I use this controller along with a 30 watt solar panel to keep my engine battery charged while my RV is at summer camp. So far (after a month of use) the panel and controller are working great. I was skeptical about this device given the low price, but to my surprise it works just as well as the more expensive models. It might not last as long, but for the price - who cares? I'll just order another one when this one comes out. I highly recommend it.