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Discussion Starter #1
If you want a decent battery for storing solar or to take advantage of Octopus grid tariffs etc, it costs quite a lot £££ to get decent storage. For example the Tesla power wall at approx 13kWh will set you back £11k.

However, when you look at EVs which have lost significant range the price drop is massive, we warn each other to avoid like the plague. Price wise I've seen a number of leafs (8bars) at 6k and less. We are talking about available storage of 13-15kWh here (for former 24kWh leaf for example).

It strikes me that these batteries have got higher value in a home storage context.

Is it really difficult to repurpose a battery?

Given that vehicle to grid trials are happening as we speak, I can't help but think you don't even have to do much. (In theory, if your property was big enough you could even keep the whole vehicle just to keep charger connected in if you couldn't be bothered to repackage in a compact case.
 

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Home storage make a lot more sense if you have solar panels so that you can use all you generate or perhaps avoid usage 4-7pm on one of those tariffs that is cheap overnight and expensive in the evening (I think octopus go is one).

Im not sure that v2g really makes much real money but I could be wrong. Maybe buy a damaged car from copart and just plug it into the v2g charger and leave it !

Cheers
 

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Discussion Starter #4

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My understanding is that V2G chargers start at around £7k, hence they're mostly just used in trials atm.
 

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One V2G/V2H question I've been pondering on; How much power is used\wasted keeping the car 'energised' and ready to charge\discharge at a seconds notice? It must add up to quite a lot 24*7*365.
 

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Plenty people have built DIY "power walls" from salvage EV packs. It does generally require some re-engineering of the pack though due to the various voltages etc. Most of the commonly available battery to grid inverters used in the DIY sphere run on voltages around 50v DC. Thus the 400v EV pack ends up needing stripped down to cell or module level and reconfigured into a ~50v assembly.

And yes, you could keep the whole car and just use a V2G charger, but i suspect cost wise it wouldnt make much sense. The car itself has lots of value that you'd be better off breaking it for parts, and the cost of a v2g unit means significantly more expense compared with buying a Sofar ME3000 or whatever.
 

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I don't doubt that this is the future for EV batteries at the end of their useful life for powering vehicles. There is a company near me which is already repurposing used EV batteries for commercial electricity storage. It probably makes more sense for these things to be done on an industrial scale for the best economy and to minimise the amount of peripheral equipment required per kWh of actual storage; but I imagine that domestic scale recycled EV batteries will become economically viable in the next 10 years.

I also think that Vehicle to Home and Vehicle to Grid will become fairly ubiquitous in the medium term if for no other reason than out of necessity to allow the grid to cope with the transition to EVs. The cost of the technology will definitely come down and it makes perfect sense to utilise those enormous batteries while they're sitting outside your house (or potentially wherever they are parked) which is what cars do for the vast majority of their lives. I know people worry about not having enough charge when they need the car, but it would be fairly trivial to design the system to allow people to set a minimum required state of charge by a target time to avoid any issues.
 

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...allow people to set a minimum required state of charge by a target time to avoid any issues.
Indeed the system Ovo use which is built by Indra renewable technologies does this, you say when you need the char charged by, and also a minimum charge that it should not go below when discharging to feed the grid.

I cant help thinking like the person above that it would work so much better on an industrial scale - plug the batteries only into racks in an industrial unit and use whatever capacity is left and then you can have hundreds of kw of power with thousands of kwh of storage. Building a chademo charger to use one car's available power seems quite wasteful, tho possibly an interesting trial to gain information for a better system in the future.

Cheers.
 

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Discussion Starter #10
Interestingly I've stumbled onto the Nissan xStorage whilst reading around this subject. With this home storage solution, they are apparently offering new batteries but also to purchase a used battery from a leaf. I can't quite find how much the ex-leaf are going for but a shortage in supply is hinted in a couple of articles I've come across.

 

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Sounds an interesting trial - I wonder if any forum users are on this trial?
I have a Powerwall and solar panels but am not yet on any EV related tariff. I must check but I thought my Powerwall was a lot less than £10k.
 

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It seems that reverse power is modestly expensive equipment, so even using the car as a home night time storage unit does nor seem realistic. In summer charge duringvthe day, power lights, fridge etc at night, but the schemes seem to be more commercial about v2g and getting the power companies business.
 
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