Save your money. They cause more damage then they are worth.... just button it up tight and twice a year go up on the roof and check very carefully (hands and knees) for any cracks in the lap sealant. (you should do that anyway)
2004 Chev Silverado Duramax optioned past the max. 2009 Jayco Eagle 308 RLS 765 watts of solar, 6-6 volt batteries (696 amp hour), 2000 watt (4000 surge) whole house inverter.
140 days boondocking in 2016
211/2015, 196/14, 247/13, 193/12