The West was once wild, with wide rivers, cowboys driving stampedes, and growing population centers seeking steady sources of electricity. Over the course of the 20^th century, massive hydroelectric projects tamed the rivers and, in combination with natural gas, offered a steady stream of MWs to the developing WECC. The status quo was not perfect, with demonstrated potential for major scarcity events when either water or MWs got tight, but for the most part it made for steady daily operations as a series of dispatchable energy resources provided power. WECC’s 20^th century power landscape has given way to solar as it is the poster child of the 21^st century.  The growing capacity of this parabolic shaped resource serves as a foundation for a showdown at sunrise that pushes through the middle of the day and only ends when the sun sets. The significant increase in solar capacity in California and the Desert Southwest over the past three years has necessitated earlier stints of renewable curtailments to ensure grid stability.

Figure 1 | WECC Annual Solar Additions by Region (MW)

The early to mid-2010s brought a furious pace of solar development to CAISO, quickly redefining the grid. This was driven in part by the falling cost of photovoltaics, but also California’s Renewable Portfolio Standard (RPS).