Vertical PV panels

[SteamyTea]

11 minutes ago, CotswoldDoItUpper said:

Granny charger

Do you know the minimum charge rate your cars will take from that charger.  I think they are 10A chargers, but they may start charging at a lower rate.  You don't want to wait until your PV is producing 10A before the cars start to charge, though that would be the cheapest method i.e. no imports at all.

[ProDave]

1 hour ago, SteamyTea said:

Do you know the minimum charge rate your cars will take from that charger.  I think they are 10A chargers, but they may start charging at a lower rate.  You don't want to wait until your PV is producing 10A before the cars start to charge, though that would be the cheapest method i.e. no imports at all.

I believe Jeremy hacked learned the communication protocol and set up his car charger to charge at a rate matching surplus PV generation.

[SteamyTea]

1 hour ago, ProDave said:

I believe Jeremy hacked learned the communication protocol and set up his car charger to charge at a rate matching surplus PV generation.

Yes he did. Something to do with frequency and pulses. Or something.

 

[RobLe]

The standard J1772 socket on electric cars is usually used to home charge.  It’s got a protocol for what the pins do - mains AC is presented to the car, and a 1kHz squarewave is applied to a control pin which tells the car how much current it can draw.  The lowest current the protocol goes down to is 6A.  At 240V thats 1.4kW, it would be lower power at 110V.  It’s frustrating the protocol doesn’t go a lot lower, enabling slow PV car charging.  

[SteamyTea]

9 minutes ago, RobLe said:

 It’s frustrating the protocol doesn’t go a lot lower, enabling slow PV car charging.  

I suspect below the 6A limit there charging efficiency is impaired.

Be a bit like heating your water up from 10°C to 25°C.  Not a lot of use in reality if 25°C was all you can get.

Edited May 9, 2022 by SteamyTea

[RobLe]

You’re probably right.  But it seems shortsighted - that the protocol doesn’t include it, I’m confident that engineers could make it efficient at much lower current too.  Maybe it could be offered ad-hoc as an extra!  I’ve seen a few people try to direct charge EV cars from solar panels, and basically you can’t, because the protocols get in the way.  There’s a u-tube of a guy who does charge from PV off grid - he slowly direct charges 12V batteries, then uses an inverter to charge the car at a constant higher rate.  It works, but he has all that extra weight and inefficiency of extra batteries.

Edited May 9, 2022 by RobLe