Last Spring, both DAM and RTM midday prices in SP15 started routinely dropping into deeply negative territory, with prices falling much lower than we had seen in any year prior. Instead of prices settling in the range of $0 to -$10/MWh when solar energy became too abundant, suddenly we saw -$50/MWh prints in both DAM and RTM. Rattled solar developers were quick to attempt to write off 2024 as a fluke, frequently citing transmission derates on the PDCI and unsustainably high REC prices as causes of this anomaly. But, so far, Spring of 2025 appears to be on track to deliver more of the same.

Figure 1 – Frequency and intensity of renewable pricing, SP15 DAM (February in dark blue)

There are a lot of ways to measure low energy prices. Above, we split the question into two metrics, one for frequency and one for severity. On top, we have the percentage of solar hours (HE 10-16) each month which have implied heat rates of less than 1 mmbtu/MWh. These are hours in which renewables are clearly on the margin, since no thermal plant can economically dispatch at a HR of 1 or less.