Donna H. in Nashville here. Working on a manufacturing client with 850 kW peak demand who's considering switching from TVA Schedule MSB to GSA-3. The demand charge structures are completely different - MSB has seasonal tiers while GSA-3 is flat rate year-round. Anyone have a good Excel template for modeling these side by side?
Excel model for comparing demand charge structures?
Jeff C. also in Nashville - I've been down this road with TVA comparisons! The tricky part is MSB has that weird summer demand ratchet that carries forward for 11 months. You need to model at least 2 years of billing to see the real impact. I built a model that pulls in 15-minute interval data if you have it.
Randy Dawson here. This is exactly the kind of analysis where the details matter enormously. TVA's MSB schedule has that 80% ratchet provision that trips up a lot of people. The summer peak demand (June-September) gets locked in at 80% minimum through the following May. For your 850 kW customer, if they hit 850 kW in July, they're paying demand charges on at least 680 kW every month until next summer even if actual usage drops to 400 kW. Make sure your Excel model accounts for this ratchet mechanism because it can completely change the economics of the rate comparison.
Brenda J. from Birmingham - we deal with similar issues with Alabama Power. Randy's absolutely right about those ratchet provisions being killers. One thing I add to my models is a sensitivity analysis - what happens if demand varies by +/- 15% from historical averages? Manufacturing clients especially can have equipment changes that affect their load profile.
Thomas B. in Charleston - don't forget about power factor adjustments in your model! TVA has pretty strict PF requirements and penalties can add up fast for inductive loads. Also check if your client qualifies for any economic development riders that might affect the base rates.
Great points everyone! Jeff, I'd love to see how you structure the ratchet calculations. Thomas, good catch on power factor - this client runs a lot of motors so that could definitely impact things. Randy, that 80% ratchet is brutal, I'm seeing it would cost them an extra $18K over the winter months based on their summer peak.
Anita W. from Fargo - we don't have TVA up here but similar concept with Minnkota Power. One trick I learned is to graph the monthly demand charges visually in Excel rather than just looking at totals. Sometimes you can spot seasonal patterns that suggest load management opportunities that offset rate differences.
Donna, I'll email you my TVA template through the forum system. It's got tabs for MSB, GSA-1, GSA-3, and a comparison summary that shows breakeven points. The ratchet calc is in column M with conditional formatting to highlight when it's kicking in.