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Discussion Starter #1
I don't know if GM reads the other threads, so I just want to post this suggestion here to be sure GM sees it.

Very many Volt owners will want to use solar panels to charge the battery. Besides an AC input, the Volt should have a DC input so that a solar panel array can charge the battery directly. This would make it unnecessary to have an inverter convert the direct current from the solar panels to 120 VAC, which would incur the expense of the inverter and energy losses in the conversion from DC to AC and back to DC. Better to leave the AC step out and just go DC to DC.
 

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Quite a few AC/DC converters just work fine with a DC input. It is quite possible that it will just work.
But the eletricity is still flowing through the power components. I don't know enough about rectifiers, but I guess as long as DC flows through with very little loss this will suffice. Unfortunately, I don't think this is the case for the various diodes, filters, and capacitors used.
 

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It seems like it'd be relatively trvial for an aftermarket charge controller that takes standard 24V/48V DC and charges the batteries. I agree it'd be better overall for consumers who have solar

...but...

making it factory installed will add to the cost, increase R&D, and have another manufacturers support point of failure. Id love it as an after-market or dealer option though.
 

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I don't know if GM reads the other threads, so I just want to post this suggestion here to be sure GM sees it.

Very many Volt owners will want to use solar panels to charge the battery. Besides an AC input, the Volt should have a DC input so that a solar panel array can charge the battery directly.

You would need to size the solar array so that it would produce a voltage higher than that of the cars battery pack in order to charge it. So, if the car had a 300 Volt battery, the solar array must produce a voltage at least equal to or higher than 300 volts. You can't step up a DC voltage unless it's run through some form of oscillation.

This would make it unnecessary to have an inverter convert the direct current from the solar panels to 120 VAC, which would incur the expense of the inverter and energy losses in the conversion from DC to AC and back to DC. Better to leave the AC step out and just go DC to DC.
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I don't know enough about rectifiers, but I guess as long as DC flows through with very little loss this will suffice. Unfortunately, I don't think this is the case for the various diodes, filters, and capacitors used.
The battery charger circuit probably is going to have a PFC front end. That means a boost converter that has an output higher than the peak of the line voltage. Now, if you substitute a DC input, then the boost converter just runs at whatever duty cycle is necessary to reach the same output as when running on AC input. If the DC input is on the high end, then the efficiency will be higher than on AC. Anyway, I think that connecting a DC voltage on the plug will just work anywhere from ~100V to ~375V, but efficiency will be higher toward the upper end of the voltage range.
 

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Discussion Starter #8
LyleL wrote:
"You would need to size the solar array so that it would produce a voltage higher than that of the cars battery pack in order to charge it. So, if the car had a 300 Volt battery, the solar array must produce a voltage at least equal to or higher than 300 volts. You can't step up a DC voltage unless it's run through some form of oscillation."

I had no idea the battery voltage would be that high. I assumed something like 48, 72, or possibly 96 volts DC. It's not unreasonable to get that kind of voltage out of a series solar array. But 300 volts DC is a different animal, a very dangerous animal if someone tinkering with the battery completes a circuit with their body between positive and negative.
 

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LyleL wrote:
"You would need to size the solar array so that it would produce a voltage higher than that of the cars battery pack in order to charge it. So, if the car had a 300 Volt battery, the solar array must produce a voltage at least equal to or higher than 300 volts. You can't step up a DC voltage unless it's run through some form of oscillation."
The charger will have Power-Factor-Correction - I think it is mandated. This means that there is a switching converter between the AC input and the battery. This converter (usually) doesn't care whether it is running from 60Hz or DC, as long as the DC is below ~375V.
 
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