / top up my EV using the 13A charger as it can charge at 2.4kw easily. My car isn't my main vehicle as I use a van for work so car can sit charging 7 hours a day. Do I apply for G99 and grid tie the inverter or simply add a change over switch in the home office to run of solar system or from the house ?

[@MarkSmith-wc1ek]

I have 8.2 battery I was thinking of getting another one but looking at quotes it will be more cost effective to add more panels another inverter and battery also it I will be able discharge at higher rate

[@johannappel9582]

Really helpful information. Some time ago I watch your video where you considered installing the Puredrive battery system. I gather you didn't go for the Puredrive in the end? Can you please explain why not. I have accepted a quote to have a Puredrive battery with Solis inverter installed and I am having second thoughts. Many thanks.

[@EVPuzzle]

I didn't believe Puredrive themselves would be around long term or the product would have a long support life. Going with just the battery and a solis is much better idea than their own inverter imo

[@cbromley562]

Good video. Although, Tesla Powerwall gives out consistent 5kW power with 7.5kW peak. Comfortably handles heavy start up load, such as fridge/freezer etc.

[@EVPuzzle]

Depends on Dno approval

[@cbromley562]

@@EVPuzzle Yes, it is the case that there’s a cap on inverter output, based on the off chance that the full power might zap the grids transformers for a couple of milliseconds. Our cap is 10kW and that means that our 5kW Solaredge inverter combined with the Powerwall’s 5kW is the maximum for our area. We’re lucky, as some people it seems are are capped at 2.4kW. Although the combined export from the Solaredge and Powerwall is capped at 3.6kW to the grid, the Powerwall gives 5kW into the house on-grid and off-grid. Admittedly, when we installed solar and Powerwall in 2018, the ‘backup gateway’ wasn’t available in the UK. With the standard gateway the battery was throttled to 3.8kW into the house, but when we upgraded to the backup gateway (when it became available), the full 5kW capacity was unlocked…plus improved functionality and control.

[@michaelgnaedinger5915]

Thank you, nice overview very helpful.

[@EVPuzzle]

Glad it was helpful!

[@philipsuarez986]

Tricky as we charge two vans every night plus we are heavy users. Our lowest daily load may be around 20kw but typically 60-70kw. Trying to install a big enough battery to cover this would be uneconomical. The annoying thing is we have 100kw of batteries sitting in our drive but no vehicle to home functionality

[@richardhaywoodh]

Good stuff. Can you Island, run all your house if the grid goes down? or do you only have specific circuits that will run purely from battery/Solar power (I understand many solar systems will not function if the Grid supply goes down and many buyers do not know this or ask about it as they assume they can run their house on solar)

[@EVPuzzle]

My house runs OK without grid power. It's a design choice with the right battery. Mines not perfect of course. Think I'll improve it over time

[@JustMeTalking]

Hi Nigel... I think he's asking if your setup is Grid-Tied. It shuts down completely during a Grid Outage. Or have you got a 'Gateway' setup that islands your house so everything can continue to work?

[@EVPuzzle]

As I said my house runs OK without grid power, it's grid tied but isolates from the grid when there's an outage to ensure no bacK feed

[@JustMeTalking]

@@EVPuzzle That's interesting, how does that work? Is it a manual switchover?

[@EVPuzzle]

Automated, if it detects the grid isn't their it physically opens a breaker preventing back feed.

[@edwyncorteen1527]

One thing not mentioned is look at the output power of the battery, a small one will not be able to fully provide the power for a kettle for example, somewhere around 5kW is fine for most people, this requires a larger battery, as you have done, think big!

[@EVPuzzle]

Mentioned it on the inverter side just presume no one is buying a bigger inverter and small battery but yes they both need to be capable

[@nonstop7726]

Great explanation 👏

[@SheepShearerMike]

When vehicle to house, and vehicle to grid charge points are available for the public to buy in the UK, that will make pence per kWh a lot more affordable. I am looking at buying a salvage Leaf with 24kwh battery for just £1000, even if the battery is only half the health, it works out about £80/KWh, instead of the home battery at £800/KWh!

[@EVPuzzle]

Are there salvage leafs for £1000 with battery?

[@SheepShearerMike]

@@EVPuzzle I think so, I have been looking on Copart and there are a few Leafs that pop up each week, although I haven't seen the final bids, so maybe they shoot up just before the auction ends. I am planning to buy one in the next month or two so will let you know. I have made it on to the short list for the Indra Vehicle to Home trial, and as I sold my old Leaf, I will have to buy another!

[@SheepShearerMike]

Even if you bought an old Leaf with half battery health off Auto Trader at £5000, it is still about £400/KWh, instead of a home battery at 800.

[@roversberg]

handy video..! what about dynamic ess? mine is a victron instalation of 4kwh solar and at the moment a 5kwh battery, my coverter is 5kwh and i am using 6kwh a day in the summer and same as you, 24kwh in wintertime..so i need to get to what size battery? and is it possible to disconnect batteries in the summertime to expand the lifetime of the batteries? cause in wintertime i charge them in the night when dynamic prizes are at there lowest and there is no sun.

[@RonvanDriessel]

Dear Nigel, Your videos are so informative, thank you for sharing. I'm about to invest in storage batteries too. Possibly in combination with a Victron Hybrid inverter/charger like you are using. In several video's you mentioned that your batteries are charged either by excess solar or by importing from the grid at a low tariff. Is this selective charging done automatically or by daily manual settings in your Victron inverter/charger? Please explain about how you manage this and were you found information on how to program the Victron inverter/charger or other device that controls the charging behavior of the Victron. As you mentioned in one of your video's some time ago you would prefer this intelligence in the battery solution what was not (yet) available at the time of recording of that specific video. I would like to have this automated if possible by means of scripting in smart home automation like Homey Pro. P.s.I already have a Solaredge inverter plus 14 kWp solar panels. A Zappi EV charger is also running here ;-) I run Flows and scripts in Homey Pro to make use of low tariff hours (each hour is priced differently at my energy supplier) for running the air to water heat pump to heat the boiler. I am also waiting for a solution by Myenergi to boost Zappi charging at low tariff hours automatically. Cheers, looking forward to your reply. Ron

[@EVPuzzle]

Ron When the time of year arrives I set victron to charge at 230am the start of our cheap period and finish at say 60%. Some days that might not charge at all if we have nor than 60% left. By being in charge mode though the battery won't respond to loads so I can heat out water or charge the car at 230am without draining the battery. I tend to set once and just leave it after the first few nights needing a boost. I haven't seen a programmatic method for changing the timers

[@3dmotormaker]

I installed PV and battery so that I can carryon as I am - just at a cheaper price.

[@laurencedamazer2260]

Hi, Your videos are fantastic, thank you so much. Just got lost on your logic here. Dec 21 you stated you generated 94kwh for the month and 250kwh in Jan 22. I think this is on a 5.8kw system before you upgraded. This averages about 10kw per day over the 2 months, no problem. However in Dec 21 you averaged just 3kwh per day ( say upto 4kwh per day with the increased size of 9.3kw), so how are you saying your solar plus 18kw of batteries will cover your usage of 24kwh? Am I missing something? I live in Norwich and currently since system went in 20/12/2022 average about 2kwh per day on 5.8kw panels, it can only get better?

[@GarethJones-dk9yp]

Great video. Lots of info. I'm like you I've gone a bit OTT. But u really utilise the Go tarriff. I would be interested to know how you manage you night charging? Do you look at Solar data for the following day? Or do you just charge at max amps every night?

[@annagluba4994]

Hi Nigel, great work!!! Would you recomend where to get pylonthec batteries and vitron inverter? Regards

[@EVPuzzle]

If it suits you yes, its a more complex system though so be aware

[@annagluba4994]

Would you recommend any installers?

[@EVPuzzle]

Afraid not my installer no longer does residential work

[@loicminois8072]

Thanks, very usefull video !! A Quick Compare : SOK or Pylontech US5000 battery rack 5kWh , which is the better ? An advice ? (Prices are very close)

[@AffordablePC1]

very well explained sir...

[@tmd63]

The biggest issue I have is that my home uses 500W/h nominally and there are a few peaks of around 30minutes to an hour of 9kW when the shower is in use (stepson uses it way too long) or the microwave/toaster with 3kW each I have solar panels of 3kWh MAX but the inverters do not run high enough for the max loads. Instead of the 500-700W average.

[@Alan_UK]

Another informative video Nigel. I may of missed it but I don't think you mentioned the degradation over the life of the batteries. E.g if it was 20% over 10 years then a 10kWh system will only hold 8kWh. So if the need was for 10kWh then one needs to add 25% = 12.5kWh. I know the % is stated by the manufacturer but I suspect the manufacturer's % are derived through stress testing and extrapolation and will vary by manufacture and that the reality maybe better or worse than expected. EVs have proved less that had been feared but they may be less stress than a home battery system.

[@EVPuzzle]

There's some good analysis on an Australian battery research site showing pylontech Do well degradation wise. Im expecting these to last my life Nd I'll be so old I won't notice the drop off🤣 I hope

[@tommyjakobsen5504]

do you have pylon batterys.. how many do you have on your setup. i have 4 of h48050 2.4KW for my Solax X3 5kw setup. but we have heatpumpe air/water and used in October to febuar about 40KW pr. day. mostly is for the heat pump that are using about 30kw. alone

[@EVPuzzle]

Yes 5 x us3000c

[@flotsamike]

Our experience has been that if the battery is only intended to store electricity from your solar panels there's not much point in the battery size being more than three times the rated output of the panels in kilowatt hours.. Our system has a battery capacity that's equivalent to 1.5 times the installed capacity and it often runs out of electricity in a 24-hour period . On our best days if we had 30% battery storage we could use all of the solar power we generated without sending any back to the grid,. But if the batteries were any bigger we would never make enough power to run the house and charge the batteries completely. Our house uses between 5.5 and 6.5 times the installed capacity each day in the summer which negates the longer days, so if you're somewhat overpowered with panels a bigger battery might make sense to help you through the cloudy days,. We live 32° north of the equator and I'm sure folks further north might have longer summer days but averaged over the year it's unlikely you would be able to store more power. In our case our solar system generates 5-5.5 times the installed power a day, so subtracting what the house uses from that leaves what the battery can possibly store. On the other hand if we had less than 10% of our installed power we would need help from the grid a lot more often which would make the solar panels less useful. Budget considerations sized our battery for us. Because we live in a hot climate that's also cold in the winter we tend to use 70% of our electricity during the day to run our heat pumps and the other items in the house which have not been tweaked to maximum efficiency yet. In a place like the UK you might want a large battery to store up night rate energy to use during the day and have solar there just to help you stretch out your batteries over the day. On a grander scale if every house could store 30% of its energy per day at night then, power generation could be levelized in that the plants would just make the same amount of electricity all the time and the batteries would handle the peaks.

[@ChampionCCC]

it's all very well sizing the battery, but to get that size has to make financial sense surely, especially if or when paid for exporting back to the grid. I bought 200Ah cells from AliExpress. So about £1k for 10kWh of battery. Another £200 for a Seplos BMS. That just about makes sense financially, but many batteries are £1k per 2.5kWh, which I cannot see being financially viable

[@EVPuzzle]

Only if that's your priority

[@rolandashdown4903]

very helpful breakdown - thanks,

[@maggiem57]

I need to know more...I am having real problems with my giv energy 5.2 kWh battery. It is only charging to 2.7kWh and they keep recalibrating it to try and "push" it into full capacity. I accepted their suggestion of going into the firmware fix experiment, but again, oh we need another calibration.. At what point should they give me a new battery

[@EVPuzzle]

I'm afraid it's a common problem I'm hearing. Not sure how best to advise people but I know some are receiving refunds and removing the battery

[@wlhgmk]

Just a thought for the folks that are concerned about the planet. How about using batteries that are not based on Li. There are a number of possibilities. Using Li for static applications is driving up the price due to supply and demand and making EVs unafordable to many of us. And alternated technologies, while the don't have quite the cycle efficiency of Li batteries, have much much greater lifetimes.

[@richardmorgan6457]

I don’t have solar as yet but want to take advantage of the overnight Octopus low rate. I’m going to use Pylontech batteries. How do I work out the number of batteries and inverters ?

[@DTech101]

Battery I would love a battery but they can’t get my system finished yet still waiting for the inverter to get installed, the price of the battery will soon get ridiculous and they get greedy and start pushing prices up. I’m off of the battery wagon for a while now 😢. On a side note did you get the Shelly installed?

[@EVPuzzle]

Yes shelly working

[@jonnyb9604]

Nice video, Nigel. I've been looking at the Victron Pylontech combination too. I'm starting to get my head around all the Victron models. What made you get a separate GX module? I see they make an inverter with it built in.

[@EVPuzzle]

In case it needs replacing, easier if seperate. Didn't seem to be a cost benefit either way. I built gx isn't as capable either, less ports and less cpu power

[@Ray-ki6fs]

When you’re pulling from the battery inverter, is it a sine or square wave output?

[@EVPuzzle]

No idea Ray. I know some inverters are sine wave others aren't but what the difference is, is beyond me

[@Ray-ki6fs]

Well Nigel, square wave inverters are often categorised as 'dirty power'. The square wave creates noise on the mains and can cause reliability issues with your home equipment over time with all the clipping. Obviously a sine wave output is the clean option, but is normally costlier.

[@wino99999]

I would think any inverter grid tied to the mains (ie in parallel to the grid supplying your mains) is going to be as close to a sine wave as possible. A square wave o/p wouldn't meet the standards for connection! All solar PV inverters are sine wave and have to match frequency and phase, I don't see battery inverters being any different!

[@EVPuzzle]

Gotcha

[@matthewwakeham2206]

Victron inverter is pure sine wave. Square or modified sine wave is just for cheap inverters these days!

[@ndudman8]

As off grid, which I know you don't really talk about... (and I'm doing that coz i like diy and avoiding bureaucrats) then the bat is the best way to soak up excess solar.

[@vinylnutter]

How much will 2 extra batteries cost with installation?

[@party999acb]

Thanks Nigel. going back a few vids can I ask (we've got a 5kw Huawei Fusion inverter) been looking at Luna's. How did you get on with that 5kWh battery you had on loan. looking at possible going for the 10kWh (2x5kWh)

[@EVPuzzle]

Battery was excellent. Fast response and easy to install. I had issue with the hybrid pv inverter not being good in low light conditions. App wasn't great at timed charging either but that might have improved now

[@party999acb]

@@EVPuzzle beginning to understand about the inverter have 5100w array with a 5kw inverter (in-place just short of a month) living out here near Bangkok (Monsoon season) only averaging 15.6kWh of generation daily some days as low as 3.6kWh hoping this will improve going forward

[@LookatBowen]

Thanks for the video Nigel. No solar in my solution, just batteries. I've painstakingly recorded in a spreadsheet peak consumption times and average consumptions for the Day, week, month, year. My needs are to cover the peak tariff and use the octopus go faster to charge batteries from 21:30 to 02:30. We would also charge the car at this time and run the washing machine or dishwasher. What about the inverter? Which inverter size is needed for say a 17kWh battery. The thing I'm struggling to get my head around is, let's say I have a full battery 17kWh, and I turn on the kettle for 1 minute (smart meter shows 3kW spike). Has it used 3kW of 17kWh battery or 3kWh/60*1 ? Also what does the inverter do? What is its point? Another example: I switch on electric shower. It shows 8kW spike on the smart meter. Let's say I shower for 5 minutes. Is it using 8kW of the battery or is it using 8kWh/60*5 ? Would I be able to run the shower at all on a 4kw inverter. If my average daily consumption is 13kWh then would you recommend a 17kWh battery?

[@EVPuzzle]

Think you're almost there. KW is power now. Kwh is power over time, usage, capacity. Inverter is needed to convert or invert from DC power in the battery to AC power in the house. Yes 3kw for 1 minute or 3000wh/60 = 50wh (0.05kwh) of energy from your battery

[@EVPuzzle]

17kwh battery for 13kwh of usage is a big battery. If you could add some Solar you wouldn't need such a big battery

[@Dreador.]

I was also looking to do this - Battery only no solar as going battery first makes the solar payback look a lot worse when you could charge at 5p. BUT (big but) Octopus have pretty much blown this out the water now removing the Go Faster Tariff and replacing it with 00:30 to 04:30 Go tariff - You might be in luck if like a few you can move onto Intelligent as that still offers a fairly big window to recharge up (6 hours at 10p) - Now Ive revisited my figures as I cannot move onto Intelligent it looks like Solar will be needed in my setup.

[@nickbea3443]

Think about combination of big draw items to perhaps plan your inverter size? They are unlikely to coincide with cheap off-peak grid price.

[@peterhughes1827]

@@Dreador. you want to have some solar at the same time to avoid VAT

[@jonnyb9604]

I see what you mean about the GX module. Another thing: have you looked at wiring a switch to automatically change from grid to inverter in case of power cuts? It seems automated products are very pricey for what they are, whereas a beefy 4-pole contactor in a nice box is under £200. Would such a switch work with your inverter charger?

[@EVPuzzle]

I need a switch to isolate the inverter to go on grid not the other way around

[@howardadams4072]

Have you given any thought to a minimum SOC in case of a power cut?

[@DrRussell]

Very good question

[@EVPuzzle]

No power cuts are so rare plus using 90% is even rarer

[@ndudman8]

Have you seen the v2g or v2h... I think there is a french company that has just released a ccs charger that also does v2[g/h] sounds like a better option than buying of getting too bigger battery... just use the cars one if you have access... or need a bit to take you over those cloudy days.

[@markpurcell4507]

V2G/L is very interesting technology but is still a number of years away from being supported on inverters and cars which is when it will become useful. Home battery storage is also important to cover loads when your EV is not at home.

[@ndudman8]

@@markpurcell4507 Yep... and home battery is I think also important... I was looking at the price of the French new ccs, not cheap, but cheaper than buying a 60kwh battery that you'd never use... so you could just add, when at home your car onto the capacity of dedicated home solar battery. I was interested, already have 15k battery, but would be nice to capture a bit more and use when cloudy... or if the cars not used anyway for a few days.

[@EVPuzzle]

Good for grid balancing and occasional use but I don't see it as something I want. I'm constantly trying to add kwhs to the cars not draw from them

[@kwent3]

How big your inverter for all your system or you have multiple inverters?

[@brianholding4357]

Hello, Nigel; Do you happen to know if it is possible to add home batteries systems from different company's? For example, could you now add a Tesla PW into your system! I know you research these thisgs to great depth, amd wondered if you have looked into this at all, it's a bit beyond me to do so. I currantly have a SolaX 10kWh pack, and want to increase the capacity, but I think my installer may have stopped trading, as I'm getting no replies. Thank you for taking the time to read this. ...........Soryy, the reason is I want to delete gas, and fit an electric heating only boiler, I want to store 20kWh of over night rate electricity, and use this for heating. Thank you for all the info you supply.

[@AllElectricLiving]

Tesla powerwall is 5 kw charge and discharge nigel, ❤

[@EVPuzzle]

Not all apparently some restricted to 3.6kw

[@phil_nicholls]

@@EVPuzzle not quite right Nigel. The Tesla PW will nominally always charge at 3.3kW, if it can meet its objectives by doing so - if it determines that a faster rate is needed, then it will charge at up to 5kW. It can always discharge at 5kW, and can, for a short burst, discharge at up to 7 kW. Each extra PW adds to the capacity, so two PWs can charge at up to 10kW, with a peak of 14kW. HTH (I did reply earlier, with a link to Tesla’s own page on this, but think you have ‘auto-delete’ set on for any posts containing links - a quick Google search on Tesla PowerWall Charge Rates, will lead you there though).

[@JustMeTalking]

OK... you're all wrong, and right. I've got two Powerwalls (27kWh) and a Gateway 2 Each Powerwall discharge rate is limited by DNO Approval. So some properties are restricted to around 3.6kW continuous discharge by G98 regulations. With a G99 Application a Single Powerwall can be ramped up to discharge at 5kW continuous max. Our house is G99 approved for two Powerwalls discharging at 10kW (with short surge periods higher than that). Tesla Tech Support can change these settings remotely based on your G98/G99 Approval specs. With regards to charging. We can charge up to 10kW with the Powerwalls, but the AI determines this

[@phil_nicholls]

@@JustMeTalking Oops! You’re quite right, I’d forgotten about that process as it was all done for us by the installer. My bad!

[@olej24]

Great video. I thought the PW charged at 5kwh though? Hopefully get mine within the next few weeks. Been on order since Feb!

[@EVPuzzle]

Depends on configuration and whether you have G99 approval for 5kw

[@olej24]

Thanks for clarifying. Just checked my G99 and I’m approved for 5kw. It wouldn’t make too much difference anyway as I’m currently on octopus intelligent tariff and get 6 hours overnight charging so would have plenty for the lower rate. (Even though I’ve only used solar to charge since march)

[@aldozilli1293]

I don't understand how payback cannot be the most important thing? That is except for people like me who live in a village that suffers from regular outtages so an off grid back-up has a practical value?

[@EVPuzzle]

Money isn't everything to everyone . Lots of people keep loads of money in non interest paying accounts 🤷

[@aldozilli1293]

@@EVPuzzle what I meant was, unless you are off grid, the purpose of a battery is to save money, whether that be by charging night rates (using in the day and/or selling back to grid) or by not wasting the solar over-generation. Either way the end goal is payback.

[@jcf828]

Great content. Thanks

[@FiscalWoofer]

So just done a calculation on how much electric I’d need instead of oil…turns out we are using over equivalent 15000kWh of oil! Would converting this to electric even be possible in medium size house?! Plus we use 5000kWh of electric per year. So I calculate to get solar to cover this we need a 20kWH array the works at full capacity 2-3 hours ‘every’ day! In Wales is that even possible! Even if oil quadrupled in price which I think it will…it seems oil would still be cheaper over next 10 years compared to buying batteries, panels install etc?!

[@EVPuzzle]

Oil has fair amount of inefficiencies so your 15000 might convert to say 12000 then improving COP value of 2 or more average would reduce you down further to maybe 6000kwh. It's definitely possible to go Electric Keep humidity down and it'll be even more efficient Adding solar will reduce your costs and a battery can Really help in winter, staying off expensive rates A good installer is needed of course

[@FiscalWoofer]

@@EVPuzzle thank you this is useful and seem a little more achievable! Of course the big up front is the now install for later gain.

[@rugbygirlsdadg]

A word to the wise. Some buildings insurance does not cover panels...

[@EVPuzzle]

Not mentioned in my t and cs. When hardwired it becomes infrastructure and covered within the melting pot for the house. Hardly a high risk item tbh whereas oil tanks with rusk of leaks and cleanup, some insurers won't insure you at all with oil

[@rugbygirlsdadg]

@@EVPuzzle that's not true for all policies. Mine had a specific exclusion for panels. It basically said "PV isn't covered"! It's worth checking your policy and with your insurer.

[@vmanthani]

You had to go for G99 application?

[@EVPuzzle]

I did yes

[@davinmullan]

When you say not to oversize, I have build 48kWh battery from2x 2015 nissan leaf 24kWh batteries. i only intended to use one 24kWh battery but when offered a second battery I couldnt say no!

[@EVPuzzle]

Very sensible, never turn down an extra battery. What inverter and bms are you using?

[@Cypher007vUK]

i recently saw a post on FB that showed a US2000 that had burst. its put me off them a bit to be honest, that and the fact im struggling to find any installers that either recommend them or will install them. they all seem to want to use Gro watt, Giv energy, etc. also how long do think before prices return to the correct levels? i had a Giv 8.2Kwh on order back in Jan 2022, installer could never get any stock so gave up in April, that was £4k with vat, as no solar on it as have a 4kwp already.

[@EVPuzzle]

Prices will rise, that's inflation, salaries won't reduce even if electricity prices do in a year or two Pylontech are very reliable, much mirbthan givenergy from what I'm seeing

[@Cypher007vUK]

@@EVPuzzle problem is my salary in the public sector has risen maybe 0-1% over the last 12 years. this year it jumped because the minimum wage went up.

[@EVPuzzle]

It's a real problem. People think batteries and EVs will get cheaper, I suspect not, but whilst you can if you can. We'd need deflation to see prices go down sadly

[@jhonathanabrachaen5170]

Size matters

[@chrisrebar2381]

"...clean energy. .." - True, shame about the cobalt and lithium!

[@matthewwakeham2206]

How are you limiting your export with all the different systems?

[@EVPuzzle]

I'm using the energy, not limiting export

[@jamesstaplesv]

kilowatt hours meant nearly nothing to me, Amp Hours is the main issue. I calculate 25,000 for my basic needs per month.

[@John.strong]

As per the hot water thing Its far cheaper to store hot water than store electrical energy So, add more hot water cylinders... They are cheap.

[@niallbenn]

Couldn’t you just start with 5kwh system and add ass needed. Seems like a lot of systems are easy enough add to?

[@EVPuzzle]

I definitely support a modular approach for that reason

[@keithhobbs1]

I think you used to hit a problem that additional batteries attracted vat at 20 percent. But now it's zero rated it might not apply. Might be worth checking before going down that route would be my advice.

[@thomasjohnbirks132]

Octopus no longer offer an off-peak tariff. You need solar PV.

[@philippadobson1589]

Not true - Eco 7 is still available and the suspension on Go & Intelligent is temporary whilst they work out what to do about the reduction in fix from 2 years to 6months.

[@thomasjohnbirks132]

@@philippadobson1589 Really? Who is offering Eco 7 at this time to new customers?

[@philippadobson1589]

@@thomasjohnbirks132 I have my smart meter going in next week - I was told (by octopus) to talk to the engineer and he might put it directly on the dule rate. If not, then I just need to give them a ring and it might take a week or so..

[@thomasjohnbirks132]

@@philippadobson1589 Thank you.

[@johnbow100]

I've had a 4kw solar system for a few years and receive FIT payments. Can anyone tell me if installing a battery at this stage will affect my FIT payments?

[@EVPuzzle]

It won't if AC connected

[@kroozer5215]

Hear me out here please - Lets say IF you could run a generator off hydrogen : Have you ever thought of how you could charge those pylontechs during winter ? with say a genny that was basically really really cheap to run and kept somewhere where it would not be heard ? would you/could you and if it was doable how would you make the connection to the batteries so it all went through the houses fuse board - all done safe, ive seen it done in the US but not here in the UK - Well not with a domestic dwelling