Working on Arizona Public Service account with time-of-use demand charges. Summer on-peak demand rate is $19.50/kW but winter drops to $11.25/kW. Customer hit 380 kW peak in July during 3-6 PM on-peak period. Do TOU demand charges follow same ratchet rules as regular demand?
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Time-of-use demand charges - seasonal rates
Carl's right about separate ratchets. APS is tricky though - they also have seasonal ratchet resets. Summer ratchet expires in October, winter ratchet starts fresh. Check tariff Schedule E-32 for details.
Thanks Gina. Looking at E-32 now. So the July 380 kW on-peak would create ratchet through September, then reset for winter season? Customer's winter demand is much lower, usually 180-220 kW.
Dana, that's correct for APS. Seasonal reset helps customers with weather-driven loads. Your customer saves big in winter - 220 kW at $11.25 vs being stuck with 380 kW ratchet all year.
Hannah, exactly. Customer would pay $1,800/month extra if summer ratchet carried through winter. The seasonal reset saves them serious money. Good tariff design for desert climate.
Also watch APS for different TOU periods between seasons. Summer on-peak is 3-8 PM, winter on-peak is 5-9 PM. Easy to miss when auditing demand charges across seasonal boundaries.
Dana, most TOU tariffs apply ratchet separately to on-peak and off-peak demand. So July on-peak establishes ratchet for on-peak billing, but off-peak demand has its own ratchet calculation.