Re: Solar Solution
Posted: Tue Nov 13, 2012 7:44 pm
While I wouldn't encourage anyone to run out an try it, it is entirely possible that the onboard charger will accept DC directly from a PV array. The input voltage of the onboard charger is reasonably wide (~100 to 250+?) and the first thing it is going to do is rectify AC to DC anyway, so why bother inverting power from a PV panel? It's not really necessary, but the intrepid among us could even implement a form of MPPT by monitoring the output with a microcontroller and adjusting the J1772 pilot signal for amperage to keep the panels at their optimal power output.AndyH wrote:A direct solar setup should be more efficient than a battery-based system anyway. Solar panels with a small MPPT board feeding a ~90% efficient inverter would provide electrons directly to the Leaf's charger. A battery-based system would require panels feeding a charge controller feeding a battery, which feeds an inverter and then the Leaf charger.
Sure, direct DC should be more efficient - but how many solar panels would one have to haul to hit 450-500VDC? Good luck with that on a portable system.
I was eyeing a bunch of Unisolar panels to roll up in the back of the LEAF for a mobile charge station. Turns out for ~4kW (down rate for ~3kW charging?) 28 144W panels would be an array of 18' x 36', weigh 450 lbs, and cost ~$5k. (I didn't even bother to figure out if they could be rolled small enough to fit reasonably). A potentially fragile and tedious, but less expensive and lighter weight approach would be to build a bunch of DIY PV panels from loose cells off ebay on light weight foldable/stackable backing. An array of 4kW would then be closer to $1500 in parts. A crystalline array would total about 400 square feet for 4kW instead of the 650sq ft above for amorphous.
Still, the charging time would be similar to the typical 3.3kW L2 rate, so you probably couldn't do more than one full charge per day (on a good solar day). It might at least be one way to leisurely and autonomously cross Nevada at a rate of 80-100 mi per day. I'm not sure how practical it is for other uses, given the size and setup hassle.