A new method using nanowires can make solar panels much more efficient and much cheaper

https://techxplore.com/news/2021-11-method-nanowires-solar-panels-efficient.html

"ultrahigh power-per-weight ratio solar cell that is more than 10 times more efficient than any other solar cell, by using GaAs in a nanowire structure... Gallium arsenide (GaAs) is the best material for making high efficiency solar cells because of its extraordinary light absorption and electrical characteristics... If this is placed on top of a traditional silicon-based solar cell, it could potentially double the efficiency of today's Si solar cells at low cost"