I ran a test on power consumption of the Vitrifrigo
and measured the alternator's capacity for recharging.
Then I looked at solar PV capabilities today to decide
if solar was right for the way I camp.  This information
might be of use to others, so I put it up:

http://jones.colorado.edu/VW/Vitrifrigo/VitrifrigoBatteryTest.txt

http://jones.colorado.edu/VW/ChargingAuxBatteries.txt

One other factoid:  a Vitri tech specialist pointed out that
the fridge needs certain power.  Power = V x A.  If the
wiring to the fridge limits V, then A will be higher than
their spec.  Yes, I confirmed this with my initial wiring.  ;-)

Richard