jwc99 wrote:
I was given 2 solar panels to use with my tt. They are Siemens SM55, 55 watt, 17.4 volt, and 3.15 amp each. I will use this setup 1 time a year when I make my Smokey Mountains trip, the only time I primitive camp. I have one 12 v 105 amp hour battery on the trailer. The only power we use in the trailer is for about 15 min of led lighting and each of us a quick shower at night. I would like to use the panels to help with the battery.
Any 10-15A controller will take care of panels. Xantrex/Schnaider C40 is capable of waay larger solar array, and is a nicely designed and fully adjustable. You might want to get (I would) their optional $20 temperature probe.
Your daily energy draw VS one battery is not clear, but a few days you won't have to worry about. Maybe - a few weeks, depending on how sunny it is and whether you have a DC circuit in your LP fridge.
Without fridge your panels will fully charge your battery on all but very dark days (think heavy rain or snow all day). Fridge is a big unknown. It may draw anywhere from 10 to 20 AH a day, unless it's a very old model with mechanical thermostat. With a typical 12-15 AH modern fridge and, say, 10 AH for all other loads, you need to harvest 25 AH from sun - possible with 2*3A panels on a sunny day. Again, with a typical 12-15 AH fridge on a less than perfect day you'll harvest 15 AH or less, and your battery will drop by 10-15 AH from where it was.
Edit - PS:
didn't notice that there was an uncertainty as to permanent or temporary panel mount. My numbers for solar harvest were for permanent roof mount: 6 Amp* 5 hours of full sun a day = 30 AH. I would do it permanent. With panels temporary leaned against the trailer you might get better results in off-season, as they will be tilted, but this is more pain every time. You'll enjoy your camping less then.
