You can do a lot of calculating or ask someone who lived several years on solar. It also helps that I have a E-meter that accurately measures the amp hours leaving the battery and returning.
I have a 415 watt solar system. I bought a MPPT controller back when a 50 amp Solarboost 50 cost around $375. Now you can buy a 20 amp PWM controller for as little as $13 and it will have a relay that comes on at dusk, shuts off at dawn or a preset number of hours after dusk. I bought two, and they are still working.
Your RV will consume about 35 amp hours daily just to run the refrigerator, CO meter and propane detector. In addition, you need something for the lights, furnace, and any 'optional things'. This can include a CPAP that might consume 50 - 75 AH nightly, or a lot of TV usage. I had a Direct TV receiver and 19" tube type TV, and could use 120 AH in one night. Then recharge about 110 AH during a winter day.
After a few days, I normally was done with the camping trip, and it would fully charge the day after I got home.
So I would recommend a pair of 140 watt 12 volt panels from this place. ABout $229 each.
SunElec.comDiscount solar probably can get very close to the same price. Use a open mind. Don't go in and say you must match the prices quoted online, but also don't overpay and write a blank check either. You just want a similar price, or keep shopping all over town.
I went shopping there in 2007 and went to a couple of places, buying 4 each 100 watt panels, a 1,500 watt inverter and a couple of extra 12 volt AGM batteries for a guy who wanted me to install it. WE went to a couple of places. WE bought at the lower priced place.
Good luck,
Fred.
