Using the standard L1/L2 J1772 port to charge an EV is about 720 watts minimum with 120 volts and 6 amps minimum. This is fairly inefficient as the EV computer and cooling pumps will use about 200 to 300 watts as overhead. Tesla that can be controlled by the car might go a bit lower.
Did not know that. Is that 200-300W overhead whenever the EV is ON (just driving the V2L output, for example)?
The hard part is controlling the charge rate by what is available at the solar inverter on the fly. The EVSE pilot signal can be changed or stopped but will require a custom program to do this. Unless you are well over 1000 watts it may not be practical.
I have a total of over 3kW of AC-coupled Solar out of which I’m consuming an average of under 350W during daylight hours, so I’d be charging at at least 2kW.
I have no idea what EVSE is - do you have a link to explain?
If you can charge a separate battery controlled by the available source the system could work. Then as the battery gets full dump 1500 watts into the car until the battery is low. Good luck.
Charging my separate LiFePO4 with too much charge current is exactly the problem I’m trying to avoid.
But I think one solution I have is to use the LiFePO4 battery and GTIL inverter to close and gap.
Let’s say I turn in the 2kW charger once the AC-coupled solar output exceeds 1500W.
So worst-case, the EV charger needs another 500W and the house at need an average of 350W with a peak of as much as 600W (peak load when main fridge is running).
So I may need a worst-case additional 1100W peak or 850W average which can easily be provided by my two 1000W GTIL inverters from battery power.
850W of average power from my GTILs requires an average of 1063W from my LiFePO4 battery because GTIL efficiency is only ~80%.
My DC-coupled array is currently 1/4 the size of my AC-coupled array and I’m planning to double that to 1/2 when needed.
So 2kW out of the AC-coupled array should translate to 0.5-1kW of DC-coupled charge current being supplied to the LiFePO4 battery (meaning the worst-case power draw from the battery will be an average of as little as 63W with the increased array or much as 563W from my current DC-coupled array.
It’s not very efficient, but this should mean that on any normal-production day, I can charge the EV for 4-5 hours @ 2kW during the highest-production part of the day without importing and only exporting when AC-coupled solar power exceeds total load of EV charger + house load),
Otherwise yes a 6kw load will shut down a 3kw inverter.
Thanks, that’s the answer I was looking for.
The new NEM 3.0 decision has just been issued by the CPUC and it appears I’ll have more time to architect a solution to this problem than others have been lobbying for.
Legacy NEM1.0/2.0 customers are having their grandfathering period reduced from 20 years to 15 years, but that still gives me 10 more years on my current rate plan before the onerous terms of the successor tariff get imposed on me. The utilities were lobbying for an immediate transition of all legacy customers to the successor rate plan, so this decision gives me much more time (by which point there are hopefully even better solutions available).