Using an EV as a battery in a solar power system
Discussion
Does anyone have any experience of using an EV to replace fixed batteries in a solar power system? My pipe dream is to use a Tesla Model S as a replacement for fixed batteries in a theoretical PV setup of say 22 panels. Can a Model S be doctored to deliver power back to the house after harvesting energy from the panels / cheap rate grid electricity?
muchacho said:
Does anyone have any experience of using an EV to replace fixed batteries in a solar power system? My pipe dream is to use a Tesla Model S as a replacement for fixed batteries in a theoretical PV setup of say 22 panels. Can a Model S be doctored to deliver power back to the house after harvesting energy from the panels / cheap rate grid electricity?
No, it would need hardware and software upgrading to provide V2G (vehicle to grid) or V2H (home)I think the Nissan Leaf supports it, with a specific charger https://www.indra.co.uk/v2h/ for trials only.
People used to get excited about this, back when Vauxhall EVs were cheaper per kWh than Tesla power walls.
I don't think there is much point now, you can buy brand new LFP batteries for £200 per kWh or less.
Obviously you need some conversion and control hardware, the costs soon rack up like with any other project.
I don't personally know anyone who charges an EV from solar except incidentally? Sorry if that's a bit of a tangent!
I know lots of people with solar and battereies and inverters on boats and camper vans, there is tons of info on the web, but things change over time and many people have been doing this for 15+ years now.
Everybody has their own set of goals and circumstances, along with beliefs about future electricity prices and the like!
So you can't really assume other people's favoured solutions are right for you.
A few people have found a bit of V2L capability has been useful in powercuts, all good stuff, but IMHO not in itself a justification for spending lots on an EV.
I don't think there is much point now, you can buy brand new LFP batteries for £200 per kWh or less.
Obviously you need some conversion and control hardware, the costs soon rack up like with any other project.
I don't personally know anyone who charges an EV from solar except incidentally? Sorry if that's a bit of a tangent!
I know lots of people with solar and battereies and inverters on boats and camper vans, there is tons of info on the web, but things change over time and many people have been doing this for 15+ years now.
Everybody has their own set of goals and circumstances, along with beliefs about future electricity prices and the like!
So you can't really assume other people's favoured solutions are right for you.
A few people have found a bit of V2L capability has been useful in powercuts, all good stuff, but IMHO not in itself a justification for spending lots on an EV.
Thread resurrection now that I know I am getting the car (I am feeding from the cheaper end of the Model S crop)! Thank you for your thoughts so far. I did put the idea to the potential contractor for the solar project when he came round to check the lie of the land and he was really enthusiastic. In fact for a 42kWp proposal he did not include any fixed batteries as he believes that they are not yet cost-efficient but when I mentioned the car he said that it made sense as all of the charging and battery management kit was already baked into the car. With the added bonus that this battery can be driven around. Assuming that I can get the car doctored to do V2H what am I missing? In any event I am taking on a 2017 90D this coming week.
muchacho said:
Assuming that I can get the car doctored to do V2H what am I missing? In any event I am taking on a 2017 90D this coming week.
Are you sure you can do the "doctoring" with a 2017 Model S? V2H / v2g is a big "dream", but with the price of batteries, people generally end up having big cheap batteries attached to the house, rather than try to hack around Tesla's controls to use/abuse the (rather more) expensive battery inside a Tesla to save ~10-20p per unit in power arbitrage.I've heard of some gadgets for Tesla, but I'm sure they're not approved, and I don't know if they are really up to UK spec for power generation. Could be fascinating to hear more.
muchacho said:
Thread resurrection now that I know I am getting the car (I am feeding from the cheaper end of the Model S crop)! Thank you for your thoughts so far. I did put the idea to the potential contractor for the solar project when he came round to check the lie of the land and he was really enthusiastic. In fact for a 42kWp proposal he did not include any fixed batteries as he believes that they are not yet cost-efficient but when I mentioned the car he said that it made sense as all of the charging and battery management kit was already baked into the car. With the added bonus that this battery can be driven around. Assuming that I can get the car doctored to do V2H what am I missing? In any event I am taking on a 2017 90D this coming week.
whether a battery is 'cost efficient' depends a lot on how you look at things.Do you place much value on having power during power cuts?
What's your opinion on the future of tariff-surfing?
How much solar will you have compared to your summer/winter daily demand?
A battery can be fairly cheap for some configurations.
You might find when push comes to shove, there's a value to having power at home when the car isn't there?
Personally I think a big solar array and enough battery capacity to be almost off-grid 80% of the year looks like a valid way forwards for some people.
EVs complicate the picture IMHO, people's use patterns vary a lot.
Just be mindful the chemistry in Model S/X packs are some of the most 'Unstable' interms of thermal run-away. The BMS on a S/X never really turns off due to the need to constantly ensure no cells are about to go pop. The battery chemistry Tesla use in PowerWalls are entirely different, meet very strict domestic installation safety checks.
No one will stop you messing around with packs, but thermal run away is a very real risk. The PowerWall has been around now for almost a decade and I don't think I've ever seen a single report of thermal runaway, Tesla even set one on fire and it didn't combust. People who mod/mess around with S/X battery packs is a different story, fire due to thermal run away is an occupational risk.....
https://youtu.be/of01p0Q-yUM?si=CnxyMs8OokncgxJb
https://insideevs.com/news/541361/gruber-fire-dest...
No one will stop you messing around with packs, but thermal run away is a very real risk. The PowerWall has been around now for almost a decade and I don't think I've ever seen a single report of thermal runaway, Tesla even set one on fire and it didn't combust. People who mod/mess around with S/X battery packs is a different story, fire due to thermal run away is an occupational risk.....
https://youtu.be/of01p0Q-yUM?si=CnxyMs8OokncgxJb
https://insideevs.com/news/541361/gruber-fire-dest...
Edited by gangzoom on Monday 23 February 06:43
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