The Ecoworthy was moved to the back window since that seemed to get more sunlight in the morning. 

Current logging would find the optimum position, but you've got a shunt resistor, an op-amp, feedback resistors, an ADC.  All the resistors have to be schmick to withstand the temperature changes in a car.  Another idea was making a timelapse movie, but the camera needs to withstand high temperatures.  

The battery was never recharged from manes voltage after going to the Ecoworthy, so the results with the Ecoworthy were never fully known.  It definitely wasn't dead.  The car seemed to start as fast as a fully charged battery, after months between drives.  

After much debate, the optimum way to stand up the panel was viewed as a pool noodle.  The front has the instrument cluster to prop it against.  The back has the seats to prop it against.  The front passenger side would be problematic.  The lion kingdom had some 20 year old pipe insulation which could be bundled.  It's unknown how it withstands high temperatures.