Seasonal variations in solar energy production

 https://carboncounter.wordpress.com/2015/08/11/germany-will-never-run-on-solar-power-here-is-why/

Why is the Texas electrical grid so fragile?

Texas doesn't have a reliable grid because wind and solar could never offer significant value if the requirements for dependable electricity were written down and enforced. And the politicians decided that growing wind and solar was more important than reliable power. And so the people of Texas paid the price for that decision.

https://judithcurry.com/2021/02/18/assigning-blame-for-the-blackouts-in-texas/

Traditional fossil fuel generation has (as does most hydro and nuclear) inherent capacity value. That means such resources generally can be operated with a high degree of reliability and dependability. With incentives they can be operated so that they will likely be there when needed. Wind and solar are intermittent resources, working only under good conditions for wind and sun, and as such do not have capacity value unless they are paired with costly battery systems.

If you want to achieve a higher level of penetration from renewables, dollars will have to be funneled away from traditional resources towards renewables. For high levels of renewable penetration, you need a system where the consumers’ dollars applied to renewable generators are maximized. Rewarding resources for offering capacity advantages effectively penalizes renewables. As noted by the head of the PUC in Texas, an energy only market can fuel diversification towards intermittent resources. It does this because it rewards only energy that is fed into the grid, not backup power. (Side note-it’s typical to provide “renewable” resources preference for feeding into the grid as well. Sometimes wind is compensated for feeding into the grid even during periods of excess generation when fossil fuel resources are penalized. But that’s another article. )

Traditional planning studies might recognize that wind needs to be backed up by fossil fuel (more so under extreme conditions) such that if you have these backup generators its much cheaper to use and fuel them, than to add wind farms with the accompanying significant investment for concrete, rare earth metals, vast swaths of land …. . Traditional planning approaches often have to go(be abandoned) to get around this “bias” of favoring capacity providing resources over intermittent resources.

When capacity value is rewarded, this makes the economics of renewables much less competitive. Texas has stacked the deck to make wind and solar more competitive than they could be in a system that better recognizes the value of dependable resources which can supply capacity benefits. An energy only market helps accomplish the goal of making wind and solar more competitive. Except capacity value is a real value. Ignoring that, as Texas did, comes with real perils.

In Texas now we are seeing the extreme shortages and market price spikes that can result from devaluing capacity. The impacts are increased by both having more intermittent resources which do not provide capacity and also because owners and potential owners of resources which could provide capacity are not incentivized to have those units ready for backup with firm energy supplies.