Buzz - Compressor fridges have only been around for a few years, so most of us don't have a lot of experience with them. Originally we did not buy roof panel because of parking in the shade or low sun in wintertime. Many of us bought portable panels or panels we use port-ably.
Many of us bought FWC or ATC to travel off road in the back country. So keeping the camper battery charged is a concern. The reason to install a roof mounted panel is charging the compressor refrigerator. The Waeco's /Dometic's draw around 4.5 amps. Just driving around with roof solar a 100 watt panel produces about 3.5-4 amps net per hour. Not enough to run the fridge and charge your battery but will slow down battery discharge process. Optimally 150-200 Watts will run and charge the battery because mounted flat you will lose about 40% of the out put. So a 150 watt panel will produce closer to 5-6 amps not the rated 8.68 amps.
The alternator is also charging the battery. Many of the owners have two batteries and 200 watts or more solar to keep the batteries fully charged.
Parking in the shade
In April we attended the FWC factory rally near Napa. We camped in a cloud 4 days with only a few hours of sun one of the days. We deployed our 60 watt portable. Weather was drizzly, rainy. Panel still ran the refer, the lights and maintained 12.9 volts while light out each day and we did not have to run the engine. Battery maintained 70% full. I think even in the shade roof solar would keep batteries 65-70%
You didn't say what "refer" you ordered. If it was the 3-way (AC/DC/propane) you don't need a roof panel as you will be running it either on propane off the grid or 110 volt when you have hookups. DC will be just used to maintain temperature while driving as it is dangerous to have an open flame (running propane) while driving.
Edited by RC Pilot Jim, 15 November 2015 - 12:58 AM.