Transparent solar cells are inefficient compared to opaque solar cells and traditional concentrators. Transparent solar collectors let most visible light through that can be turned into solar energy. Commercial solar cell efficiency is already low, about 20 percent efficient, but that’s much higher than the 1 percent efficiency of transparent solar concentrators.
The transparent solar concentrator collects infrared and ultraviolet light that’s invisible to humans as it passes through the solar collector on a sunny day. This light is then converted to electricity by strips of solar cells at the edge of the transparent panel.
It’s impossible, however, for solar concentrators to work well when strapped to the sides of buildings because they only work when directly facing the sun. Commercial solar plants are set up to “track” the sun, increasing their efficiency by 25-35 percent. Even the kind of stationary rooftop solar panels used by private citizens which do not track the sun are generally specially oriented on top of roofs and at angles so they face the sun for the maximum amount of time each day. Without tracking, transparent solar collectors aren’t capable of delivering electricity throughout the day or when the building itself blocks the sun.
More importantly, solar collectors are expensive. Industrial solar power systems currently produce electricity at roughly $5,067 per kilowatt hour, not including the 30 percent federal tax credit for solar panels. The capital costs to deploy transparent solar concentrators are even more expensive — at least four times higher than solar power systems. Compared to a natural gas-fired power plant, transparent solar concentrators are a costly way to generate power.