Diesel APU’s have a fundamental problem in handling small electrical loads.  They need to be turned on to satisfy even the smallest electrical demand.  Even with more sophisticated variable speed APU’s, the minimum operational fuel requirement is from .3 to .7 gallons per hour.    Fuel and energy is wasted; excess green house gas is released.

The most obvious example of this is in reefers.  Once the trailer is “pulled down” the refrigeration goes into maintenance mode.  The load maintains the cold and all that is needed is the fans to distribute the air.  The compressor may only be needed once an hour at most.  Yet, the diesel engine has to be fired up just to run the fans.

The beauty of solar energy is that it can run the fans without starting the diesel engine, saving up to .7 gallons of fuel per hour.  The energy production of solar is free, using the renewable source of sunlight.  The application is not limited to refrigeration fans.  It can be used to power lights and hotel loads.  Topping off liftgate batteries and pallet jacks between deliveries is an excellent application.