We are putting at least four and perhaps five 100 watt solar panels from AM Solar on the roof of the 2015 23D. We installed a very low vent for the plumbing and replaced the stock Winegard batwing type antenna with the Winegard Rayzar automatic HD TV antenna. This allowed for the narrow solar panels to be either side of the exhaust fans, skylight and air conditioner.
These folks have a great solar primer you can read on line. We have purchased all the components for two system from these folks:
Welcome to AM Solar_Your RV Solar Specialists since 1987
Note that all solar panel "ratings" are under laboratory conditions. Top quality solar panels can see about 75% of the rated number or 75 watts from a 100 watt panel on a bright day with the sun directly overhead.
We removed the two stock Interstate lead acid batteries and are replacing them with one AM Solar 300 amp-hour lithium iron phosphate battery that weighs 84 pounds (about 8 pounds less than the two stock batteries) and has a 14.5" x 11.25" foot print and needs 11.25 of height space when installed. This battery will provide between 80 and 85% of it's rated power, or around 250 amp-hours. Lifeline GSM batteries will tolerate about a 50% power draw and the stock lead acid will tolerate a much lower percentage than the Lifeline batteries.
The battery is mounted just forward of the street side wheel well under the dinette with the Magnum MSH-3012 hybrid charger/inverter/converter mounted adjacent. The Blue Sky solar charger control box is mounted behind the microwave above the refrigerator. The BlueSky control head and the Magnum control head are mounted on a hickory panel below the television.
As a comparison in terms of weight, for our Classic, we replaced four 300 amp-hour Lifelines (the four weighed 372 pounds) with their custom stainless steel battery enclosure with a single 600 amp-hour lithium iron phosphate battery (weighs 168 pounds with four 3.2Vdc modules of 42 pounds each) that is now under the sofa. We were able to shed over 175 pounds of tongue weight down to just under 1,200 pounds. Our usable power went from 300 amp hours with the Lifeline batteries to over 500 amp hours with the lithium iron phosphate battery.
My experience with our 2013 25FB with a dealer installed 155 watt solar panel, Zamp controller and using the factory solar pre-wiring with #10 wire was it could not recharge the two stock Interstate batteries to full capacity after the furnace ran most of the night. The days were cloudless and bright sunshine. We had to use a 2,000 watt generator to get the batteries fully charged for the next night furnace use.