Ok, let's analize this.
1. If you get a second battery, how old is the current one? You will want the batteries to be the same size and age so they will charge properly, if your current battery is very old you will want to get 2 matched batteries.
2. You need to determine how many watt hours you are using by checking your appliances etc watt rating. If you are running the fridge on propane you are only powering the circuitry for operation with the battery for monitoring, starting and stopping. If you have an inverter and running the fridge or anything else on 120 volt then you need to know the watt usage from that approach.
3. You will need enough solar to replace the battery usage each day in about a 5 hour window of good sun light. Formula = Battery amp hour rating X volts = watt hour available.
Example = 2 each 12 volt batteries rates 200 amp hours each = 400 Ah, never use more than 50% available Ah from your batteries you will ruin them and shorten their life span if you do.
200 Ah X 12 (volts) = 2400 watt hours available for use each day from the two fully charged batteries which means you would need for this example enough solar to produce more than 2400 watts in a 5 hour period (I say more than because you want the batteries to be fully charges and in a float stage at the end of each day).
My DW watches a lot of television when we are camping (me also in the evening) so we are running the tele and satelite equipment, when it is cold out and the kheater is in use it will use a lot of battery power, so I went a little heavy on my solar (at least for current use I will be adding more use as I determine how much my actual use is when camping.
288 watts solar
464 Ah worth of batteries.
At 50% battery use I can get 2,780 watt hours use but can only produce 1,440 watt hours in the 5 hour period at full efficiency on solar which is unreallistic to expect so let's say 1,000 watt hours is what I need to limit my use to if camping for say a week, just for two or three days we could stretch the usage some and be ok.
Ok so I got a little long winded but you see what I am getting at, if by your usage experience, going to 70 to 100 watts solar and 2 batteries covers your needs without using more than 50% available Ah by all means go for it along with your Generator to suppliment. So you need to do the math based on your needs.
Hope this helps and happy camping.
Dale & Terri, Lulu & Tiki (our Chihuahua's), New rescue puppy Prince - Pom/Pug mix.
2013 Tundra, Double Cab, 5.7, TRD Off-Road, 4X4, Full Tow Package
2013 Wildwood T26TBSS - Sold
2000 Gulf Stream Sun Voyager M-8357 MH, Ford Trident V10 Gasser, 35 foot.