Donna C. from Harrisburg. I'm building an Excel model to compare time-of-use rates versus standard tariffs for commercial customers. Has anyone created something like this that accounts for both demand and energy charges across different time periods? PPL Electric has a TOU-GS schedule that's pretty complex with summer/winter differences and I want to make sure I'm capturing everything correctly.
Excel model for comparing TOU vs standard rates
Donna, Randy here. I've built several TOU comparison models over the years. The key is setting up your time period buckets correctly first - peak, off-peak, and shoulder if applicable, then separate tabs for summer and winter if the tariff differentiates. For demand charges, you need to track the billing demand for each time period separately, not just overall peak demand. Make sure you're also capturing any ratchet provisions where demand might be based on a percentage of the highest demand in previous months. I can share some template structures if that would help.
Cecilia K. in Cincinnati. Built one for Duke Energy Ohio's TOU schedules. One gotcha I found was that some TOU tariffs have different customer charges than the standard rates, so make sure you're comparing apples to apples there. Also watch for power factor adjustments that might only apply to certain rate schedules.
Carl from Pittsburgh here. For PPL specifically, their TOU-GS has a coincident peak demand component that can be tricky to model if you don't have 15-minute interval data. You might need to make some assumptions about load factor and diversity factor. Also their winter rates are significantly different from summer, especially the demand charges.
Randy, I'd definitely appreciate seeing some template structures. Carl, you're right about the coincident peak component - I'm having to estimate that based on the customer's historical load patterns. Cecilia, good catch on the customer charge differences. This is more complex than I initially thought!
Phil G. in Richmond. Built something similar for Dominion Energy Virginia's Schedule TOU-GS. One thing that helped was creating a summary table that shows the break-even point - what percentage of usage needs to shift to off-peak hours to make TOU beneficial. Makes it easier to present to customers.
Phil in Tampa here. Don't forget about any riders that might apply differently between standard and TOU schedules. Some utilities have environmental riders or renewable energy charges that vary by rate schedule. Also make sure you're using the correct effective dates - I've seen models get messed up when tariff changes happen mid-analysis period.
Great points everyone. Phil G., I like the break-even analysis idea. Phil in Tampa, I did catch some rider differences between the schedules that would have thrown off my analysis. This forum is incredibly helpful for catching these details!