The duration and thickness of smoke from Canadian wildfires that drifted over the eastern U.S. and into the PJM footprint last summer was nearly unprecedented, affecting solar generation output and altering typical demand for electricity.
Marcus Smith, Lead Engineer, Load Forecasting – Markets Coordination, reviewed the wildfires’ effects (PDF) on the PJM grid at the Jan. 30 annual meeting of the American Meteorological Society, the theme of which was “Living in a Changing Environment.”
Smith highlighted the two 2023 smoke events that most impacted solar output and electricity demand: the periods of June 5–11 and June 26–July 1.
The first smoke event affected the eastern part of the PJM footprint more, with thick smoke reducing visibility and greatly reducing solar generation – particularly in the Mid-Atlantic Region, which is rich in behind-the-meter, or customer-based, solar generation.
The second smoke event was more spread out over the entire footprint, with the thickest smoke in PJM’s Western Region.
At least three episodes of near-surface smoke occurred, which decreased visibility and led to cooler-than-expected temperatures.
As thicker smoke developed over areas with a high coverage of solar panels, there were sudden and significant drops in solar generation during the time around and after solar noon. Solar generation was reduced by as much as 15% during the thickest of the smoke.
The smoke also caused temperatures to come in as much as 6 degrees cooler than forecast, leading to a decrease in demand of more than 3% of expected levels at times.
The erratic nature of the wildfire smoke made it difficult to forecast its impacts to the bulk electric system, Smith said.
Typically, load does not dip during peak sunlight hours when temperatures are very warm in the summer and air-conditioning use is high. However, this did occur on multiple occasions of thicker near-surface smoke.
Other factors may have played a supporting role in the load and solar generation impact, but the presence of smoke was a clear factor in their behaviors.