You also don't usually use the same exact kind of panels as terrestrial solar farms. Since you are going to space, you spend the extra money to get the highest possible efficiency in terms of W/kg. Terrestrial usually optimizes for W/$ nameplate capacity LCOE, which also includes installation and other costs.
It is similar to the biological tradeoff of having a few offspring and investing heavily in their safety and growth vs having thousands off offspring and investing nothing in their safety and growth.