On-grid domestic battery storage

orrery wrote: »

Oh, me too. I think that I'd like to see 3kW discharge though - with washing machines and dishwashers and kettles taking 2.2kW and a level of background for the house, I'd say that was a minimum.


Similarly, the graphs (which were very helpful) we have seen recently indicate the need for a charge level of 3kW too - again that for me (with a 4kWp PV system), less the background consumption, would seem the minimum.


Further, with 3kW charge rate and economy 7, the ideal battery capacity would seem to be at least 21kWh minimum - roughly the same figure would be indicated for sinking (almost) a full day's PV generation.


Sounds expensive.

When I first started looking at Solar and batteries I thought a massive battery would be a great idea. However the reality is that if you are going to charge it from solar you will end up with far more energy stored than you can use in summer and unable to generate enough to fill the battery anywhere near your needs in winter.

I would suggest you base your battery around what spare generation you have in February, March, September and October. I have a 7.8kwp and am nowhere near filling the battery on this so far gloomy day.

I can see that I will be charging it from Economy7 in the winter.

JKenH wrote: »

I don t actually know exactly how much my battery cost as it was part of a system. If someone can tell me how much a 7.8 kw system (26 x 300w mono panels) on two roofs with 2 inverters and IBoost should cost then I can work out the true cost of the battery.

From what others have said they have paid for a similar size solar PV system without batteries, I would estimate between £8-10k.

ASavvyBuyer wrote: »

I have started researching EV's & PHEV's for when we change our clean diesel car in the next couple of years. Had a look at a few yesterday to assess size, range, etc.

In one of the reviews I found for the new Nissan Leaf it mentions: "Other green features include vehicle-to-grid (V2G) connectivity for all new Leafs, which opens up the possibility of using the Nissan as a portable energy storage unit for peak demand, and/or selling power back to the grid."



Also found this when looking up info for the new Nissan Leaf:

"Vehicle-to-Grid (V2G) technology combines two-way charging allowing electric vehicles to be fully integrated into the electricity grid. It helps improve the capability to handle non-programmable renewable energy flows, making renewable sources even more widely integrated and affordable. The system works by allowing Nissan EV owners to connect to the grid to play an active role in grid services, while providing the opportunity for an alternate source of income. Once scaled up, the V2G technology will be a game-changer for owners of Nissan electric vehicles as they become active participants in the energy market."

For those that already have a new Nissan Leaf, is V2G/V2H already available, or have you been told when it will be available to use in the UK?

Hi ASB, the V2G aspect and range of the new Leaf were the two main reasons we went for one. Unfortunately the V2G aspect is not yet available although OVO are currently seeking participants to take part in a trial for this. I believe it includes a free installation, those already with solar can be included although you may need to be an OVO customer. They also require your post code so it may just be a regional trial! Maybe worth checking out!
https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger
Personally I merely require V2H as opposed to V2G so not sure if I wish expose my new car to it, although I understand it is being conducted with Nissans approval regarding battery lifetime and warranty.

Hi Savvy
On a side note a smets2 smart meter will help as this does import as well as export in real time.

Coastalwatch wrote: »

Hi ASB, the V2G aspect and range of the new Leaf were the two main reasons we went for one. Unfortunately the V2G aspect is not yet available although OVO are currently seeking participants to take part in a trial for this. I believe it includes a free installation, those already with solar can be included although you may need to be an OVO customer. They also require your post code so it may just be a regional trial! Maybe worth checking out!
https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger
Personally I merely require V2H as opposed to V2G so not sure if I wish expose my new car to it, although I understand it is being conducted with Nissans approval regarding battery lifetime and warranty.

Thanks for the link; very interesting. However, same as you, I would only really be interested in V2H so that I had some control over how much of the car storage was being used. Mainly to cover evening and overnight low use, and to stop importing when a cloud comes across when the washing machine is on.

Also, I may have misunderstood the figures, but it appears that OVO would charge you at normal rate to charge up the car, but only pay you about half of that when they export power from your car battery (and as Dave says, shortening the life of the battery).