Your idea is fascinating and recommendable as its cost effective  using solar, but still this plan is going to demand lots of bucks from you ranging from the purchasing of solar panels (depending on how many) to it's installation cost, then it's maintenance as time goes on. Not that I pray for it but do you have a back up plan to this your investment should it not yeild returns much as you expect it to.
Don't fuse  your mind on calculating time of investment returns also calculate the opposite too, in that way you will be sturdy and ready for any outcome as it surface. Good luck with your investment!!