Higher-performance panels are preferable for scaled-down roof spaces because they can make a lot more power inside of a scaled-down space. Feasibility of installing solar panels with out a contractor: It's not necessarily feasible to set up solar panels with no contractor on some different types of roofs, like slate https://bluetechsolarcell.com/solar-cell-%e0%b8%81%e0%b8%b1%e0%b8%9a-solar-rooftop-%e0%b9%81%e0%b8%95%e0%b8%81%e0%b8%95%e0%b9%88%e0%b8%b2%e0%b8%87%e0%b8%81%e0%b8%b1%e0%b8%99%e0%b8%ad%e0%b8%a2%e0%b9%88%e0%b8%b2%e0%b8%87%e0%b9%84%e0%b8%a3/