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, with figures and sources, and the actual date of their last review. CFE is Mexico's state-owned utility; GDMTH is its medium-voltage hourly tariff for large consumers.
Explore a GDMTH bill
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SAMPLE BILL · GDMTH · NORTE DIVISION · JULY 2026Fictitious data
Total for the month$1,063,538
Peak energy
kWh in the most expensive window (6-10 pm in winter, Norte). MXN 1.8372/kWh, 85 % more than base.
What a BESS does to it
The BESS discharges here: your plant draws from the batteries, not from CFE. It is the main source of savings.
−87 % in this example
- 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 energy
- kWh consumed in the cheapest window (overnight). CFE prices it at MXN 0.9908/kWh (Norte, Jul 2026). Rises slightly: the BESS charges its batteries in this window, when energy costs least. +6 % approx.
- Intermediate energy
- kWh in the intermediate window, most of the day. MXN 1.5710/kWh. Practically unchanged; the system prioritizes shifting peak consumption. No change
- Peak energy
- kWh in the most expensive window (6-10 pm in winter, Norte). MXN 1.8372/kWh, 85 % more than base. The BESS discharges here: your plant draws from the batteries, not from CFE. It is the main source of savings. −87 % in this example
- Capacity charge
- Calculated on your billable demand (kW), dominated by your maximum peak demand. MXN 386.37/kW. By shaving peak demand, billable demand drops and this charge with it. −32 % in this example
- Distribution charge
- Calculated on maximum measured demand, with a cap. MXN 72.92/kW. Drops as the maximum demand the meter records goes down. −18 % in this example
- Power factor
- Below 90 %, CFE charges a surcharge; above 90 % it credits you. The Grid Code requires 0.97 from April 2026 for medium-voltage plants of 1 MW or more. The BESS inverter compensates reactive power continuously: the surcharge becomes a credit. From surcharge to 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
Guides
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, measured every five minutes and met at least 95 % of the time each month. Who it applies to: medium-voltage plants with contracted demand of 1 MW or more, and all high-voltage plants. How it is measured.
Behind-the-meter batteries: what changed in 2026
The April 2026 rules issued by the CNE, Mexico's energy regulator: why batteries at your plant do not require a storage permit, which study CENACE, the national grid operator, requires, and which technical standards the system must meet.
BESS, diesel generator or UPS for industrial backup
Which one fits each plant and why, in a single table.
Industrial cogeneration: when it makes sense and which permits it requires
For plants above 1 MW: 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.
Glossary: billable demand, power factor, island mode, BESS, PCS, EMS…
The terms on your bill and in your system, each explained in one sentence.
Blog
- How much does a BESS save a factory on the GDMTH tariff? (with the measured range)
- How to lower the peak demand CFE bills you for
- Power outages at plants in northern Mexico: the real options
- Power factor: what CFE charges on your bill and what the Grid Code has required since April 2026
- Why reported savings and actual savings don't match (and how to avoid it)
- Hybrid gas plant with BESS: why the engines perform better
- Energy in Mexico explained for foreign corporate teams