Battery without solar panels

gillyann01

Thinking of getting a battery to help with energy bills but not having solar panels. Has anyone else considered this?

Ectophile

It's an option. You would need to sign up for a cheap overnight electricity tariff. Then charge the batteries at night and use them during the day.

Do the sums to see whether or not it's financially viable. The overnight rate has to be cheap enough, or it may take a very long time to pay back the cost of the batteries. Make sure to allow for a small loss of maybe 20% when charging and discharging the batteries.

debitcardmayhem

Have a look here too https://forums.moneysavingexpert.com/discussion/6673549/octopus-announces-the-nook-plug-in-battery#latest

QrizB

Welcome to the forum!

Thinking of getting a battery to help with energy bills but not having solar panels. Has anyone else considered this?

There are one or two people currently active on the forum who have done this. Yes it works provided you have the right battery and the right electricity tariff.

Hopefully one of those folk will be along shortly to share their experiences.

Swipe

I've just crunched some numbers and, based on my annual daytime usage (3kWh per day - at my rates of 36.6p day and 6.9p night), I would ony save around £300 a year to offset against the cost of the battery.

QrizB

I would ony save around £300 a year to offset against the cost of the battery.

With a battery of that size currently costing £1300 or so (link), it'd pay for itself in four to five years.

(At the moment you'll need to have it installed by an electrician, which adds cost. That battery is designed as a plug-in unit and Government is supposedly looking to legalise plug-in batteries eventually).

Swipe

https://forums.moneysavingexpert.com/discussion/comment/82094918#Comment_82094918

Would that battery still be of any use after 5 years though?

QrizB

https://forums.moneysavingexpert.com/discussion/comment/82094939#Comment_82094939

The manufacturer of that particular one offers a 10-year guarantee on it, so I'd expect so. And they've recently announced a refreshed range with a 15-year guarantee.

LFP cells are commonly rated for 6-8000 cycles, which is 20 years of one cycle per day.

Swipe

Thanks. definitey worth considering then once they allow plug in via a plug socket

lohr500

Battery only with no solar is working well for us.
We had a 13.5kWh Tesla Powerwall battery installed 18 months ago.

We do have a slightly unusual situation though with an AGA storage cooker which heats up overnight on off-peak electricity. Typically it uses around 35kWh each night. Say 12,7500 Wh per annum.
We also use the off-peak rate to heat up the hot water.
And there is the base overnight house demand.

So getting the best possible off-peak rate has always been key for us. Most nights, the AGA does need close to 7 hours to reheat as it was designed around the use of Economy 7 tariffs.

In total, on a 7 hour off-peak tariff we used around 14,000kWh off-peak, 7200kWh peak.

With the exception of when we were with Tomato Energy before they went bust, most tariffs offering a traditional low off-peak period came with a peak rate penalty. We've been on several different tariffs in the past, jumping from supplier to supplier to chase the lowest off peak rate!!

On on our current EDF EV tariff, we are paying 5.48p for 7 hours off-peak and 32.31p for peak. The SVT price in our region is 26.11p.

Looking at the numbers in a fairly basic way :

Without the battery we would be paying (14,000 x 0.0548) + (7200x 0.3231) = £3094.
On SVT (21200 x .2611) = £5535. So being on a two rate tarrif makes a big difference.

With the battery (which covers 99.9% + of our peak daily demand) and assuming an 8% loss from the charge/discharge energy losses our annual cost is (14,000 x 0.0548) + (7200 x 0.0548 x 1.08) = £1193.

Havng the battery therefore saves £3094-£1193 = £1901 per annum.

The Tesla battery came with a 10 year parts and labour warranty and cost £7800 including installation and all the necessary DNO applications.75% of the battery cost was financeable over 3 years at 0% interest which softened the capital outlay impact!

Based on the current annual saving of £1901, the payback is around 4 years.

in reality the payback will be a bit longer because I haven't built in the slightly higher daily standing charge for the EV tariff we are on and I have perhaps been conservative with the 8% power loss factor from the battery charge/discharge cycle.

Also, the biggest unknown is what happens to the peak off-peak electricity cost differential over the payback period.

Battery storage prices are falling which will make the payback calculation more favourable.

In addition there are many time of use tariffs out there (both with fixed periods and intelligent variable periods) that make the calculation more difficult. In our case the AGA really needs a stable fixed window to reheat the core, so a traditional Economy 7 or fixed off-peak EV type tarrif work best for us.

It really comes down to you understanding your usage pattern and looking at what capacity battery you would need to cover the peak period on any split rate tariff.

QrizB

Looks like @gillyann01 's thread has been moved to Green & Ethical. Hope they can still find it!