Battery only? Anyone got such a system

Coveredinbees!!!!

I've been considering getting a home battery installed (without solar). We have an EV already and are on octopus energy (go) who offer this as an option. I check my recent bills and we are paying around £100 a month for electric, around £15 of which is standing charge. Octopus have a 10KWh for around £5500 which would power pretty much everything and possibly export during the day if that is a thing?

Has anyone gone for this option? With the rapidly rising cost of power I would think the payback time would improve. I can pay cash for the installation so won't need to pay for any finance.

QrizB

Has anyone gone for this option?

Yes, there are several folk on the forum who have batteries without solar.

Octopus have a 10KWh for around £5500

That seems rather expensive.

How about £4300 for 16kWh?

https://www.itstechnologies.uk/products/installed-solis-8-10kw-hybrid-plus-fogstar-energy-eco-16-1kwh?_pos=4&_sid=e82407aff&_ss=r&variant=58061330579837

Coveredinbees!!!!

Thanks for replying. Have you got a battery system? How is it working out for you?

QrizB

https://forums.moneysavingexpert.com/discussion/comment/82137950#Comment_82137950

I've got battery and solar. My battery is similar to the one in that ITS deal, although an older model.

I'm on Intelligent Octopus Go and I'm buying 95%+ of my electricity on the cheap off-peak rate. Back in January, for example, when there wasn't much sunshine for solar, we used 338kWh of electricity and 330kWh was on the off-peak rate.

Newbie_John

"rapidly growing" not sure about that

yes its been going up since March this year but before that its been going down since 2023, and if not the new war it would continue downwards, so as the battery investment is for 10 years plus, you cannot take this assumption, you can though say that you'd like to defend yourself from unexpected price jumps

£5500 for battery, out of all renewables they have shortest life span, so lets assume 10 years, your cost per year would be £550, your electricity cost is about £1000 a year - but if you deduct EV and anything that runs during your cheap period you may find yourself that you will only be able to save £550 a year meaning the battery will pay for itself but you wont save a penny

with these deals @qrizb posted you also get solar and that provides you more safety if the cheap overnight EV rate is ever stopped, with solar you have guaranteed 0p/kWh rate for apmost 20 years

lohr500

A lengthy reply, but I hope it helps :

We've had a 13.5kWh Tesla Powerwall 3 battery and gateway without solar since February last year.

Our 17 hour peak daytime consumption is +/- 12kWh, so the battery is well matched to support virtually all our peak load demand.

Our total annual consumption is very high at close to 20,00kWh (due to an electric AGA, water immersion heater, hot tub, washing machine,dishwasher, all of which run during the 7 hours off-peak).

So my requirement has always been to find the lowest possible rate to support the +/- 15,600kWh off-peak usage.Usually that means paying a premium for the peak period rate.

I've been on various tariffs in the past including the failed Tomato Energy TOU tariff, UW Economy 7 and now EDF GoElectric EV,.

The EDF GoElectric tariff gives 7 hours off-peak from 11pm to 6am.
I'm on an 18 month fix until Oct next year at 32.31p/5.48p.

At the time of switching we didn't have an EV, but we just bought one, so I expect my off-peak usage to increase by around 1750kWh from charging the car.

The battery cost £7800 to install and came with a 10 years parts and labour warranty. It also provides off-grid cover in the event of a power cut which is a bonus as we usually get 4 or 5 short term power cuts a year.

75% of the cost was covered by a 3 year 0% finance deal through Heatable which allowed me to keep more of my savings in a high interest account for longer.

It isn't an exact science as there are energy losses through the battery charge/discharge cycle, but if the battery is covering the 4,600kWh of peak load each year, then based on my current EDF rates, it saves me

(£0.3231 - £0.0548) * 4,400 = £1181 p.a.

With a £7800 cost the payback is 7800/1234 = 6.6 years.

Of course, the big unknown is what happens to the peak/off-peak electricity costs over the 6.6 year projected payback period.

Because the battery is closely matched to our daytime usage, we rarely have much surplus battery capacity at the end of each day, so I never bothered with export. (And I believe it is difficult to find suppliers who will provide an export tariff for battery only systems without solar)

As @QrizB mentions, battery storage is available for a lot less than the Tesla offering which makes the payback calculation more favourable.

Battery storage costs are falling and if I was starting out again with a battery storage solution I don't think I would choose Tesla. That being said, the 10 year Tesla parts and labour warranty does give peace of mind on such a large capital outlay. And the Powerwall is capable of sustaining an 11kW output. Some lower cost battery systems only come with a 3.6kW or 5kW inverter. It gives a bit more headroom for demand spikes if we have multiple high consumption electrical devices running simultaneously.
Also the Powerwall is solar ready and has a built in 3 string DC to AC solar inverter which would reduce the cost of any subsequent solar installation.


For a bit of fun and out of curiousity, I built my own 800 Watt DIY plug in solar system earlier this year to complement the system.
In total it cost me £370, including some specialist tub mounts to provide a drill free flat roof mounting solution.

From 1st May to 31st August it generated 389kWh. Generation will fall over the autumn/winter/spring.
The PVGIS solar tool estimates I should get 680kWh p.a.
Everything generated will either have reduced the demand on the battery or put a small amount of charge back into the battery.

Without trying to get any export on that 680kWh (all of which would be surplus to the battery capacity) then in simple terms I guess it is saving me around 680 x £0548 = £37.26 p.a. In reality it will be more due to the energy losses associated with charging/discharging the battery.

SVaz

I’ve just started looking, British Gas do one at what looks like a reasonable cost BUT, you can’t use it as a back up system if the power goes down so I’m not exactly sure the point of it is.
Surely the whole point, along with cheaper power, is contingency for if the power goes out?

I’m going for a large 3kwh power station plus solar panel instead, half the cost and you can fill it with cheap electric, solar or even off your car.

QrizB

British Gas do one at what looks like a reasonable cost BUT, you can’t use it as a back up system if the power goes down

I don't know what system BG are offering but almost all of them include an EPS (Emergency Power Supply) function. This does however require a certain amount of additional wiring.

What makes you think the BG one doesn't?

UPS function (Uninterruptible Power Supply, where the battery cuts in withun 1/50 second) is less common.

I’m going for a large 3kwh power station plus solar panel instead, half the cost

Likely to result in much smaller savings, though.

SVaz

The blurb states that you cannot use it as backup power

“Can my home battery provide backup power?

No, we don’t currently offer any backup power functionality with our home battery. It’s unlikely you’ll need backup power though: according to the latest Ofgem report, the average household in the UK experiences fewer than one outage per year, and loses electricity for around 36 minutes in total.The numbers are falling, too: the average UK home experiences 38% fewer power cuts now than it did in 2010.”

As I stated : Completely pointless

QrizB

The blurb states that you cannot use it as backup power

BGs battery looks to be a collaboration with Sunsave.

Sunsave are offering Hinen B5000-series batteries.

Hinen's own site shows that the inverter in their B5000 batteries has an EPS connection. BG might not be connecting it, but it's there.

As I stated : Completely pointless

That's only your opinion.

Even without EPS enabled, a home battery can save you 10p/kWh on your electricity. Hardly "pointless" on a moneysaving site like MSE.

SVaz

I’d imagine that for 99% of people, having back up power is the main reason for wanting a home battery, I hadn’t even considered it could work out cheaper, which it will only do some years down the line once you’ve passed the break even point.