Why solar panel is so expensive and can replace by cheaper one at similar performance?

Quality and Marketing.

One of the biggest fads around right now is going green. Demand = High Price. I was looking into making my own, but the precision and chemicals required to make the silicon solar cells are way above my level and monetary discipline. I found a way to make them using copper panels, but their efficiency is about 1/10 of the silicon ones, and copper isn't all that cheap especially when you need ten times the square footage of normal panels. Weigh your options I guess.