Questions about solar chargers

[BarryL]

Hey,
My boat is on a mooring. This year I bought new batteries (2 for the house and 1 for engine start) . I bought that exact unit from Defender. I just want something to keep the house bank charged up when I am away from the boat. It is fine for that. It is too small to run a fridge and other high energy loads.

Barry

 

[agprice22]

I think you need to build a power budget: amps/hour for each device to determine how many amp hours you will use at max. You can use that to determine how much you will discharge your batteries, keeping in mind that you get to use at most 50% of the rated amp hours of your battery. Then you know how much charge you need to restore through solar charging and how fast you need to restore it.
You can read Nigel Calder's book on boat electrical systems. He explains it well. Mainsail also does a great job.
Also, realize that the ratings on panels are maximum output. You will generally get at most 70% of that, so size your system accordingly. Many factors limit solar panel output: age and weather are 2 of them.