Important message

On July 10, 2020, Hydro‑Québec filed an application with the Régie de l’énergie to expand the eligibility rules applying to the Additional Electricity Option for photosynthetic lighting. The power demand threshold would decrease from 300 kilowatts (kW) to 50 kW, electricity consumption for space heating to raise crops would qualify as well as that used for photosynthetic lighting, and Rate LG customers would also become eligible. The Régie’s decision is expected in the coming months.

Read the press release

This rate option is designed for greenhouse operators who use all or part of the electricity supplied by Hydro‑Québec for photosynthetic lighting. More specifically, it targets customers who are able to adjust their production and to manage their electricity consumption in such a way as to reap the benefits of the Additional Electricity Option while working with the associated constraints.

This option applies to a Rate DP, M or G9 contract where some or all of the electricity is used, in whole or in part, for photosynthetic lighting and the maximum power demand has been at least 300 kilowatts (kW) during a consumption period included in the 12 consecutive monthly periods preceding the date of the sign-up request.


The price applicable to additional electricity, which covers both power and energy, varies month to month and is based on Hydro‑Québec Distribution’s marginal supply costs. It cannot be lower than 5.59¢ per kilowatthour when the option is applied to a Rate DP, M or G9 contract.

Depending on load management requirements and power system availability, Hydro‑Québec reserves the right to prohibit consumption of additional electricity on two hours’ notice.

Hydro‑Québec will notify you of the price of additional electricity seven business days before the beginning of each calendar month. This price will remain fixed for the entire monthly period.

Calculation of billing amount

Energy billed as additional electricity is calculated in 15-minute blocks.

  • Consumption that exceeds the reference power is billed at the applicable price for additional electricity.
  • The reference power and corresponding energy are billed at the prices and conditions in effect for Rate DP, M or G9.

How to sign up for this rate option

You must submit your initial written request to Hydro‑Québec at least 15 business days before the start of the first consumption period for which you would like to avail yourself of the option.

Subject to installation of the appropriate metering equipment, agreement on the reference power and Hydro‑Québec’s written approval, the option takes effect at the beginning of the consumption period following the period during which Hydro‑Québec receives your written request.

Thereafter, you must submit a written request to Hydro‑Québec at least five business days before the start of any consumption period to which you would like the option to apply.

For more information

If you have any questions about this rate option, contact your commercial officer or designated agent. You can also reach our Business customer services by phone at 1 800 463-99001 800 463-9900 or by email at

This information has been simplified. For more details about the Additional Electricity Option for photosynthetic lighting available to business customers, consult the following sections of the Electricity Rates, approved by the Régie de l'énergie:

Maximum power demand

Maximum power measured during a consumption period. It is the higher of the following two values: real power in kilowatts (kW), or a percentage (90% for domestic rates and small- and medium-power rates, or 95% for large-power rates) of the apparent power in kilovoltamperes (kVA).


Total amount of electricity supplied at a given time. Expressed in kilowatts (kW), power is the combined effect of voltage, expressed in kilovolts (kV), and current, expressed in amperes (A).


Power used by electrical equipment over a given period of time. Expressed in kilowatthours (kWh), energy is calculated as power, expressed in kilowatts (kW), multiplied by the time during which the power is used, expressed in hours (h).

Minimum price of additional electricity

The price of additional electricity cannot be lower than an average price, expressed in cents per kilowatthour.

  • The reference power and corresponding energy consumption are billed at the prices and conditions in effect for Rate DP, M or G9.
  • All excess consumption is billed at the applicable rate for additional electricity.

Reference power

The reference power must reflect the customer’s normal consumption at Rate DP, M or G9. It is expressed in kilowatts (kW).

Consumption period

Period during which electricity is delivered to the customer and which extends between the two dates used by Hydro-Québec for calculation of the bill.