Isnt that because all commodities have become hedge fund spec?
Plus the fact they are diminishing supply?
Investing in solar rollout is trusting a source of energy that is as close to infinite as we'll ever need.
There would be risk of some inflation during short to medium term due to bandwaggoning/carpet-bagging but it would settle down when the train got rolling and the thrillseekers went looking for a bubble with more quick profits.
Plenty sunshine for everyone to get pie.

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty