I used the Snow Joe on my solar panels this winter and was very impressed. The 21' length was necessary to get to the top of the panels and is a bit hard to maneuver, but the rake did the job with both light and heavy snow falls.
This rake is easy to put together, but make sure you tighten the nuts well or check them after each use. I lost one that holds one of the braces to the plastic rake head. The plastic rake seems to be less harmful to asphalt shingles than my old aluminum one. Know that it's difficult to change the length of the handle once you've used the rake as snow gets inside and freezes up the pieces that screw apart.
This thing is a beast. When fully extended it will reach some pretty ridiculous spots on your roof. Cleared out the snow around an ice dam on my second story roof without having to stand on a ladder (although I was standing on top of a large snowdrift, but still impressive reach).
I love using the Snow Joe Telescoping Snow Joe Shovel Roof Rake. It clears my rooftop solar panels and roof from light or heavy snow. It is light weight and easy to use. I am short and not strong, but I have no problems with this product. It has made a big difference in my power output this winter. Also, Snow Joe has outstanding customer service!
I am very impressed by this product it is very sturdy and very easy to make it short or make it long very easy to assemble took no more then 5 minutes as I said it is a much better product then the one I purchased in town about 5 years ago