I have the controller you are looking at. It came factory installed with a solar system on my TT. I am far from an expert on solar, but I can give you my experience. I have 2 group 27 batteries and have found that I can make it through a weekend using lights, fridge, 12V TV a little and water pump (quick showers). We can only dry camp in Fla. when it's cool enough--not often, but we had days last weekend. I have a generator, but don't usually use it over a weekend. I never would have purchased solar, but it was on the trailer I wanted so I took it. I am pleased that I have it now.