Solar Roast Truck Power System

I built this system to use three panels and six batteries from our decomissioned Helios 4 Solar Roaster.  It also makes use of the Xantrex inverter charger that was already in the truck.  I added a Xantrex charge controller, and installed disconnects and appropriate fuses on everything.

Six Rolls batteries drop into a compartment I opened up below the service counter.  I lined the floor with a poly liner and silicone caulk.  The compartment has a vent from the inside at one end.  I installed a 13 watt brushless AC fan at the other end to pull the hydrogen out.  I simply runs the whole time the inverter is on. 

The power compartment below floor level.  It has a gasketed door.  I removed the old batteries, and cleaned it out with a wire brush before painting the inside with metal primer.  I built a base and back out of painted 1/2" plywood, and supported it on standoffs about an inch above the box floor.  I put a couple 1/4 inch holes in the bottom of the box to help with drainage, should water get in.  There is one exhaust vent in the back of the box behind the board that supports the disconnects.  I placed an intake fan at the front of the box.  It draws air in through a baffle, which directs air from the outside forward and then up.  This should prevent water splash from entering the compartment, while still allowing good airflow to cool all this stuff. 

The PV pan-tilt control center (and fire-extinguisher).  The flex conduit from the top contains the feed from the PV, and the thick poly conduit from the top of the box contains the runs to the tracking motors and limit switches, sun position sensor, etc.

It started very neat and orderly, and became progressively less-tidy as the feeds from above entered the box!  The two reversible AC motors are controlled by the 4 relays at the bottom.  I built the control system around an AutomationDirect Koyo Click logic controller module, and programmed it with ladder logic.  The software is very basic right now, but will get an upgrade next month, with some better control limits and an automated panel-stow procedure.  I will be adding the solar tracking module shortly after that, once it has all been tested. 

The battery vent.