Historical load factors are calculated using the 60d SCED Generation Resource Data. Specifically, we consider the total high sustained limits (HSLs) for all wind and solar generation at each time stamp. This, expressed as a percentage of nameplate capacity for both technologies respectively, gives a 15-minute load factor time series.

For each zone we calculate separate load factors to account for the varying weather conditions and consequent power production potentials of different renewable generation sites.

For the forecast, we use the 2022 weather year. That is, we assume the same 15-minute load factors for wind and solar as were observed in 2022. When multiplied by the available nameplate capacity for future years, this gives us the uncurtailed power output of renewables.

Assumptions

Curtailment

We should note that for our purposes, the load factors discussed above do not include curtailment. For example, a 10 MW wind farm, which (due to current weather) is capable of outputting an average of 5 MW for the next hour but is curtailed to 0 MW due to transmission constraints, would still be recorded as a 50% load factor.

This is factored into our modeling through the use of HSLs as oppose to basepoints in our load factor calculations.

Caveats

Single weather year

It's important to acknowledge that weather patterns can vary significantly from year to year due to climate variability and extreme weather events. Therefore, while a single historical year provides a useful baseline for modeling purposes, it may not capture all potential weather scenarios.