aika1
Well-known member
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- Adrian
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It depends. Solar panels generate DC directly, but many installations use "microinverters" which are located at the solar panels and convert each panel's output to AC. In this type of installation no other inverter is needed, unless there is battery backup. See below why this is relevant.
The Ford CSS Pro doesn't do Level 3 charging, according to what I've read about it anyway, so it doesn't have to convert to DC in its normal usage mode. I think they must have some way of passing the DC, if it comes up the cable from the vehicle, to a separate inverter. I think this is why they are talking about having to have an inverter. I don't see why the CSS Pro would have a DC to AC inverter already built in. Up til now that hasn't been needed and it would be costly to have that feature if nobody was using it. Exactly how this hookup from the CSS to an inverter goes is not entirely clear.
This is needed when there is a battery in the system, especially a microinverter-based system, because as you say, batteries are DC devices. The microinverters at the solar panels generate AC which then must be converted by a central inverter back to DC to charge the battery, and when the battery is in use it must convert from DC to AC to power the house. This is how an "AC coupled" system like the Powerwall works, as I understand it anyway.
My SolarEdge inverter does not require a separate transfer switch. It has its own internal switch and disconnects from the grid when the grid is down so that it can safely put battery power onto the house circuits. Inverters not meant to use a battery have to "see" grid power in order to put energy onto their outputs, as a safety feature for electrical workers. To make such a system work when the grid is down, the system must be disconnected from the grid, and then a fake grid power signal has to be put on the wires to make the inverter think it is connected and can therefore switch on and generate AC.
some of that is semantics. The microinverters you speak of are still inverters, they're just stuck on your roof and aggregated in an AC Combiner box elsewhere.
I didn't know about the CSS Pro only doing Level 2, but I guess that makes sense. In that case, they may be relying on the Vehicles onboard charger, which functions as an inverter. So they'll just use the AC from the charger up to the car's charger/inverter unit.
Onboard Charger | Tesla
I wonder if the CSS Pro will just be the conduit to the house and use the vehicles onboard charger/inverter when needed. we'll have to wait and see.
The Solaredge system you have is slick. The Energy Hub acts as an Automatic Transfer Switch in the sense that it's tricking the inverter and optimizers to continue outputting by making it think it's still "grid-tied" but most people have the older systems that will need to have an external unit.
Regardless, I think folks will have to wait and see the CSS Pro and then work out the integration. Good luck, all!
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