With the right techniques, RVing can be a very efficient, non-polluting lifestyle. The best resource about retrofitting your RV to be more efficient is Phred’s “Poopsheets” which are free, compact information guides written by an experiencd RVer.
Topics include water treatment, solar power, efficient heating and cooling, composting toilets and efficient 12V appliances and lighting.
For solar power, he directs readers to the RV Solar Electric web site by Noel and Barbara Kirby, which he says “includes about everything you need to know [about solar power for RVs] and includes details on RV installations not found elsewhere. Ask for his added sheets on sizing a system when ordering.” The Kirbys’ also publish RVer’s Guide to Solar Battery Charging, which was last updated in 1993, but is still a great guide.
When purchasing an RV, Phred recommends visiting the RV Consumer Group, which a nonprofit organization that rates RVs.
But you might be better off buying a empty RV with a good structure and installing the components yourself, as explained here.