Much of the conversation around MISO since the winter has been tied to renewables and the rapid growth displayed by solar in particular. Solar capacity (at least as it translated to solar MW on the MISO grid) has grown steadily for several years leading up to 2024. But since January of this year the growth has been explosive. The figure below plots average hourly MISO solar generation by month, going back to the start of 2020 with the blue bars in the top pane. The red line represents a running maximum instead of average solar output, as a proxy for actual observable, usable capacity in place. Overall, in 2023 this solar output rose by just over 700 MW, but over the first four-and-a-half months of 2024 the number has almost doubled, climbing 2.5 GW to reach 5.8 GW of generation from just solar during an hour last month in April.
Figure 1 | MISO Solar Generation Monthly Average, Running Mac, and Penetration Rate
We have discussed this growth in previous reports and market flashes, but the topic is increasingly germane as this month we are seeing the renewable growth start to have a material impact on MISO’s intra-day balancing efforts and price formation. The current changes are already meaningful and should only grow more important as we move into the summer. The change we can observe taking place in MISO is similar to one that has already taken place in ERCOT, showing up starting in the summer of last year. We called this phenomenon “ERCOT’s Solar Shift”, discussed most recently in the linked Special Report. The impact is large in ERCOT, which is already exposed to greater price volatility than other markets but it is notable that we are seeing a similar change already in MISO, despite solar representing a much smaller slice of the supply stack compared to ERCOT or CAISO.
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