"Current solar cells have approximately 20 percent efficiency." Not the vast majority of commercial ones (closer to 10-15% range, afaik - the ones that get aro

"Current solar cells have approximately 20 percent efficiency." Not the vast majority of commercial ones (closer to 10-15% range, afaik - the ones that get around 20% (for non-concentrating) are in the lab or on satellites), and certainly not the cheaper thin film (GICS) kind with which this will compete.