Golden_HVAC - we have a 34' 5th wheel with 6 x 235 W panels. We went on roof with a template of one of these panels (a piece of cardboard cut the correct size) and found we had room to install two more easily, three more not quite as easily and 4 would require setting them 12" off deck to clear the a/c housing. This would require re-wiring, perhaps an MPPT-60 or another MPPT-45 (for two strings of 4 in series or three strings of 3 in series).
"...Chinese Companies like SunEdison have publically targeted $0.40 cent per watt panels by the end of 2016, and many Tier 1 Chinese manufacturers are achieving sub $0.50/w already in 2014. :Given that most manufacturers are improving 1-2 cents per quarter, less than ten cents improvement (to reach $0.40) over the next 12 quarters is likely conservative..." (http://cleantechnica.com/2015/01/29/solar-costs-will-fall-40-next-2-years-heres/) Right now, the consumer can buy them for less than $1/watt in bulk.
Believe that a 500 W window/split-level for bedroom would be an excellent idea.
Reed and Elaine