There's a startup working on cost-effective panel-scale multi-layer cpv. http://www.zmescience.com/science/twice-efficient-residential-solar-cells/ http://www.

There's a startup working on cost-effective panel-scale multi-layer cpv. http://www.zmescience.com/science/twice-efficient-residential-solar-cells/ http://www.zmescience.com/science/twice-efficient-residentia... And instead of doubling of efficiencies(22% to 44%) , I've seen some thoerticak work talking about 60%+ .