[Paul Faure]

Hi,

Probably pretty complex engineering but using my excessive solar production for nightly home usage would be a great idea....
My Solar Edge setup can be hooked up to an external battery already (LG chem). Why not use an EV for this purpose?

Any thoughts?

 

[Yinzer]

It would require a good bit of engineering - the battery has internal contactors so the external connector is only energized when the key switch is on. What are the voltage requirements of the external battery? For charging, you can just feed solar-derived AC power to the car's on-board charger like normal charging. For taking the 340 to 390 volts DC out of the pack, you would have to splice onto the battery cables from the pack and leave the key switch on. The power train software may not allow you to do this though and open the conactors if it detects an unexplained drain.

 

[rfernatt]

There are companies working on this (e.g., Nissan) under the banner of Vehicle-2-Grid (V2G). Nissan has shown some working examples. There are of course some technical hurdles, standardizing communication among different OEMs, etc., but one of the big issues talked about is shortening the lifespan of that very expensive pack in your vehicle with excess charge/discharge cycles. Stationery energy storage (Powerwall, Powerpack, Megapack, etc.) use a different Lithium Ion chemistry (NMC vs NCA) that it is better suited to long term daily charge/discharge cycles. So, while it can be done, there are some pros/cons. I personally wouldn't mind having the option in an extended outage which would be infrequent unlike daily use. That ~75kWh pack in the LR Model 3 makes a 13.5kWh Powerwall look pretty small too! And, with 11.34kW of solar, I could certainly keep things running during a bad outage.

For greatest compatibility though, it should probably be AC coupled (like the v2 Powerwall) so that it is inverter agnostic and can work anywhere.