I wonder? (solar panels eventually a requirement?)

[Everest]

Rooves obviously

Roofs

I think it is a case of putting them everywhere.

everywhere that is practical - unfortunately there will be a lot of places that are not viable due to DNO network limitations for back-feeding of power.

So? could someone use solar panels to DC charge? Instead of AC.

Technically yes, but the complexity and cost of DC chargers would currently, IMHO, not be cost effective. @Coulomb is likely to know, but I suspect that some vehicles would have minimum voltage and current requirements for DC charging that would not be compatible with a small PV installation.

It's being so cheerful that keeps me going

 

[Bam Bam]

Roofs

Fair enough.

Technically yes, but the complexity and cost of DC chargers would currently, IMHO, not be cost effective. @Coulomb is likely to know, but I suspect that some vehicles would have minimum voltage and current requirements for DC charging that would not be compatible with a small PV installation.

Sigenergy have a DC charger now that connects straight to the battery.

Sigenergy Sigenstor EV DC Charging Module 25 kW 5m Cable CCS2

Part No: SIG-STOR-EVDC-25-5S2 EV Charging - EV Charger Sigenergy Sigenstor EV DC Charging Module 25 kW 5m Cable CCS2 Its unique 5-in-One modular design integrates Solar Inverter, EV DC Charger, Battery PCS, Battery Pack, and EMS into one intelligent home energy system. Simple, robust and...

www.powerland.co.uk

Costs more than an AC charger, though.

 

[Everest]

Costs more than an AC charger, though.

.. but - ouch!

 

[T1 Terry]

So? could someone use solar panels to DC charge? Instead of AC.

I'll tell you if it works or not when I set it up on my motorhome roof to DC charge the MG4 battery.
I figure as long as the open circuit solar voltage is 380vdc or less, it can't overcharge my LFP battery ..... it will probably be the slowest fast charger ever, but at least more efficient than changing from the high MPPT solar voltage down to DC battery voltage of say 48vdc nom. then back up to 230vac to feed into the CCS 2 charger and the MG4 change it back into the required DC voltage .... just need to understand how the MG4 knows it is going to be DC charged?

T1 Terry

 

[Coulomb]

@Coulomb is likely to know, but I suspect that some vehicles would have minimum voltage and current requirements for DC charging that would not be compatible with a small PV installation.

Actually, I don't have a feel for typical minimum values. There us no technical reason that DC charging can't work down at the few hundred watt level, other than "oops, we didn't think of that use case".

Obviously, the panel voltage has to exceed the car's battery voltage, although I would want to see a DC-DC converter used which can boost the voltage if needed. That adds cost and complexity.

The other issue is safety. You would be attaching cable rated at tens of amps to a vehicle battery with thousands of amps of fault current capability. So fault protection would be critical.

Yet another issue is compatibility with common solar inverters. The most common type puts high potentials on both PV wires with respect to earth. I don't think this would be legal for car charging, and would not be desirable even if legal. I wonder how the Sigenergy system deals with this.

It's nothing that can't be done, and an example has already been posted, but as an engineer the whole concept is a bit cringe worthy to me.

 

[Coulomb]

just need to understand how the MG4 knows it is going to be DC charged?

I assume you'd use a CCS plug for that, and send CAN bus messages over the control pilot (so-called power line communications, even though the control pilot wire isn't a power line). Just like a real DC rapid charger. Right there is a bunch of complexity and cost. Damien McGuire has figured out how to use used BMW electronics to ease the complexity. I can't see how you could safely avoid using a CCS plug though. The problem might be if you advertise to the car that you have 400V at 1.2A available, and the car laughs at that. Or you lie and say you have 10A but can't deliver it. The available current can change dynamically, as it must at a real DC rapid charger.

Have I put you off yet?

 

[john1000uk]

Actually, I don't have a feel for typical minimum values. There us no technical reason that DC charging can't work down at the few hundred watt level, other than "oops, we didn't think of that use case".

Obviously, the panel voltage has to exceed the car's battery voltage, although I would want to see a DC-DC converter used which can boost the voltage if needed. That adds cost and complexity.

The other issue is safety. You would be attaching cable rated at tens of amps to a vehicle battery with thousands of amps of fault current capability. So fault protection would be critical.

Yet another issue is compatibility with common solar inverters. The most common type puts high potentials on both PV wires with respect to earth. I don't think this would be legal for car charging, and would not be desirable even if legal. I wonder how the Sigenergy system deals with this.

It's nothing that can't be done, and an example has already been posted, but as an engineer the whole concept is a bit cringe worthy t

I'll tell you if it works or not when I set it up on my motorhome roof to DC charge the MG4 battery.
I figure as long as the open circuit solar voltage is 380vdc or less, it can't overcharge my LFP battery ..... it will probably be the slowest fast charger ever, but at least more efficient than changing from the high MPPT solar voltage down to DC battery voltage of say 48vdc nom. then back up to 230vac to feed into the CCS 2 charger and the MG4 change it back into the required DC voltage .... just need to understand how the MG4 knows it is going to be DC charged?

T1 Terry

Well I'd probably go this route, solar panels (the more the better) BLUETTI Elite 100 V2 Portable Power Station 1,024Wh 1,800W or as big as funds allowed and a Granny charger. Probably never get my money back but should work?

 

[T1 Terry]

I assume you'd use a CCS plug for that, and send CAN bus messages over the control pilot (so-called power line communications, even though the control pilot wire isn't a power line). Just like a real DC rapid charger. Right there is a bunch of complexity and cost. Damien McGuire has figured out how to use used BMW electronics to ease the complexity. I can't see how you could safely avoid using a CCS plug though. The problem might be if you advertise to the car that you have 400V at 1.2A available, and the car laughs at that. Or you lie and say you have 10A but can't deliver it. The available current can change dynamically, as it must at a real DC rapid charger.

Have I put you off yet?

No It will be 100% off grid stand alone, solar on the motorhome roof and fed into the MG4 51 battery so it can be used at night to power the rooftop rattler and all the other AC appliances ......
Maybe a small capacity battery to act as a capacitor to keep the current either on or off rather than varying between 13 amps and just a few amps. I can only fit 4.4kW of solar on the Winnie roof ..... without adding slide out "wings" each side when free camping to bring it up to 8.8kW so maybe 26 amps.

T1 Terry

First I need to find a CCS2 plug with the DC contacts as well, everyone I've seen advertised turns out to not exist when it actually comes to supplying it, and my money is refunded.

 

[john1000uk]

Good luck, looking forward to hearing about the finished project. Sounds like a good one for a YouTube video.

 

[Everest]

The other issue is safety. You would be attaching cable rated at tens of amps to a vehicle battery with thousands of amps of fault current capability. So fault protection would be critical.

... no problem... just call your 10A cable a "fuse" - fault protection sorted