PECO implemented new commercial rates in March and I'm having trouble understanding how some of the charges are calculated. The new Schedule C has a "Distribution Demand Charge" and a separate "Transmission Demand Charge" but the tariff language about how they interact is unclear. One of my Philadelphia clients had a 340 kW demand in April, but their bill shows different kW amounts for each demand charge component. Distribution shows 340 kW but Transmission shows 298 kW for the same billing period. Has anyone else figured out how PECO is calculating these split demand charges?
PECO rate changes - anyone else confused?
Phil, I think the difference might be related to power factor corrections. Many utilities apply power factor adjustments to transmission demand charges but not distribution demand charges. Check your client's power factor for April - if it was below the tariff threshold (usually 85% or 90%), PECO might be calculating transmission demand using a corrected value. The math would be: measured demand ÷ power factor = billing demand for transmission purposes. That could explain why transmission demand is lower than distribution demand if the customer has a leading power factor above 100%.
I've been dealing with similar PECO rate confusion in Virginia with Dominion Energy's comparable tariff changes. The key document you need is the "Rate Schedule Rider" that explains how multiple demand charges interact. Walt is probably right about power factor corrections, but there could also be coincident vs. non-coincident demand differences. Transmission demand is often based on the customer's contribution to system peak, while distribution demand reflects their individual maximum. Request PECO's detailed billing calculation sheets - they usually show the step-by-step math for complex rate structures.
Thanks Walt and Phil - the power factor explanation makes sense. I checked the April bill and my client had an 87% power factor, so no correction would apply there. But Phil's suggestion about coincident vs. non-coincident demand might be the answer. I requested detailed billing calculations from PECO and they provided worksheets showing that transmission demand is based on the customer's usage during PECO's monthly system peak hour, while distribution demand uses their individual peak. In April, the client's peak demand of 340 kW occurred at 2 PM, but PECO's system peak was at 4 PM when the client was only drawing 298 kW. That explains the difference perfectly.