pkulak wrote:Does it bother you that you're capturing power in DC, losing some of it through an expensive inverter, then loosing more again when your car's rectifier turns it right back into DC?
Not at all. In addition to what others have written, I will point out that the losses due to power conversion are already *very* low and will get lower in the future. The efficiency of microinverters is above 95% while the electrical efficiency of the LEAF's charger is also above 95%, so total electrical losses are less than 10%. In addition to the electrical losses, there is power wasted to run the cooling pumps. You could argue that this could be eliminated, but doesn't the LEAF run them during CHAdeMO anyway? (I wonder why?) Expect these efficiency numbers to get above 98% on both ends in the future, particularly for three-phase systems like they have in Europe. Small inverters at that efficiency level are already being deployed in three-phase PV generation systems.
pkulak wrote:Anyone ever think of just hooking some panels into a battery and using CHAdeMO exclusively to charge the car?
As QueenBee said, that would be a one-trick pony. Also, 240VAC is quite a bit safer than 400VDC.
Nekota wrote:But instead of efficiency at the local level consider efficiency at the grid system level. AC power is dynamic and generally peaks in the late afternoon and with a low demand in the early morning before sunrise. By contributing energy to the grid during high demand with solar PV and using AC energy to charge EV battery during low demand is actually helping the grid and the power company. As end use of electricity gets smarter and can turn itself on during low demand and off during high demand then more stability can be introduced into the AC power grid. Eventually, some feedback and control from the utility company or independent system operator (ISO) will also tell the PV system to produce less or more if the grid stability needs that. Currently the PV systems run at maximum output from the available solar flux so any type of grid control is likely years away. There is some degree of feedback operating now, each of the microinverters monitor the AC line and will not deliver power to the grid if the voltage is out of range or the AC frequency is out of range.
+1, and I would take this a bit farther: The best case is to never curtail renewable generation. If the on-board chargers in EVs can be replaced by four-quadrant power converters that can act as either a charger OR a generator, then we can have our EVs provide electricity to the grid during peak demand periods. As more and more PV and wind generation and more and more EV storage is added to the grid, we should eventually be able to curtail the more polluting generation systems rather than curtailing the PV.
Finally, I will point out that the motors used in the mass-produced EVs in the world are AC motors. Perhaps we should be using DC motors to eliminate a conversion there!