Tariff
The GDMTH tariff explained: billable demand, capacity charge and peak hours
What each item is, how it is calculated and where it appears on your bill.
Resources
Understand your energy before you hire anyone
Guides written by ENEGRIN engineers on tariffs, cogeneration and industrial batteries (BESS), with figures and sources, and the actual date of their last review. CFE is Mexico’s state-owned utility, and GDMTH is its time-of-use tariff for large medium-voltage consumers.
Explore a GDMTH bill
A GDMTH bill, item by item
Choose a line on your bill to see what it is and what a BESS does to it.
Real bill, GDMTH, Norte Division, January 2026Period Dec 31, 2025 – Jan 31, 2026 · client data removed
Total for the period$8,276,293.65
Exact figures from the CFE bill, in MXN. The printed amount due, $8,276,294.12, includes $0.47 of prior balance.
Peak generation
kWh in the most expensive window (6–10 pm in winter, Norte division). On this bill, MXN 1.7081/kWh: 106% more than base.
What a BESS does to it
The BESS discharges here: the plant draws from the BESS, not from the grid. It is the main source of savings.
Drops · main source of savings
- Fixed charge (supply)
- Fixed monthly fee for having the service. It does not depend on your consumption. The BESS does not change it. No change
- Base generation
- kWh consumed in the cheapest window (overnight). On this bill, MXN 0.8279/kWh. Rises slightly: the BESS charges in this window, when energy costs least. Rises slightly
- Intermediate generation
- kWh in the intermediate window, most of the day. On this bill, MXN 1.4313/kWh. Practically unchanged. The system gives priority to moving consumption out of peak hours. No change
- Peak generation
- kWh in the most expensive window (6–10 pm in winter, Norte division). On this bill, MXN 1.7081/kWh: 106% more than base. The BESS discharges here: the plant draws from the BESS, not from the grid. It is the main source of savings. Drops · main source of savings
- Capacity charge
- Calculated on your billable demand (kW), dominated by your maximum peak demand. On this bill, 5,116 kW × MXN 401.78/kW: 29% of the bill before VAT. By shaving peak demand, billable demand drops and this charge with it. Drops
- Distribution charge
- Calculated on maximum measured demand, with a cap. On this bill, 5,419 kW × MXN 72.92/kW. Drops as the maximum demand the meter records goes down. Drops
- Transmission
- Charge for using the transmission grid, applied to all your kWh: MXN 0.1801/kWh on this bill. Practically unchanged: it is charged on total kWh, and the BESS shifts when you consume, not how much. No change
- CENACE
- Charge for operating the power system (CENACE, Mexico’s grid operator), applied to all your kWh: MXN 0.0076/kWh on this bill. Practically unchanged: it is charged on total kWh. No change
- Ancillary services (SCnMEM)
- Charge for ancillary services not included in the Wholesale Electricity Market, applied to all your kWh: MXN 0.0069/kWh on this bill. Practically unchanged: it is charged on total kWh. No change
- Power factor
- With less than 1 MW of contracted demand, CFE adds a surcharge below 90% and gives you a credit above it. With 1 MW or more, the threshold is 97%. At 95.73%, this bill carries a credit of MXN 14,297.98. Separately, since April 2026 the Grid Code has required 97% (0.97) from medium-voltage plants of 1 MW or more. The BESS inverter compensates reactive power continuously: a surcharge shrinks or turns into a credit, and an existing credit grows. Larger credit
- VAT (16%)
- Applied on the subtotal of all line items. Calculated the same way, on a smaller subtotal. All of ENEGRIN’s reconciliation includes VAT, like your bill. Drops with the subtotal
- Public lighting fee (DAP)
- A municipal levy that CFE collects on the bill. It is not an energy charge. The BESS does not change it. No change
To see the effect on your own bill, upload it to the Ollin Simulator
Guides
Grid Code
Grid Code: the 0.97 power factor required since April 2026
Since April 8, 2026, Mexico’s Grid Code (Energy Regulatory Commission resolution RES/550/2021) has required a power factor between 0.97 lagging and 1.0. It is measured every five minutes and must be met at least 95% of the time each month. It applies to medium-voltage plants with contracted demand of 1 MW or more, and to all high-voltage plants.
Regulation
Behind-the-meter batteries (BESS): what changed in 2026
The April 2026 rules issued by the CNE, Mexico’s energy regulator. Why a BESS at your plant does not require a storage permit if the energy is used only there. Which study CENACE (Mexico’s National Energy Control Center, the grid operator) requires and which technical standards the system must meet.
Comparison
BESS, diesel generator or UPS for industrial backup
Which one fits each plant and why, in a single table.
Cogeneration
Industrial cogeneration: when it makes sense and which permits it requires
For plants with 1 MW of demand or more. When it is cogeneration (steam, hot water or cooling from the engines' heat) and when it is on-site gas-fired generation. Why a hybrid plant with BESS makes sense, and what changed with the CNE’s April 2026 rules.
Contracting
How to choose a BESS provider in Mexico
Four criteria your auditor can check before signing: two-meter measurement, a guarantee on your bill, a clear contract and continuous operation.
Cost
How much does an industrial BESS cost in Mexico?
Under the no-investment model, nothing upfront. What sets the size in kW and kWh, what you pay each month and what is included.
Glossary
Glossary: billable demand, power factor, island mode, BESS, PCS, EMS…
The terms on your bill and in your system, each explained in one or two sentences.