[rabscuttler]

No worries at all!

Regarding the technology comparison, that is true from a power system point of view - but for a utility which is making investment decisions in new generation capacity, it isn't so different. We include carbon taxes because coal power operators suffer that tax, it isn't an assumption about future policies. And equally to someone else's question about whether subsidies are included in solar costs, the answer is no. Because the LCOE is calculated from current module, balance of system and soft costs, and that while subsidies have brought the costs down, they aren't a component of the LCOE. As for system costs which perhaps you are referring to, that is fair from the system viewpoint but not particularly for the marginal unit of new capacity. UKERC have done some good research in the UK on system costs of renewables integration which perhaps you are referring to [0].

But you're absolutely right that there is a lot of nuance, especially around regional power market differences.

[0] https://www.carbonbrief.org/in-depth-whole-system-costs-rene...

[chris_va]

> but for a utility which is making investment decisions in new generation capacity, it isn't so different.

You are probably familiar with all of this, but that's a tricky one since dispatchability puts those into different equivalence classes. California ISO has negative LMPs right now, which means building additional solar provides little marginal value to the utility. As a result, even if the "traditional" LCOE for solar (just using capital cost, O&M, and capacity factor) is lower than coal, coal would technically still have higher value to the utility.

You'd have to model real-time demand and fratricide to get a average marginal rate (almost impossible to predict for a 20-30 year horizon right now, given rate of innovation), and then compare that against the amortized capital cost and O&M to get an expected ROI for the plant. An LCOE comparison wouldn't really make sense from a decision making standpoint.

That wouldn't be true if they were both closely equivalent (say NGCC vs NGCT, or coal vs nuclear). Then a strict LCOE comparison would be useful.

[rabscuttler]

Fair point about California's negative LMPs, but I think for a lot of regions in the US there is still a lot of room for renewable growth.

But it is fair to compare LCOEs because solar usually gets its value through long-term PPAs; either utility to generator, or even through the rate-base, and the price of that is effectively set by the LCOE. Despite missing out a lot of the other factors that you reasonably bring up, from system costs to locational factors.