Impacts from Smoke on Solar Generation and Load in PJM Interconnection's RTO in Summer of 2023

Smoke from Canadian wildfires drifted over the eastern U.S. during the summer of 2023. The duration and thickness of the smoke in the PJM Interconnection RTO was nearly unprecedented and had affected solar generation output and altered typical load behavior. The erratic nature of the wildfire smoke made it difficult to forecast its impacts to the bulk electric system. At least 3 episodes of near-surface smoke occurred which reduced visibility and led to cooler than expected temperatures. Solar generation in PJM Interconnection’s RTO was hampered by the smoke. Reductions in solar generation output reached up to 15% of what typical solar generation would be during the thickest of the smoke. As thicker smoke developed over areas that with a high coverage of solar panels there were sudden and significant drops in solar generation during the time around and after solar noon.

The effect of the smoke also caused temperatures to come in as much as 6 degrees cooler than forecast. The combination of the reduction of solar and the lower temperatures led to a reduction of the load at over 3% of expected levels at times. Typically load does not dip during peak sunlight hours when temperatures are very warm in the summer however this did occur on multiple occasions of thicker near-surface smoke. Other factors may have played a supporting role on the load and solar generation impact but the presence of smoke was a visible determinant on their behaviors. This presentation will address the smoky days and their impact on solar output and load reductions as well examine the performance of the load forecast models during these smoke events.