Should You Buy a Home Battery? Beginner's Guide!

If you're considering a home battery then hopefully this video will help demystify things for you. It's a big and complicated investment so make sure you choose the right one for your circumstances and make the best use of it once installed.
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[@Muppetkeeper]

Thanks for the video. One thing to note, you also need to consider the power of your inverter and the duration of your off peak tariff in order to determine your maximum battery size. There isn't any point buying 40kWh of batteries if you can only charge them cheaply for 4 hours a day at 3.5kW, because the most you can charge is around 14kWh.

[@SpeakToTheGeekTech]

Good point, I mention power in terms of discharging to your demand, but I neglected to mention speed of charging them.

[@se62hy]

But it does mean you can store more solar etc. So it can make sense.

[@geoffreycoan]

A good walkthrough of key points to consider when choosing a storage battery. I’d just add that you don’t need to have a battery system that delivers 100% of your house needs, you need enough to take the worst out of your electricity tariff. We have Octopus Agile, a large house with 18kW heat pump, only 2.6kW power output from the inverter and just a single 5.2kW battery at the moment. The figures don’t add up but this combo is enough to run us through the peak evening period with maybe a bit of grid draw. Daily costs are typically £5-10. Recently it’s been super cheap, we made 15p profit on 72kW of grid import on Christmas Day!

[@SpeakToTheGeekTech]

I agree, that was kind of my point about choosing whether you need to size your battery to cover an average day or a worst-case day. In your case you have gone for closer to an average day taking a sensible balance between covering a chunk of your heat pump in colder months but not having too much wasted capacity during warmer months.

[@pmac6584]

Good summary. I have lux and henchuESS (18.6kwh LFP) with 4kw Solar. Octopus report that my average unit rate is 8.5p so I am happy that I managed to get it very close to perfect for my current usage. I am waiting for my Ripple Energy wind turbine to start paying out before I look at further changes. I have an EV so the next item is a heat pump. Thanks for the useful videos.

[@SpeakToTheGeekTech]

That’s a good average rate. Roll on Kirk Hill going live!

[@Jaw0lf]

Seemed like a clear explanation of the options. I agree that Octopus are one of the more cutting edge electricity providers and try to give options that work with the newer technology and ideas. Intelligent Octopus, 8kWh of Solar PV, a Tesla Powerwall, ASHP and EV now mean my whole house use, heating and 1000 miles per year are costing me just £100 per month.

[@SpeakToTheGeekTech]

Thanks! And yes I think it's easier to control your costs when it's all electric too - gas was a bit mystical in terms of how much was being used but seeing live power for your heating is eye opening!

[@craigwrigglesworth8046]

Looking forward to hearing what impact your recent heat pump has on your usage and how to balance it with the battery especially if we get a few more 0C or below days. Loving my heat pump but the energy usage rises rapidly as temperature drops so I feel that just looking at peak usage days to choose a battery doesn't scale with a heatpump.

[@SpeakToTheGeekTech]

Yup I'm still compiling data on that. So far the battery is seeing me through most days but we haven't had any seriously cold days either yet as it's been very mild weather.

[@bazcurtis178]

@@SpeakToTheGeekTech I am also looking forward to that. My 9.6 kWh of battery at the moment gets me to around 7-9pm. I will be interested to hear how much more the heat pump will take. I have my Octopus survey on the 12th January.

[@tonyfeasby1437]

Definitely worth doing the sums to help the decision. The currently low price of electric on say octopus tracker + high(ish) interest rates dont help justify a battery but switch those and add in an incentive or two and its miles more viable

[@SpeakToTheGeekTech]

Yup Octopus tracker certainly is a good price right now. Octopus Go plus batteries is still a lot cheaper for me overall but it’s close. I guess the more you use the more they’re worthwhile

[@ianrob4760]

just found this channel and I have to say I spent the cash on my setup (solar, ASHP, Batteries and EV from work) not to save cash as such but be independent from those robbing bastards of the normal energy companies. I am now in a position where until I die I can rely and manage my own usage and Octopus Agile is just brilliant so I never have to pay for peak energy rate again, regardless of what prices may fall to.

[@SpeakToTheGeekTech]

I have to admit that my solar / battery investment was purchased for both eco reasons (reducing our footprint overall) and also to save us money in the long run. They were also a crucial precursor to replacing the gas boiler, helping minimise the overall cost of running electric-based heating. No harm in the solution achieving two aims :)

[@ianrob4760]

oh totally it does that had to wait for battery and now being fitted on Thursday ! ! just 5KW until I can afford a bit more ... then will be set up as for my sausage more than covers the peak hours ! @@SpeakToTheGeekTech

[@colingoode3702]

A timely video. I had solar (4.1kW) & a battery (9.5kWhr) installed last March. After 9 months of use I reckon I need more battery storage, a larger Inverter than the current 3.6kW hybrid & probably additional solar panels as well. As you rightly point out installers only offer what is easiest for them to quote to avoid too much paperwork (G98 vs G99 approval) & to make their quote look the cheapest. My installer originally offered a 5.3kWhr battery & I requested a larger 9.5kWhr because the extra cost was not too much. However, after 9 months of use I reckon I need another 9.5kWhr battery for a total of 19kWhr. As you also said an additional battery is easy enough to add but will attract 20% VAT (unless the rules change). Adding additional solar panels increases the overall cost but means 0% VAT. Replacing or adding an additional inverter adds even more cost & complexity. The reality is I will probably do none of the above because the ideal scenario is just too expensive. I'm currently looking at heat pumps but I'm not sure the cost or upheaval is worth it.

[@tarkadahl1985]

Rules change in Feb, no VAT on battery only installs. But I'm sure installers will have a 20% increase in profits soon after

[@SpeakToTheGeekTech]

Had my heat pump for about 3 weeks now and it's a game changer. Our hands were forced really because we needed to replace the boiler, but so far the extra cost to get a heat pump compared to a boiler is hardly anything in the grand scheme of things and considering we've moved from a really inefficient old boiler to a heat pump, we're seeing maximum benefits from savings on running costs.

[@MattyFreedom]

I had a similar situation. Ideally I wanted panels on my SE and SW roofs. But the installer really focused on doing the bigger side, without really explaining why. I was pushing throughout to do both, but it came down to the fact I would need more scaffolding, another inverter as 3 strings would be required and as I could get less panels on the SW side, the cost of doing it would have pushed the price up far too high. I too had to push for an extra battery to make 10kwh and even though they ended up doing 2 less panels (bird protection not possible if I had the extra two, which is not acceptable to me), I had insisted on at least a 5 kwh inverter. Funnily enough they gave me a 6Kwh inverter in the end, but I won’t see the value of that until the spring. A battery is a no brainer for ensuring you use what you generate, but in the winter it really comes into its own as you load up the battery cheap and use during the day. In the summer you will be able to dump lots of your generation at expensive times. So a big inverter and the proper permission could really make the battery and earner and the bigger it is the better to a point. If I’d had gone for the 5Kwh battery originally suggested, I would have had to consider not using flux as I would use that up before the expensive period without manually reserving battery for it each day or faffing around with home assistant automation. I think part of my original challenges came from using a group buy scheme. They are very focused on templated installs that maximise cost efficiencies to give the best price. I’m happy with that overall, as I’d have probably arrived at the same scenario anyway, but I’d have saved some frustration if a much more honest conversation had been had right at the start, unrestricted by scheme templating.

[@MattyFreedom]

I forgot to say, if you want any EPS you might have set up to be any use, then having a battery that has some charge left in it is also essential. I have just the 2 emergency sockets but the batteries need to have at least 30% to be usable, which in the summer may not be an issue, but in the winter you can drain even 10kwh very easily, leaving you with not enough for the EPS to of use.

[@colingoode3702]

@@SpeakToTheGeekTech Unfortunately I had a new boiler installed just before covid hit in 2019 so replacing it so soon with a heat pump is kinda counter intuitive - at least to my way of thinking. I've also fitted a full Tado control system so I have quite a bit invested in my current set up. I'd love to be able to start again from scratch but that is not going to happen unless I move house. Good to hear above that 0% VAT will come in Feb for battery only. I'm guessing that will build up a big backlog of battery only business for installers. I will revisit my existing quote for an extra 9.5kWhr GivEnegy battery & look again at some extra panels if I can stretch that far. I'm also looking at Thermaskirt (H20 version) as an alternative to up sizing radiators. However, this also looks to be quite expensive & my 10mm microbore pipes don't help either. 35 years ago we looked at doing a self build Potton House with a heat pump (I was in the HVAC industry) but I think I'm too old for the hassle that would involve & finding suitable land in the right location is almost impossible. So a extra battery & possibly some more panels is my best bet or, do I add an extra in inverter as well to avoid modifying the existing 2 strings? Decisions decisions.

[@roguebullet4220]

Brilliant, thank you. Explained very well. One thing though... you mentioned Economy 7, but i don't think you stated that Octopus provide this service. This is the tariff I'm currently on, as i can charge my All-in-One & my car (with a granny charger) on a low rate.

[@SpeakToTheGeekTech]

I didn’t go into much detail on it because the rates are quite high compared to the other smart tariffs. It’s a viable option for a lot of people still though such as yourself obviously!

[@buixote]

We're using a 10kW system from Signature Solar (and KZbinr, David Poz). We're happy with it, and it runs the whole house (assuming we're not trying to run too many loads at once; i.e. stove, microwave, induction hob). We're using their 5kW chargeverter to re-charge the battery outside of peak hours). Unfortunately, we don't have "good sun", but the Inverters (ES5000s) can accept PV input... If you want something less DIY, the Powerwall is a good option, with *superb* software.

[@SpeakToTheGeekTech]

Sounds like you're in the US then? We have Powerwalls here in the UK too which are deemed reasonably good set-and-forget devices, but there's also GivEnergy and many others which are offering similar features at a much lower price point. I have GivEnergy kit myself and love the control I have over it. It's a reasonable compromise between a commercial product and DIY.

[@Joe-lb8qn]

Very timely, I've just started the process of getting quotes for solar and battery this week. Current plan is store cheap overnight electricity in winter months for daytime / evening use (I'm on Octopus Go so 4 hours overnight) and fill it up with solar in summer. For a typical winters day I use about 10kWh so a battery round that size will likely be what I'll go for that would reduce my electric bill by about 2/3 winter and more in summer. And in spring/autumn make a choice each day or week depending on weather as to which to do. You make good point about Go/Intelligent Go, Intelligent seems like a lot of hassle to me and subject to the vagaries of it all working. My charger is compatible but for the time being Id stick with Go I think.

[@SpeakToTheGeekTech]

The second that my charger supports Intelligent Octopus I’ll be switching to it! Cheaper off peak rates for everything and much more generous export rates for my solar! The savings outweigh the hassle in my opinion.

[@phil_nicholls]

We run a couple of EV’s through a SalSac scheme, and they also provide free charge points for the cars. So when we got the second EV we had an Ohme Pro fitted which gives us access to Intelligent Octopus. We charge our batteries overnight (27kWh), along with the EVs, and use that to run the household. Now that they’ve upped the SEG to 15p per kWh, we’re going to export all of our solar (9kW system). Overall, we will be in net profit by around £250 per year. The solar and batteries will pay for themselves in just over 5 years now (down from 5.8 years when we actually used the solar), as we save roughly £3500 per year. Add those savings to the savings we make running the EV’s and not paying for fuel, which equates to around another £2500 per year, and our investment in solar and batteries will have paid for itself in just 4 years! It’s like giving myself a £10k pay rise! Best investment I’ve made! As to Intelligent being potential hassle - we just use the 6 hours of cheap rate overnight - we don’t do any of the fancy daytime charging (the cars aren’t at home during the day anyway)!

[@MikeGleesonazelectrics]

What hassle is there with Intelligent Go?

[@drreality1]

Thanks for the simplified version I loose track when I search when go into details of which battery is Modular, cost per Kwh , investors, local control options, compatibility with EV chargers, UPS option/ power outage Retrofitting Solar later, optimisers inventories 🤯 It’s a mine field with a lot of bad advice online!

[@drreality1]

Inverters not investors hehe

[@SpeakToTheGeekTech]

I'm glad it helped!

[@narrowboatlongpod4176]

i think you covered all the bases. I went for a 5kW inverter as i didn't think 3.6kW was going to cover our use (and it helps with forced export during DFS saving sessions). There is an issue with Intelligent GO if, as is often the case, the battery sees the EV as a house load. If you have a fixed charging schedule then the batteries will supply part of the energy if you get bonus slots. Home Automation usually allows this to be fixed by force charging the home storage during these slots.

[@SpeakToTheGeekTech]

Yup, all down to how the charger has been wired up and whether you want to use home automation to manage it or not. As a side note, the new GivEnergy EV charger combined with the GivEnergy inverters include a special cloud-controlled mode to avoid such drain during those extra hours. I think the myenergi Libbi/Zappi combo can also do that.

[@MikeGleesonazelectrics]

I have intelligent go and there is no problem with the battery as you can schedule both the forced charging period for the battery and the discharge period. Ad long as you schedule the battery to discharge outside of the cheap periods then the battery won't discharge.

[@ecoterrorist1402]

Hi Ya, I would regard myself as an expert in this field with 30+ years as an electrician and 12 years in the renewables the sweet spot for batteries with solar is 6-9 Kwh for the best ROI, long term after 6 years add another battery. Most that I have sold have had an 8-10 year payback based on real data, and not salesman waffle, yes when I have seen customers they have had a lot of rubbish thrown at them. I'm a firm believer that all tech should be set-up and leave, for my customers. It's great news that VAT will be zero on parts/labour this coming 1 Feb 2024. I'll use your code if I decide to go with octopus, looking forward to 2024 Now seen the video, I'll send my customer to this link, before knocking on their door.

[@SpeakToTheGeekTech]

I think with most of these systems the intention is for them to be set-up-and-leave, but the reality is still far from that sadly. They are getting better as time passes but we're a few years off that I reckon - maybe when the technology matures and they become more mass-market. It would be great to see them sitting there, automatically integrated with the energy supplier whenever you switch much like when you swap the SIM card in a phone, the phone just configures itself and starts working with the new network. Until we're at that point, there will always need to be someone keeping an eye on the battery for the user.

[@Dominic_Bolton]

Energy suppliers have different priorities to the end user though. For example they would want to export your excess 4-7pm every day, but you want to hold onto that power for yourself and only export during a DFS Savings Session. In short, best to retain control yourself

[@David-bl1bt]

Sadly I can't find any links in the description for the smart meter data portals 😢

[@SpeakToTheGeekTech]

Oops sorry I'd forgotten to put those in. Thanks for noticing! I've updated the description now.

[@MikeGleesonazelectrics]

I think you should design the battery storage to account for the cheap tariffs for charging during the winter, the summer isnt an issue and there is very little solar input during the colder winter months, so pv input is minimal then. I have an ashp and 2 evs and intelligent go is good for me, 6 hrs or sometimes more at 7.5p/ unit whats not to like?

[@SpeakToTheGeekTech]

As soon as I can get on IO I will, I need me those 6 hours @ 7.5p!

[@MikeGleesonazelectrics]

@@SpeakToTheGeekTech I'm thinking my poor 80A supply cable must get rather warm during those hours! I must feel them if I'm ever up at 6am :)

[@jimmcdonald6465]

Thank you for the video. As someone who was considering a standalone battery I see that Flux requires evidence of solar, which is difficult for me, so this makes the economics too parlous sadly.

[@SpeakToTheGeekTech]

Hopefully there will be battery-only tariffs very soon, I guess Octopus are just trying to encourage the take-up of solar by doing that. Batteries are becoming increasingly useful to the grid so I would expect their stance to change.

[@jimmcdonald6465]

Yeah I wrote to Greg Jackson @Octopus about this very point and was referred by a colleague bizarrely to Flux. Unless things have changed I believe solar is a requirement for this.

[@alanstansfield7707]

When working out the required battery capacity you also need to allow for the minimum state of charge of the battery. Most batteries should not be discharged below 10%, which reduces the effective capacity of the battery.

[@SpeakToTheGeekTech]

Yeah, a lot of batteries such as the higher capacity GivEnergy ones are 100% depth of discharge though, so there's hidden capacity within them which means it's safe to discharge to the 'fake' lowest level (which is 4% visible to the user)

[@ricobass0253]

My battery installer has set the minimum battery state of charge to 20%.(I think this is a general recommendation to maximise the life of LiFePo batteries) So, although I have a 10kWhr battery I can only use 8kWhr. This is important when working out what capacity to buy. I was not aware of it.

[@SpeakToTheGeekTech]

It really depends on the manufacturer of your battery. 20% lower limit is extremely high, usually there's a 10-15% buffer split between the top and the bottom levels of the battery (so you get a 90% or 85% depth of discharge battery). It's not normal for your installer to set an extra artificial limit of 20% for you - your battery management software should take care of it for you and you set it as low as you like! On GivEnergy for example, their 100% depth of discharge batteries, such as the 13.5kWh all-in-one is really almost 16kWh, but the 2.5kWh extra is hidden from the user as a buffer to ensure the health of the cells. I can drop as low as 4%, and the battery management software keeps that 4% as an emergency for its own use.

[@HappySnappyChappy]

How big are they? How heavy are they? How expensive are they? What do they look like? Do they have to be inside? Can I fit them myself? How long do they last? How dangerous are they?

[@SpeakToTheGeekTech]

Contact an installer, get a quote. See what they recommend you install, Google for pictures and specifications and that’ll answer most of your questions! No they don’t have to be inside. You can’t install them yourself if you want to take advantage of export tariffs. They last at least 10 years, probably double that with reduced capacity but the tech is too new for us to really know yet. And LFP battery chemistry as used by GivEnergy and the latest Tesla Powerwall 3 is extremely safe.

[@LG123ABC]

What if your main concern is just avoiding annoying and inconvenient power outages? In parts of the US it seems that our electrical grid is becoming more unstable -- with rolling blackouts/brownouts and other outages. Ideally, I would like to be able to run everything in my house for at least a few days if there is a major outage.

[@SpeakToTheGeekTech]

If you’re in the UK then a GivEnergy all in one and gateway or a Tesla Powerwall are probably the best solutions for running off grid. If you’re in the US then I’m not so sure… I’ve heard people just get a Ford F150!

[@TheRonskiman]

@@SpeakToTheGeekTech Victron all the way, far better than Givenergy, Tesla etc. The Quattro comes with built in changeover relays, I had my incoming mains diverted to the garage, through the Quattro and back to the house. It can supply 8kW (there is a 12kW version too), so can run the house in the event of a power cut, we have 29kWh of batteries, how long they last will depend on SOC and solar. We always charge off peak at 8kW, but as we are on Flux we only get 3 hours, so doesn't fully charge the batteries in that time. We export maximum power in saving sessions, so earn a fair but there, also export at peak (but not currently due to sdaving sessions. So far my gas & electric bill from April until December is at minus £860 🙂 Oh, almost forgot to mention, the Victron system can run Node Red, so you can do all sorts with it, I've written my own scheduling system, it also uploads directly to PV Output.

[@SpeakToTheGeekTech]

Yeah Victron are supposed to be among the best. But, not for the feint hearted as they’re a lot less consumer friendly :) great if you know what you’re doing though - I think given my knowledge now after being involved in this tech for a couple of years I might shortlist Victron if I were to start over again… but I’m now committed for many years to come!

[@TheRonskiman]

@@SpeakToTheGeekTech Yes it can be complicated, but I got my head around it so I'm sure you can. The biggest thing I like is that you can very easily control it, its very flexible as to what batteries you can connect etc. However I would do things differently now if I did it again, I would use prebuilt batteries rather than build my own. If interested Google "ronski solar and whole house back up"

[@JimGayes]

@@TheRonskiman +1 for Victron. We were lucky to find a local installer who has a Victron system in his own house.

[@mysmtpservices4818]

From.a.pwrson ppint of view. Make aire you know how.much eletrical you use per year Nd then bubble it for the battery. And also make sure you go for the large I inverter. As this will help in Saling the extra power to the grid

[@NelsonClick]

Conceptually, I now think of a home battery as a grid connected uninterruptable power supply (UPS) connected to whatever home system I predetermine I can't live without. In 2024 I could probably go a few hours without the fridge, washer/dryer, microwave and heating system. What I can't live without are the lights (led bulbs), enoughtl electrical to run a fan, the ability to charge my phone. I have a gas stove and the toilets work fine during a power outage.

[@SpeakToTheGeekTech]

Yup, we get a fair few power cuts so keeping a bit in reserve for those is crucial.

[@MikeGleesonazelectrics]

We have very few power cuts but my mg4 can supply about 3kW if nec and now also have a givenergy battery which could supply a further 3kw. So if both were fully charged it could theoretically provide 60kwh of power..

[@s0cialnetw0rk]

Octopus doesnt allow you to have octopus intelli go if you dont have ev. I have pv and batteries. Octopus says no to those have pv and batteries but ev. My argument is they are both battery charging.

[@SpeakToTheGeekTech]

Correct you must go for a different tariff designed for solar/battery owners such as Flux. Or get an EV if you can as they are trying to nudge you to do :)

[@tarbat]

I’m just going to wait until V2H and V2G are available. Might as well make use of the 60kWh battery in my car rather than spend thousands on a static battery.

[@SpeakToTheGeekTech]

If you always wait for the technology on the horizon you'll never do anything... my dad's still waiting for CDs to catch on.

[@terrymackenzie6784]

V2H and the cars to support it are still a long way out in the mean time you could be saving thousands of pounds a year and driving electric

[@terrymackenzie6784]

The problem with V2H and solar is when its sunny I drive to the beach in my EV I don't have 2 EVs at the moment

[@TheRonskiman]

@@terrymackenzie6784 My boss said I'd be better off with an electric car, until I asked him how much the company has to pay for it, my old car was bought and paid for years ago, so I just pay fuel, tax, insurance, and a bit for maintenance as I do that myself (mechanic). Far cheaper than paying hundreds a month for a similar electric car.

[@PaulLandregan]

You might be waiting a while

[@Damadchef]

The answer is yes... If you can afford it

[@SpeakToTheGeekTech]

Yup!

[@nightsupersteve]

Your wall mounted speakers are too close, so there is no real stereo effect. You got that simple task wrong, so why should people listen to you

[@SpeakToTheGeekTech]

Jeez dad I told you to stop watching my videos