A specialist from one of the companies distributing and retailing solar panels brought up a question for discussion that is not usually very specifically talked about but was raised by a client of theirs. The client was looking for the most efficient panels in terms of peak power (rated watts) per square foot of the panel (module) the way it was commercially available.
He was not interested to hear about the comparison between the different technologies in particular because they are usually compared on cell level and the data available is usually from scientific lab test not necessarily directly related to the realistic efficiency of the finished panel. When cells are actually implemented in the configuration of the panel there might be numerous factors additionally affecting the power-to-physical-area efficiency of the panel.
