solar charging an EV

[blitzracing]

Im starting from scratch with Solar panels to charge an EV. I have about 4kw available in good sunlight from the invertor, plus mains backup if needed. Now in simple terms if you put a solar cell on a battery as long as the battery voltage is lower than the cell, it will charge the battery, the current being dependent on the voltage difference. How do EV's draw current to charge? is It regulated so you will never draw more than the rated input, and does it always run at the maximum available input for the available voltage- ie 13 amps for 3.5kw or 43 amps for 10KW? Can you still charge an EV at less than 230 volts and the charge current drop accordingly? Im concerned if the solar invertor cant supply the request current due to lack of solar power, it will just shut down (If I dont have mains available) and that would seem a pity if my DC voltage from the panel is still higher than the cars battery.

[jjwilde]

You can buy chargers and home battery systems to handle all of this for you, perhaps look at the tesla power wall?

[Chris-S]

Are you proposing to AC or DC charge? The DC from the panels will vary wildly, so you are going to need some sort of regulation/inverting process there if you want to do that. If you propose using your inverter and AC charging, it’ll look after itself, balancing inputs from solar and grid as needed. If you want to maintain AC charging even during a grid power outage.....that’s an entirely different scenario.

FWIW, I’d go solar PV to inverter, grid connected as is typical, a battery system to taste (I have. PW2) and a Zappi charger that can monitor solar PV output and be managed to charge at variable rate to optimise solar PV use.

[blitzracing]

I would not contemplate trying to integrate the DC side of things onto the car batteries, so it will be an invertor. Luckily there is an invertor designed for EVs now that will do what I need

https://www.solaredge.com/uk/products/ev-charger#/

[Chris-S]

That’s perfect. Wish that had been available when I had solar PV put in. Have Solaredge kit and very happy with it.

[FlossyThePig]

Have a look at Nigel's EV videos on YouTube

https://www.youtube.com/watch?v=8Vy8yk_7CdU

[blueacid]

There's also the Zappi: https://myenergi.com/product/zappi/

It uses a couple of current-sensing clamps to work out how much power your PV is producing & how much everything else in your house is consuming.

You can put it in one of 3 modes for charging:
1) Just supply 32A (7kW) and don't care where it comes from
2) Charge the car only on PV, pausing charging when the solar panels don't produce enough power to permit charging after your house loads have been taken into account
3) Charge only on PV, but rather than pausing, switch to the slowest possible charge speed when insufficient PV power is available (so it'll still draw from the grid but only sparingly)

[blitzracing]

So- the invertor will supply 230 volts or nothing, so you cant reduce the voltage like you do on a DC battery to reduce the input current into a trickle. As I now understand it, all the invertor can do in low light conditions is hold the rising charge in capacitors until there is sufficient energy to provide a quick burst of 230 volts, then once the capacitors are depleted the out put voltage stops until the capacitor recharge and the cycle repeats. Does this sound correct?