Thanks to "Robert's" review I bought this unit and it works great with a solar system that provides the medium power needs of my fridge. I like the ability to set the voltages at which the device switches to AC power and the voltage at which it switches to battery. The documentation is very scarce and the seller's website will not help. Power cords are not included with the device and you need to connect them yourself. Robert's review explains how to make wires and how to set transmission voltages, not the seller! I would give the seller one star for the documentation. But the device works, so I give 4 stars.