instead of going for higher efficiency, why not go for cheaper?
seldom do i see a roof entirely coated in solar panels. a roof replacement costs around 10k.
there certainly is a price-performance curve, but lower-efficiency shittier panels would still offset a non-zero amount of power costs. most roofs have zero real estate occupied by solar panels, so why would it not be rational to pursue manufacturing cost reductions, to the detriment of overall output?