Originally Posted by Larry710
I am looking a little info here before I buy.
I have 2, 12v deep cycle batteries, only using lights and furnace. Colder nights the furnace uses a fair amount of battery resulting in running the generator a fair bit to recharge in the morning.
I'd like to get a solar panel to keep the batteries topped up so I don't have to run the generator as much.
will a 100w panel do the job?
Sunrise RV Kit - Wholesale Solar
A 100W solar panel will suffice if your only goal is to compensate for the Furnace, it will take all day to recover the batterie and might not entirely recover on cloudy day or if the exposure is not optimal (As in the panel is not aligned full south becasue they are on the top of the RV). Maybe 1/2 to 2/3 of a day on sunny day.
200W would be better and allow you to charge even on cloudy day when the panel are not as efficient.
When we need the furnace, it's usually not the middle of the summer! We need to account for the panel not being as efficient (less light).
Simply put, the 40K BTU furnace will run at about 4 amp hour (approx 45 watt/hour). The furnace doesn't run continuously, but if you used it continuously for about 10 hours your would use 10 X 45 Watt/hour = 450 watt hour. You need to put that back in the battery.
At full sun exposure a 100W panel will deliver approx 5amp hour. It will most probably run closer to 3-4 amps.