Maine Cannabis Cultivation Facility Energy: Winter Heat, CMP Demand Classes, and Standard Offer Exposure

How CMP and Versant interval charts read a Maine canopy

On the utility side, cultivation registers as a photoperiod square wave plus a cold-weather overlay: steady kW when lamps are on, lower kW overnight, and extra draw when boilers, reheat coils, or steam humidifiers chase sub-freezing makeup air. With 7,758 heating degree days statewide, that overlay runs roughly eight months a year [noaa-cag-maine].

At CMP, Small General Service serves accounts under 20 kW with no demand charge; Medium General Service serves secondary voltage accounts from 20 kW up to 400 kW; Intermediate General Service covers on-peak demand from 400 kW to 1,000 kW; and Large General Service applies above 1,000 kW [cmp-mgs-tariff]. Medium and larger classes pay per-kW distribution and transmission demand charges [cmp-mgs-tariff].

Maine counted 76 active adult-use cultivation facilities as of September 2026 [ocp-adult-use-licensee-search]. Most standard indoor grows will sit on MGS or IGS once flowering rooms energize.

Canopy watts and the 20 kW CMP threshold

Take 6,000 square feet of flowering canopy at 35 W per square foot under horticultural LEDs as a modeling example, not an OCP standard. Energized fixtures draw 210 kW on a twelve-hour schedule. Veg and mother rooms might add 40 kW for about 250 kW before HVAC starts.

250 kW clears CMP's 20 kW Small General Service cap and lands the account on Medium General Service with per-kW distribution and transmission demand [cmp-mgs-tariff]. Dollar charges live in the live tariff PDF; the MGS sheet defines class placement only.

Fixture efficacy and photoperiod drive this number more than any other commissioning choice; walk through HPS versus LED on the lighting cost page.

HVAC and humidification in a 7,758 heating degree day climate

Maine runs 7,758 heating degree days and 238 cooling degree days in a normal year [noaa-cag-maine]. Summer humidity along the coast is moderate and short; the bigger year-round issue is sub-freezing winter air that drives humidification and lighting-heat recovery in sealed rooms [noaa-cag-maine]. The weatherization page covers envelope decisions that reduce winter heat load.

Continuing the example: assume the HVAC plant draws 120 kW at winter peak when outdoor air is below 10 F and 60 kW on an average winter day, with 30 kW of pumps, fans, controls, and office load year-round. Winter peak demand is then 250 + 120 + 30 = 400 kW, right at the IGS threshold. Summer peak, with the heating plant off and minimal cooling needed, might be 250 + 40 + 30 = 320 kW.

That 400 kW winter peak moves the account toward Intermediate General Service and the large non-residential standard offer class, which floats on wholesale prices [mpuc-cmp-large].

Annual kWh sketch for the 6,000-square-foot example

Cited EIA and climate figures are facts; other table inputs are illustrative. Annual energy:

Load	Assumption	Annual kWh
Flower lighting	210 kW, 12 hours a day, 365 days	919,800
Veg and mother lighting	40 kW, 18 hours a day, 365 days	262,800
HVAC and humidification	80 kW average across the year	700,800
Pumps, fans, controls, office	30 kW continuous	262,800
Total		2,146,200

At the EIA June 2026 Maine commercial average of 22.24 cents per kWh, that is about $477,000 a year all-in [eia-epm-5-6-a]. At the Maine industrial average of 14.21 cents it would be about $305,000 [eia-epm-5-6-a]. The 8 cent gap between those averages is why class placement and a fixed CEP contract matter.

CMP sets per-kW delivery demand in the tariff; no CEP supply contract changes those lines. Pull current dollars from the MGS or IGS sheet before budgeting; here treat peak kW as its own cost center. Demand charges show how overspecified hydronic plants inflate that peak.

Burner CO2 and winter reheat

Liquid CO2 barely moves the meter beyond regulators. Gas-fired enrichment adds sensible heat and moisture the HVAC must handle, and in Maine that usually appears as boiler or electric reheat on makeup air, not chiller load [noaa-cag-maine]. Stack the indirect kWh on the CO2 supplementation page.

Standard offer tiers if you stay on default supply

Medium non-residential standard offer gets fixed monthly prices from the PUC's annual bid [mpuc-cmp-large]. Large non-residential standard offer is indexed to wholesale and reset each month, with CMP 2026 energy from 7.23 cents in May to 18.23 cents in January plus a capacity charge [mpuc-cmp-large]. A grow that crosses into the large class without signing a CEP contract carries full winter wholesale exposure. A fixed, index, or block-and-index contract with a licensed CEP is the hedge.

Three commissioning choices Maine operators regret

1. Territory before supplier quotes. CMP southern territory sits in ISO New England with one CEP pool; Versant Maine Public District in Aroostook runs under NMISA with higher indexed standard offer and a 50 kW minimum billing demand on Rate E-P [versant-mpd-tariffs].
2. Transformer size for canopy you will not light this year. Requesting 400 kW service for Tier 2 buildout creates demand charges before flower rooms energize.
3. Envelope before fixture swaps. At 7,758 heating degree days, air sealing and roof insulation often cut winter peaks more than changing a batch of lamps [noaa-cag-maine].

Tier canopy and standard offer class crossover

OCP lists 76 active cultivation facilities across Tier 1 through Tier 4 canopy sizes [ocp-adult-use-licensee-search]. A Tier 3 or Tier 4 indoor site often crosses CMP Medium General Service into Intermediate or Large General Service and the large non-residential standard offer class [cmp-mgs-tariff] [mpuc-cmp-large]. Model winter peak kW when outdoor air is below 10 F, not summer lighting peak alone [noaa-cag-maine].

Medical caregiver load outside OCP testing rules

Maine's medical program still has no mandatory contaminant testing or statewide inventory tracking [ocp-medical-use]. Caregiver and medical dispensary cultivation may sit on residential-adjacent service sizes with different tariff treatment than adult-use licensees [ocp-medical-use]. Adult-use facilities should not assume caregiver sites face identical demand charges [ocp-medical-use].

Procurement calendar for CMP large class

Large non-residential standard offer resets each month on wholesale index [mpuc-cmp-large]. Sign fixed CEP contracts before October if January indexed prices repeat 2026 patterns [mpuc-cmp-large]. Medium class fixed monthly prices also swing: CMP 2026 medium energy from 8.76 cents/kWh in May to 19.52 cents/kWh in January [mpuc-cmp-medium].

Versant E-P minimum demand floor

Maine Public District Rate E-P bills a distribution demand charge of $11.87/kW plus transmission $9.27/kW with billing demand the greater of 15-minute maximum or 50 kW [versant-mpd-tariffs]. A 40 kW measured peak still bills 50 kW [versant-mpd-tariffs]. Northern Maine operators must not assume CMP class thresholds apply [versant-mpd-tariffs].

OCP tier expansion and service requests

Tier 3 and Tier 4 canopy expansion requires matching electrical service requests before energizing new rooms [ocp-adult-use-licensee-search]. Requesting 400 kW service for Tier 2 buildout creates demand charges before flower rooms energize [cmp-mgs-tariff].

Envelope before fixture swaps

At 7,758 heating degree days, air sealing and roof insulation often cut winter peaks more than lamp swaps alone [noaa-cag-maine]. Efficiency Maine custom track should precede CEP contract signature when capex is planned [efficiency-maine-at-work]. Territory choice between CMP and Versant MPD is irreversible for standard offer pricing [mpuc-mpd-large].

Tier 3 canopy and IGS threshold

Assume 6,000 square feet Tier 3 flower canopy at 35 W/sq ft input and 210 kW lighting load. Winter HVAC peak can push total demand toward 400 kW at CMP [noaa-cag-maine] [cmp-mgs-tariff]. That crossover moves supply default toward large non-residential indexed standard offer [mpuc-cmp-large]. Sign fixed CEP supply before energizing expansion rooms [mpuc-standard-offer-rates].

Fixed CEP before winter index

Sign fixed CEP supply before October if January indexed large-class prices repeat 2026 patterns [mpuc-cmp-large].

Supplemental tariff and procurement detail

Sign fixed CEP contracts before winter indexed standard offer repeats January 2026 patterns [mpuc-cmp-large]. Compare Maine commercial rates for class thresholds [cmp-mgs-tariff].

Additional procurement and tariff notes

OCP lists 76 cultivation facilities: 31 Tier 2, 25 Tier 3, 10 Tier 4, 7 Tier 1 canopy, 2 Tier 1 plant-count, 1 nursery [ocp-adult-use-licensee-search]. Tier expansion should trigger service reviews before energizing new rooms [cmp-mgs-tariff].

Additional load and utility notes

Winter peak at 400 kW on the worked example moves accounts toward Intermediate General Service and large standard offer class [mpuc-cmp-large]. Summer peak near 320 kW shows lighting-only peaks understate winter bills [noaa-cag-maine].

Additional load and utility notes

Versant MPD Rate E-P minimum 50 kW billing demand floor affects small industrial sites in Aroostook [versant-mpd-tariffs]. Do not apply CMP thresholds north of Bangor [versant-mpd-tariffs].

Efficiency Maine before you sign with a CEP

When CMP bills transmission demand per kW, ten peak kW saved beats ten thousand kWh shaved off supply. Efficiency Maine's custom track covers HVAC, dehumidification, and horticultural lighting with engineering analysis and awards up to fifty percent of project cost [efficiency-maine-at-work]. Prescriptive lists cover standard commercial gear, not grow-specific fixtures.

Cross-border checks help benchmark offers. Massachusetts documents Eversource G-2 classes and 935 CMR 500.120 caps; New Hampshire covers three nonprofit ATCs on Eversource GV. CMP and Versant classes sit on the Maine commercial rates page.