That used to be true but I have read now that they pass that boundary within 1-4 years. I certainly hope that we will get that number down further. They do take a ton of energy to produce though. It is like buying organic food. It costs a lot more for now but as you vote with your dollars it will become more common and cheaper. The big thing is that it frees up your monthly income by not having an electric bill. Solar panels will surpass 20 years now without loosing efficiency, but they will last a whole lot longer while still pumping out free energy at a reduced rate.