Solar and battery help

kjenckes wrote:
Good Morning. I am hoping someone can provide a simple answer or 4 for me. I just read a post on the TC forum about flexible, light weight 100 watt solar panels and love the look of this, I have a Northstar 850SC pop up that this would go on. I have plenty of room over the bed end for these with out shadows from roof top stuff. I currently have 1 Interstate SRM-27 listed as 160 RC. (I will be adding a 2nd) I would prefer 31s but am not sure about the space available yet.

#1- Does the 160 RC on the battery mean 160 amps?

#2-50% discharge or 80amps (If #1 is yes) or 12.2 volts is the lowest I want to take this battery on a regular basis, correct? Therefore 2 would give me 160 amps?

#3- The listed optimum amps for this 100W panel is 5.7 amps with a max fuse of 10amps. Does this mean that 2 of these on the 20 amp controller is appropriate as the minimum? 30 safer? Could I run 3 on a 30?

#4- What is the rule of thumb for minimums watts per battery? I know sunlight hours and shade, etc affect all of this. I see some with 270 or more watts but no mention of how many batteries this supports.

My goal with all this is to get my wife out more with me. We both use CPAP (12v ). She is not as comfy with out some of the comforts of home as I am. We live in NH and the State Parks in NH and VT as well as the White Mt. and Green Mt. National Forest sites are almost entirely off grid.

I have learned a lot from this forum and want to thank every one for their posts.

1. Maybe 105 amp hours (not "amps" BTW)

2. Correct, except two 52s

3.a. Use the panel's Isc for your "expected amps" in full sun. The usual 100w panel has Isc about 6.3a

3.b. Size the controller to have a 20% margin over the total Isc. So two 100w in parallel gets you expected amps of 12.6 and 20% of that is 2.5 so plan for a controller at least 15a, so a 20amp is plenty.

4. There is no valid rule of thumb since there is no common scenario for each Rver. The weatherman runs the show anyway, so you get what you get on any given day. Just get as much solar as you can fit or can afford and be ready to run the generator if the weatherman is in a bad mood. But in general, for the likely usage of a truck camper, 200w is bags of solar most of the time unless you are in the woods where solar is fairly useless no matter how many watts you have.

5. An inverter will let you run 120v stuff off grid. DW will love having some 120. (as long as she knows not to run the batteries down too much)

6. Find the "Screwy 31" thread. Read it and weep. Don't get 31s