Wisconsin Public Service charges $0.00 per kW for demand outside a ten-hour window. Whether that saves you anything depends on one thing, and it is not your peak.
Wisconsin Public Service charges $0.00 per kW for demand outside a ten-hour window. Whether that saves you anything depends on one thing, and it is not your peak.
Kenneth · Oshkosh · 2026-08-14
*Source: Wisconsin Public Service filed tariff, P.S.C.W. Volume No. 7, Amendment 802,
effective 1 January 2026. Every figure below is read from a filed sheet.*
Most Fox Valley plants are on Wisconsin Public Service Schedule Cg-20. It applies
once a site has exceeded either 100 kW of demand or 25,000 kWh a month.
On that schedule the demand charge is $20.080 per kW in summer and **$13.052
per kW in winter**. Those are large numbers. On a 300 kW site the summer figure is
just over $6,000 a month.
But they only apply inside a window.
| Season | On-peak window | Demand charge |
|---|---|---|
| Summer (Jun–Sep) | 8AM – 6PM, weekdays | $20.080 / kW |
| Winter (Oct–May) | 8AM – 1PM and 5PM – 9PM, weekdays | $13.052 / kW |
| All other hours | nights, weekends, every holiday | $0.00 / kW |
Not reduced. Zero.
CORRECTED 2026-08-16. The first version of this note said that if your peak
falls outside the window "you pay nothing for demand at all", and put the gap at
about $24,750 a year. **That was wrong, and I found it by building the calculator
rather than doing the arithmetic by hand.** The corrected figures are below and
the reasoning is at the foot.
Your demand charge is set by your highest fifteen-minute interval **that falls
inside the window** — not by your highest interval overall. Moving a single spike
out of the window does not take the charge to zero. It takes it down to whatever
your next highest in-window interval is, and for most plants that is still
substantial.
Three cases on a 120 kW site, summer, all computed from interval data:
| Monthly bill | Against Cg-5 | |
|---|---|---|
| Daytime plant — 74 kW during the window, peak at 11AM | Cg-5 is cheaper | Cg-20 costs you $407 a month more |
| Same plant, peak moved to 2AM | Cg-20 $4,137 | saves $6,210 a year |
| True night operation — nothing drawn 8AM–6PM | Cg-20 $2,444 | saves $35,863 a year |
**So the size of the prize depends entirely on how much load you have in the
window, and the honest range is nothing at all to about $36,000.**
Two things follow that matter more than the headline:
1. Cg-20 is the wrong schedule for an ordinary daytime plant. On the first
row it costs $407 a month more than the flat rate. Anyone who tells you
time-of-use is always cheaper has not run the numbers.
2. Moving one spike is worth much less than most people assume. The value is
in shifting load, not in shifting a peak — and only a plant that can
genuinely clear the window sees the large number.
Note the middle column. **Cg-20 is the wrong schedule for a plant that peaks at
eleven in the morning** — it costs about $350 a month more than the flat rate.
Anyone who tells you time-of-use is always cheaper has not done this arithmetic.
Cg-20's customer demand charge — $2.610 per kW — is billed on:
"maximum demand during the current or preceding 11 months"
A single fifteen-minute interval is therefore paid for twelve times. A
compressor test, a failed soft-start, a one-off simultaneous startup after an
outage. It sets a floor under your bill for a year, and nothing on the bill
announces that it has happened.
The same ratchet applies on Schedule Cp, above 1,000 kW.
Two optional schedules exist alongside the standard ones: Cg20-RR and
Cp-RR, Response Rewards. They cut the demand charge substantially in exchange
for exposure to critical peak events.
| Cg-20 | Cg20-RR | |
|---|---|---|
| Summer on-peak demand | $20.080 / kW | $15.060 / kW |
| Winter on-peak demand | $13.052 / kW | $9.789 / kW |
A 25% cut on the largest charge on the bill.
And the tariff says this, in writing:
"The Company reserves the right to limit participation to 25 customers."
Twenty-five on Cg20-RR. Twenty on Cp-RR. **Forty-five seats in the entire WPS
territory.**
Now the other half, which I have since read — and it changes the answer.
The trade for that discount is Critical Peak pricing: $0.46946 per kWh. That
is 8.5 times the ordinary on-peak rate. It can be called **up to 300 hours a
year**, *"anytime during On-Peak or Off-Peak periods at the sole discretion of the
Company"*, on one hour's notice.
On the same 120 kW site:
| Critical peak hours called | Your net position |
|---|---|
| 0 | +$10,675 |
| 100 | +$5,704 |
| 200 | +$734 |
| 215 | break-even |
| 300 — the permitted maximum | −$4,237 |
Break-even is 215 hours. They may call 300.
And clause 2 of the Special Terms is the sentence to read twice:
*"Any customer choosing to be served on this rate schedule thereby waives all
rights to any billing adjustments arising from a claim that the bill for the
customer's service would be cheaper on any alternative rate schedule for any
period of time…"*
So Response Rewards is not a discount. It is a demand response contract. It
pays if you can genuinely drop load within an hour. If you simply keep running
through the events, you lose money — and you have signed away the route to
complain about it.
**The qualifying question is therefore not "would you like 25% off your demand
charge."** It is: *can you shed load on an hour's notice, up to 300 hours a year,
and what does an hour of downtime cost you?* For a heat treater between batches or
a moulder able to stagger startups, that may be an easy yes. For a continuous
line, it is a trap.
I would rather tell you that than sell you the first half of it.
Power factor. WPS does have a clause — the benchmark is 0.80, and above it you
receive a credit — but the money is in the hundreds of dollars a year, not the
thousands. It is a real line and a small one, and anybody leading a pitch with it
is reaching for the smallest number available.
Anything about your specific site. I have read the tariff. I have not seen
your bills.
I read filed tariffs and publish what I find. Every figure above is sourced to a
sheet number so you can check it against Wisconsin Public Service's own filing
rather than take my word for it.
This is published research, not a service. I am not offering to audit anyone's
bills and I am not asking anyone to send billing data. If something here applies
to your site, take it to whoever handles your energy contracts — it is yours to
use, free, and you do not need me in order to act on it.
Kenneth · Oshkosh, Wisconsin
*Sheets referenced: Cg-1 E6.00, Cg-5 E6.01, Cg-20 E6.10–E6.11, Cg20-RR E6.15,
Cp E6.60, Cp-RR E6.70, Cp Rules E6.65, Cp-I2 E6.80. P.S.C.W. Volume No. 7,
Amendment 802, PSCW Order 6690-UR-128. All free at
wisconsinpublicservice.com/company/wi-tariffs — check me.*