Should I bother with a battery? 14 February 2022 at 4:35PM edited 14 February 2022 at 4:37PM in Green & ethical MoneySaving 35 replies 1.4K views

michaels

1961Nick said:

For anyone on Octopus Go or Go Faster the case for battery storage has never been stronger.

The latest price is 7.5p/30p for Go & it should reflect the prevailing market as it isn't capped.

Charging for 4 hours per night on Go will yield a discharge of 11.35kWh. The cost of that will be about 9p/kWh after factoring in round trip losses. The savings are therefore 11.35 x 21p (30p - 9p) = £2.38/day... or £870 pa.

The capital cost of the equipment required is;

6 x US2000C @ £720ea = £4320 (or 4 x US3000C @ £1020 = £4080)
Sofar ME3000 = £700 (?)
Installation = £350

ROI = is just under 6 years for the US3000C (£5130/£870)... & that's without factoring in any of the solar output you harvest!

Of course all this is dependant on energy prices remaining at 30p/kWh after April 1st & Octopus keeping the huge differential between the on & off peak Go tariff.

Would you want 6 2.4kwh or only 5?  How many 95% dod cycles do they support?

Spies

Octopus need a tariff for people with a home storage battery, using the EV tariff isn't really an option if you don't have an EV!

That is truly when a battery will become a serious option. 

1961Nick

michaels said:

1961Nick said:

For anyone on Octopus Go or Go Faster the case for battery storage has never been stronger.

The latest price is 7.5p/30p for Go & it should reflect the prevailing market as it isn't capped.

Charging for 4 hours per night on Go will yield a discharge of 11.35kWh. The cost of that will be about 9p/kWh after factoring in round trip losses. The savings are therefore 11.35 x 21p (30p - 9p) = £2.38/day... or £870 pa.

The capital cost of the equipment required is;

6 x US2000C @ £720ea = £4320 (or 4 x US3000C @ £1020 = £4080)
Sofar ME3000 = £700 (?)
Installation = £350

ROI = is just under 6 years for the US3000C (£5130/£870)... & that's without factoring in any of the solar output you harvest!

Of course all this is dependant on energy prices remaining at 30p/kWh after April 1st & Octopus keeping the huge differential between the on & off peak Go tariff.

Would you want 6 2.4kwh or only 5?  How many 95% dod cycles do they support?

At 90% DOD, 5 x US2000 is 10.8kWh whereas 4 hours of Octopus Go is a potential 12kWh. The 6th battery would also allow some headroom for degradation - around 200w/pa.

I've increased my pack to 7 to allow room for solar storage in addition to grid charge & it's worked smoothly since December  with no intervention to adjust the daily charge percentage.

I've had my original 5 batteries just over 3 years & they're showing 836 cycles. That indicates a life (70% remaining capacity) of 16 years. That will improve now with 7 batteries as a grid charge takes them to just over 80% capacity. 

1961Nick

Spies said:

Octopus need a tariff for people with a home storage battery, using the EV tariff isn't really an option if you don't have an EV!

That is truly when a battery will become a serious option. 

Restricting Go & Go Faster to EV owners appears to be contrary to Octopus's active involvement with the load shifting trial that's about to take place.  The Go tariffs are currently the missing link between domestic battery storage & a very favourable ROI.

michaels

There is an edf 2 year fix that would work for those without gas.

1961Nick

michaels said:

There is an edf 2 year fix that would work for those without gas.

That looks pretty good if you can sign up without having an EV. A large enough storage system would virtually negate the need to buy any peak rate units as long as you're prepared to do a bit of sequencing around evening meal times.

Cottage_Economy

So, Redmile came out today with an electrician and tested everything. Verdict: mechanical damage. Something has hit one of the connections at the bottom of the inverter, damaging it and loosening it. It's been arcing and the damage irreparable. So it will be a new inverter. We store animal feed, straw, hay, logs and coal in there and can only think that when something was being delivered it was thrown in from the back of a van and hit the connections at the bottom of the inverter. No idea which delivery person it would have been so we just have to suck it up.

Given that we have to have a new inverter, Redmile has offered to quote us for both a straight replacement and also a hybrid inverter with batteries. So if we have to spend the money, it may be that we end up going for the battery option after all. 

It may be we also have to look at having doors put on the open end of the barn to prevent anyone throwing deliveries in there, or possibly adding a large wire cage around the inverter to protect it. 

1961Nick

“Mechanical damage” …. Insurance claim?

Cottage_Economy

1961Nick said:

“Mechanical damage” …. Insurance claim?

I have insurance for the inverter but unsurprisingly it doesn't cover accidental damage. It's possible I could claim on the house insurance but I chose the highest excess so I might only get £2-300 back. Then I might be looking at more expensive premiums in the future because I claimed.  

I'll wait and see how much the quotes are and then do some calculations and make a decision. We might be able to make it work. My concerns are down to us only being here another six years and not getting payback on batteries, but saying that we were going to be at the last place between 3-5 years and we ended up being there nearly 12 years. 

1961Nick

Cottage_Economy said:

1961Nick said:

“Mechanical damage” …. Insurance claim?

I have insurance for the inverter but unsurprisingly it doesn't cover accidental damage. It's possible I could claim on the house insurance but I chose the highest excess so I might only get £2-300 back. Then I might be looking at more expensive premiums in the future because I claimed.  

I'll wait and see how much the quotes are and then do some calculations and make a decision. We might be able to make it work. My concerns are down to us only being here another six years and not getting payback on batteries, but saying that we were going to be at the last place between 3-5 years and we ended up being there nearly 12 years. 

Batteries are very portable & can easily move home with you so that shouldn't be a worry.