As someone with a physics degree and who has taught high school physics (lamentably… and i know there’s a lot wrong with what we teach, anyways), and currently as an engineer interfacing with the renewables field; i can confidently clear this one up. Most of the radiation from the sun is transferred into the water, a very small fraction is reflected, even if it is a fraction that will produce a sunburn. Although I’ve never come across anyone claiming reflected sunburn and find it hard to accept. Sadly it’ll be a complete waste of time mounting panels on the back – you lose so much in potential energy converted from non-direct incidence. Basically the best thing you can do is angle your panels in a way so they face the sun directly for as much of the time. I think you’d be lucky to get anything close to 5% from a backward mounted panel. Admitedly this is a guess, its not worth doing the calcs and solar panels dont do a lot with diffuse radiation. Hopefully in about ten years we should have solar panels with double efficiency (like 30%), but this likely to be the limit of the technology. We can still hope for better solutions. Ever come across this? energyfromthevacuum.com ? I’m trying to research alternatives like high powered magnet heating and EM generation – its all viable, we just dont have manufactured products yet. Keep your eyes peeled!