The theory behind time-of-use electricity pricing is simple. Charge more for electricity when demand is highest, and consumers will either reduce the amount they use or shift their consumption to a lower-cost time of day. However, quantifying that impact isn’t so simple.

Yes, you can compare electricity consumption before and after time-of-use pricing is introduced. However, weather changes from year to year, affecting how much people use fans, air conditioners, furnaces and space heaters.…