Home battery system WITHOUT solar PV! Does it pay for itself?

Check out our latest video where we have installed this battery system just to charge from cheap overnight electricity. Does it pay to get a system like this?

Let us know your thoughts and questions in the comments!

[sevenacregreen]

Your calculations assume 100% efficiency for charge/discharge. What is the efficiency of the charge discharge cycle? Also what is the allowed capacity loss for the 10 year warranty? Should the capacity used for the calculation should be the average guaranteed capacity?

[AlphaShooters]

Great video! I'm currently trying to work out if adding a battery to our solar install will be worth the extra costs, but with the prices changing so much right now it's hard to make any accurate calculations. One thing most people seem to be missing out though is the lost interest from keeping £7500 (or whatever sum) in the bank, especially with some banks now offering around 5% interest. Of course if one needs to take out a loan then interest payments also need to be factored in instead. Hopefully with more home batteries coming to market we'll see the prices come down in the not so distant future, so I'm probably going to hold off on a battery for now, even though I'll miss out on the VAT saving from having it all installed at the same time which does suck a little!

[hyweljthomas]

I switched to Agile in early March and bought a 9.5 Givenergy battery - no solar. Costs: December: 26p per kWh (on Octopus Flexible), Mar/April: 11p per kWh. For me in winter, that's a saving of £115 per month. And in the last week, with all the negative charges, this dropped to 5p per kWh.
It's a no-brainer.

[LookatBowen]

An absolutely brilliant video! Thank you Sam. You've simply justified why I went with this exact solution. It makes total sense today, especially if the electricity tariffs continue to increase in the coming years. You've nailed it in the video though, really great presentation.

[allynonderdonk]

It seems to me that if you can reduce the charging current at night it will last longer. It seems you said there is a four hour low rate charge window that you charge in two hours. Batteries last longer if you charge them more slowly.

[BooBaddyBig]

If that battery is really fully charging and discharging every day, it's likely to have a horrible lifespan. Lithium ion batteries are normally only supposed to do 80-90% discharge to get full life. The other thing you haven't included is the charging and discharging efficiency. That's normally about 95% or so in each direction. So really you're having to put more than another kilowatt hour into the battery to charge that you don't get back.

[gavindyke]

Very tidy install mate. Nice to see a company taking pride in their work 👍.

[Chequr_Prostate]

Even though it is done a lot, I thought it was against the electrical regulations to clip cables to fencing and that the earth rod should be contained in a enclosure, with a warning label. If they lose the earth connection they could be in big trouble.

[odrlmc]

Great vid. Very few on this topic. What are charging/discharged losses with that inverter/battery combo?

[FiddlingwithmyWhistle]

Great video... but when are you taking new enquiries ?
would love to have a system like this

[stephenowens]

Those fences only last 5 years or so if untreated and maintained, not sure that earth wire being clipped to it is best option . Am I wrong ? .

[boomish]

By putting the battery on a floor isn’t it in danger of introducing damp or possible exposure to water ingress if the floor is washed? I’d prefer it sitting on a kind of rubber riser blocks, just an idea.

[fredflintstone]

If the system is fully discharging every day, is this considered to be one cycle of the battery? If so, after 10 years, the battery will have cycled from fully discharged to fully charged 3650 times (10 x 365). Assuming it still works after this time, it will probably be now working at 80% capacity, but will still be worth having assuming that the electronics (capacitors etc) have not given up the ghost.

[andylees]

Excellent vid, very useful and informative. £7.5k for 11kW battery is about £680/kw installed inc vat which is a great price/kW. As always oval’s installations are completed to the highest levels of professionalism, a joy to see such craftsmanship. Small matter on the blackboard you got the numbers the wrong way round 😉 bulb “ev” tariff is 10.1p/kWh 2-6am, 39.63p/kWh and standing charge goes up to 44.5p/day. Just need a smart meter. 20% vat on the £7500 is £1500!! 0% vat if solar and battery done at same time. Surely could have put a couple of panels up top for 1500 ready to expand and put that 1500 to better use?? Many thanks for your vid chaps👍

[jsouto]

Octupus go tariffs as of today would give even better payback. What surprises me is that you did not mention that if the customer had both solar and battery installed at the same time there would be no VAT to pay and there for a further big saving. Thanks for the content :)

[onthemove]

Nice video Sam. You emphasised that one assumption is the battery must deplete fully every day for these calculations. The other critical factor is the difference between peak and off peak costs. Octopus have just announced that new contracts will have a 12p off peak and ~40p peak rate on the GO tariff. There's no doubt in my mind that batteries have faster payback than solar PV, and if people are working to a restricted budget they should consider battery only.

[hoverbovver]

What is the required ohms for that earth rod? I had trouble getting it low enough for my EV charge point earth rod.

[philbrooke-little]

you need to get your divisions the right way round. You were saying and writing divide the annual Saving by the cost when what you were doing and what you should have said and written is divide the cost by the annual savings.

[twangi]

Great install, just what I’ve been thinking of doing as my roof space is complicated and has a lot of tree shade so solar is expensive and not very efficient. For the payback calculation shouldn’t you use the cheapest daytime rate available rather than comparing it to the daytime rate of the variable tariff? My understanding is that the daytime rate on a variable tariff is higher than a standard tariff, so comparing the saving between the night/day rates on a variable tariff is not a real saving, because you would choose a cheaper daytime tariff if you didn’t have a battery. Also any electricity you draw from the grid during daytime would be more expensive than the standard tariff so would have a negative impact on the saving calculation.

[jonnysegway]

Good idea, but be conservative with payback period. Add typical 20% to that payback period to account for battery storage/conversion losses; also after 5 years expect to have lost 20% storage capacity due to battery degradation.