Concentrator photovoltaics
Could this be a scalable solution for solar power?
- Verdict so far: Probably not.
Concentrator photovoltaics are based on the following idea: Instead of making a full photovoltaic solar panel, make a much smaller one, make it heat-resistant, and give it a huge lens to focus more sun on it.
Note: This page mostly about designs where the sunlight is highly concentrated - let's say, 8x or more. Weaker magnifications aren't that helpful in overcoming the challenges of conventional photovoltaics anyway.
Cloudy days
Unlike conventional photovoltaics, concentrator photovoltaics don't work on overcast days. There may be lots of diffuse light in the sky, but the lens can't focus it.
Extra energy storage could help somewhat, but only in places where there are just a few overcast days in a row. It won't help in places where there's little direct sunlight for weeks or months at a time.
Adapting to sun angle
As the sun angle changes throughout the day, the lens focuses the sunlight onto a different point. There needs to be some sort of active motor system to correct for this, to keep the photovoltaic component in the focal point. Who knows the environmental footprint of such a system? It might (or might not) outweigh all the benefits of the solar power. [RESEARCH needed] [QUANTIFICATION needed]
Scarce minerals
The rare mineral content is proportionally less than conventional solar panels, because the photovoltaic unit is much smaller. But it still might not be low enough. [RESEARCH needed] [QUANTIFICATION needed]
Energy in production
Fresnel lenses are lightweight and cheap. Think of the sort of flexible plastic magnifying glass you can buy at a dollar store (thin and the size of a piece of paper). Concentrator photovoltaic panels use large arrays of these; each with a small photovoltaic unit behind it.
However, if the "adapting to sun angle" problem can't be also solved cheaply, then the whole system would likely take a lot of energy to make. Thus, the EROI is still unknown.