Review on EpRec Tracking Controller Regulator Display Tools & Equipment by Jim Ledbetter

I would say it's worth what you pay for it. At the moment I connected it to a small battery and controlled the inverter. I would not recommend using the output terminals to drive the inverter directly. I use the output to drive a relay that connects the inverter directly to the batteries. So when the battery gets too weak, the controller shuts down the inverter and saves the battery. By the way, the instructions are pretty bad.