To my thinking this is yet a third dimension, but still not really directly mappable to rejected energy.

if we want to, we can view a solar cell as "burning" materials used to construct them over their 25 year amortized lifetime.

Really in building an apples to apples comparison of these alternatives we should skip all talk about marginal cost and rejected energy, and simply look at the levelized cost per Kwh.

by that measure, solar is indeed kicking ass. the only large issue is that all of its levelized costs are up front costs. but in long run it is already a win to go solar.