For many industrial CFOs and Procurement Managers in Mexico, the CFE electricity bill remains a complex and often frustrating line item. In our view, the single most misunderstood cost component within the Gran Demanda en Media Tensión Horaria (GDMTH) tariff is the demand charge. This charge, measured in dollars per kilowatt (/kW), can constitute a substantial portion of monthly energy expenditures. Yet, it is frequently overlooked in favor of a simpler focus on consumption (/kWh). We believe that actively managing peak demand is no longer an operational nuance but a critical financial strategy for achieving significant and sustainable cost reductions.

The Importance of Understanding the GDMTH Tariff

The current economic landscape places immense pressure on Mexico's industrial sector to optimize costs and enhance global competitiveness. Within this environment, energy expenditure represents a primary operational cost and a significant area for potential savings. However, a superficial understanding of the CFE billing structure often leads to missed opportunities.

The GDMTH tariff, applicable to most large-scale industrial users, is intentionally designed to penalize inefficient use of the national grid. It does this by levying heavy charges not just on the amount of electricity consumed, but on the intensity of that consumption at specific times.

This intensity is captured by the "demand charge," which reflects the highest level of power drawn from the grid during defined periods within a billing cycle. A single, 15-minute interval of maximum power usage can set a high-cost benchmark for the entire month, regardless of overall consumption.

For a CFO or Procurement Manager, continuing to view electricity as a simple volumetric commodity is a strategic error. Our analysis demonstrates that failing to control these demand peaks exposes a company to significant and avoidable costs, eroding profitability and creating budget volatility. The urgency, therefore, is to shift from a passive cost-acceptance model to a proactive strategy of demand management.

Deconstructing the GDMTH Tariff

A thorough analysis of a GDMTH bill reveals two primary cost drivers: energy and demand. The energy charge (cargo por energía) is the cost per kilowatt-hour ($/kWh) consumed and varies based on three time-of-use periods: Base (Base), Intermediate (Intermedia), and Peak (Punta). Most cost-reduction efforts traditionally focus here, encouraging consumption shifts to off-peak hours.

However, our analysis shows the demand charge (cargo por demanda facturable) is often the more impactful and less-managed component. This charge is calculated based on the maximum power capacity, measured in kilowatts (kW), required from the grid during the Peak period. Essentially, CFE charges for maintaining the infrastructure necessary to meet your facility's highest potential power draw, even if that peak only occurs for a few minutes a day.

For large industrial operations with energy-intensive equipment such as furnaces, compressors, or large motor arrays, the synchronized startup of these systems can create massive demand spikes, leading to punitive monthly charges that do not correlate with total production volume.

The Disproportionate Financial Impact of Peak Demand

The financial penalty for unmanaged peak demand can be severe. Because the demand charge is highest during the Punta hours (typically early evening on weekdays), any operational spike during this window has a disproportionate effect on the total bill. For many of our clients, we have observed that demand charges can account for anywhere from 30% to over 50% of their total monthly electricity costs. This represents a significant financial vulnerability tied directly to operational patterns.

To illustrate, consider the case of INDUSTRIAX, a client in the automotive manufacturing sector. Before intervention, our analysis of their CFE bills revealed that peak demand charges consistently accounted for over 45% of their total energy expenditure. A short, daily ramp-up in production in the early evening was driving this cost. By strategically reducing the facility's reliance on the grid during peak hours, INDUSTRIAX achieved over MXN 3.6 million in verified annual savings. This highlights that the most significant opportunity for cost reduction lies not in using less energy, but in using it more intelligently.

Peak Shaving with Onsite Generation: A Targeted Solution

The most effective countermeasure to high demand charges is a strategy known as peak shaving. This involves deploying onsite energy resources—typically a solar photovoltaic (PV) system paired with a Battery Energy Storage Solution (BESS)—to supplement or replace grid power during high-cost peak hours. The system is intelligently controlled to discharge stored energy precisely when the facility's demand is highest, effectively "shaving off" the peak that would otherwise be registered by the CFE meter.

When a facility's internal demand begins to ramp up during the Punta period, the BESS automatically injects power into the facility's internal network. This action artificially lowers the amount of power being drawn from the CFE grid. By keeping the grid-measured demand below a predetermined threshold, the demand facturable is significantly reduced, leading to direct and measurable savings on the monthly bill. This transformation turns a volatile operational cost into a predictable and controlled expense, while simultaneously enhancing the facility's energy resilience.

Strategic Recommendations

Based on our extensive analysis and client engagements, we recommend a structured approach for CFOs and Procurement Managers to reclaim control over their energy expenditures. This strategy moves beyond simple energy efficiency to encompass sophisticated demand management. We believe the following steps are critical:

• Conduct a Granular Bill Analysis: Move beyond the total bill amount. Isolate the cargo por demanda facturable and track its percentage contribution to your total costs over 12 months. This will quantify the scale of the financial exposure.
• Correlate Operations with Energy Profiles: Collaborate with your plant and operations managers to align your facility's power demand profile with its production schedules. Identify the specific processes and equipment responsible for creating demand spikes during CFE's Punta period.
• Model the Return on Investment (ROI) of a Peak Shaving Solution: Evaluate the financial case for investing in an onsite solar + storage system. An effective model will calculate the potential reduction in demand charges, factoring in current GDMTH tariffs and projecting a clear payback period and long-term ROI.
• View Onsite Generation as a Strategic Asset: This investment is not merely a cost-cutting tactic but a strategic initiative. Onsite generation improves budget certainty by insulating your operations from tariff volatility, enhances operational resilience against grid outages, and provides a tangible contribution to corporate ESG targets.