> I'm not sure I like this. It seems that we're very clearly in the area of diminishing returns when it comes to solar panels. I don't follow this argument. Th

> I'm not sure I like this. It seems that we're very clearly in the area of diminishing returns when it comes to solar panels. I don't follow this argument. The median panels used in actual installations have increased in efficiency from about 16% to about 18% over the last 10 years (while the prices have more than halved). First, the chart you link to is for 'hero' cells, using expensive technology to test the limits of a particular material, it is only tenuously linked to industrial production. There's lots of leeway for improvement in industrial production, which is what matters to the economy. Second, improvements in efficiency are only one part of cost reductions. In the time that the cost of panels has dropped perhaps 50 fold you're only talking about a 1/3 to 1/2 increase in efficiency. Third, there's always potential for other materials or structures to come to the fore. If we could find a cheap way of producing multi-junction cells then the ~30% theoretical efficiency limit disappears. So, there's plenty of scope for continued improvements.