A couple points: 1. These numbers are from a 2015 report that was probably prepared in 2014 and calculated using data from several years before the report was

A couple points: 1. These numbers are from a 2015 report that was probably prepared in 2014 and calculated using data from several years before the report was written. Solar tech has improved a lot in the last couple decades. 2. The graph is measured in tonnes per TWh, not thousand tonnes per TWh, so that might be part of the confusion. 2700 tonnes per TWh is high, but reasonable. My estimate would be closer to 1000-1500 tonnes/TWh. 3. You are correct that mass is a pretty useless metric. A more important metric would be energy payback time (how long before the power source produces enough energy to make a copy of itself, essentially). For modern solar this is measured in months, possibly up to a year or two in extreme cases. For nuclear, this is probably measured in days or weeks, since nuclear power plants produce so much energy. However, when looking at power plants with lifetimes measured in decades, the difference is insignificant. Both nuclear and solar are fantastically better than any fossil fuel.