On 7 May 2024 the Centro Nacional de Control de Energía declared an Estado Operativo de Emergencia twice in one afternoon, cut up to 2,610 MW of load, and reconnected users over the following three hours. Peak demand that day reached 48,472 MW against net generation of 48,403 MW. That is the profile of a system running without a buffer, and it is the environment every industrial plant in Mexico now budgets in.

The exposure is not confined to emergency days. AMPIP, the association of private industrial parks, found that 91% of Mexican industrial parks experienced failures in energy supply during 2023. For a plant director the question is no longer whether outages happen. It is whether the cost of absorbing them exceeds the cost of an onsite solar and battery system that carries the critical load through them.

This piece sets out why the grid fails and what the published loss figures actually measure. It then shows how to calculate your own site's annual outage cost, and what the March 2025 electricity laws changed for generation and storage behind your meter.

Why the lights go out

Underinvestment in transmission

The Red Nacional de Transmisión has not grown with the load it serves. IMCO, in its September 2024 study on saturation of the electricity networks, reported that national electricity demand rose 3.4% in 2022 and 3.5% in 2023. Transmission network growth in those same years was 0.09% and 0.10%. For 2023, IMCO put CFE's exercised investment at 21.7% of what the Programa de Desarrollo del Sistema Eléctrico Nacional identified as necessary.

Those four numbers are the causal chain. Load grew roughly thirty times faster than the wires. Capacity built in generation-rich regions cannot always reach the industrial corridors that need it, so CENACE curtails generation and interrupts load to hold the system together. Our earlier piece on Mexico's transmission and distribution infrastructure covers how the network is planned and funded.

What pushes the system into emergency

Three pressures act on the same evening hours. Heat drives air conditioning and industrial cooling demand to records. Older thermal plants, including the combined cycle units at Altamira and Villa de Reyes, trip offline without warning. And hydro output has fallen with the drought. Excélsior reported on 11 May 2024 that El Novillo in Sonora stood at 11.2% of capacity and Huites in Sinaloa at 16.4%, against a working minimum of about 25%. The same report cited the International Energy Agency for a 40% annual fall in Mexican hydroelectric generation during 2023.

When the operating reserve margin drops below the 6% threshold for stable operation, CENACE moves to alert and then to emergency, and sheds load. On 7 May 2024 the reserve fell under 3%.

What outages cost, and what the published figures measure

The numbers that exist

Three figures circulate in the Mexican market. Each one is real, and each one measures something narrower than it is usually quoted as measuring.

The Jalisco chambers also reported outages running 3 to 4 times a month, lasting from one minute to three hours, across the Guadalajara industrial corridors. That frequency, not the headline aggregate, is what a site should plan against.

Working out your own number

National aggregates cannot be taken into a capital request. A site figure can. The arithmetic is short.

Start with hours lost. Multiply outage events per year by average duration, then add the restart time your line actually needs, which is usually longer than the outage. Multiply the total by gross margin per production hour, not by revenue. Then add scrapped work in process, overtime to recover the schedule, and any contractual line-stoppage charge in your customer agreements.

An illustration, not a claim. A plant that logs 8 outages a year averaging 90 minutes, with a 60 minute restart each time, loses 20 production hours. At a gross margin of USD 20,000 per production hour that is USD 400,000 a year before scrap and overtime. Run the same calculation with your own three numbers and you have the figure a battery project has to beat.

Costs that never reach the production report

Voltage sags, swells and micro-cortes damage robotics, CNC controls and PLCs cumulatively rather than at once, so the failure shows up months later as a component replacement rather than as an outage cost. Inrush on restart adds to it, which is what staged restart sequencing and soft starters are for. We covered the measurement side in our piece on how power quality events damage industrial equipment.

Process industries lose the batch, not just the hour. In plastics and glass, material solidifies in the wrong place and the line has to be cleared before it can restart. In food and beverage, cold chain excursions turn into scrapped product and diesel fuel cost. Delivery failures under just-in-time supply agreements carry line-stoppage charges whose terms are commercially confidential, so check your own contract rather than a published average.

There is a safety dimension as well. Plants where interior temperatures pass 45 degrees Celsius, or 113 degrees Fahrenheit, without ventilation are not a human resources footnote. They are a stoppage risk in their own right.

Onsite solar

The financial case and the conditions attached to it

Onsite generation displaces grid purchases at the point of consumption. How much of the bill it reaches depends on one ratio that varies by plant: the share of consumption that falls in daylight hours. A three-shift plant and a single-shift plant with identical roofs get very different results, so ask for the figure computed against your metered load curve rather than a percentage range.

Two structures are available. Buy the system and take the tax treatment. Or contract the output under a power purchase agreement at a fixed rate below the CFE tariff with no capital outlay, in which case the developer owns the asset and holds the depreciation.

On tax, the decree of fiscal stimulus published in the Diario Oficial de la Federación on 21 January 2025 allows immediate deduction of investment in new fixed assets. It covers assets acquired between 1 January 2025 and 30 September 2030, at rates set by asset type in the decree, subject to a minimum holding period. Take the applicable rate for your asset class from the decree rather than from a proposal.

The permitting route after March 2025

The Ley del Sector Eléctrico was published in the Diario Oficial de la Federación on 18 March 2025. Under it, generation below 0.7 MW, or 700 kW, is exempt and needs no permit, up from the 0.5 MW threshold of the previous regime. Plants between 0.7 MW and 20 MW built for the owner's own consumption can obtain permits through a simplified procedure from the Comisión Nacional de Energía, and surplus may be sold to CFE, at CFE's discretion.

The practical reading for a plant manager. Sizing a system just under 0.7 MW removes a permitting step and shortens the schedule. Sizing above it is still workable but adds a regulatory path that has to be built into the program. Our overview of the distributed generation route for industrial sites sets out the interconnection steps.

Deacero in Sonora

Deacero contracted the full 110 MW output of a solar plant in Caborca, Sonora, under a 20-year power purchase agreement with IEnova, on a reported investment of USD 115 million. MEXICONOW reported the terms on 27 March 2017. The point for a mid-sized manufacturer is not the scale. It is that a steelmaker fixed the price of a defined block of its electricity for twenty years while grid tariffs moved, and did it through a contract rather than through capital.

Battery storage

Backup power, and exactly what it covers

A battery transfers in milliseconds where a diesel set needs to start, so it holds processes that cannot survive a momentary loss. It does not carry the plant. It carries the load you put on the protected bus, for the duration you paid for.

Specify it accordingly. List the critical loads and each one's ride-through tolerance, decide the outage duration you are insuring against, and size kW and kWh against that list. Backup during a grid failure also needs an islanding capable inverter and a transfer scheme. A system specified only for demand management does not include either. Anything outside the protected bus still drops.

Peak shaving under CFE industrial tariffs

CFE's GDMTH, DIST and DIT tariffs bill energy in kWh and demand in kW, with demand set by the highest recorded consumption in the priced periods. Discharging stored energy through the punta window lowers the demand the meter registers. It reduces the demand charge. It does not eliminate it, because the meter still records a maximum.

The punta block is not the same everywhere. It varies by tariff region and between summer and winter seasons, so read the block for your plant's region and season out of the CFE schedule before setting a dispatch strategy. A battery dispatched against the wrong window earns nothing.

Payback follows from three inputs: the demand charge in pesos per kW for your region, the installed battery cost per kWh, and the cycles per year the strategy actually calls for. Ask for those three numbers written down. A payback claim without them is not a model.

What the March 2025 law does for storage

The Ley del Sector Eléctrico recognizes storage as an activity of the sector and gives the Comisión Nacional de Energía the task of setting how storage integrates into the market and how it is paid for associated services. A storage system may offer energy or a service, and not more than one service type at the same time. For a behind-the-meter installation serving a load center, the practical questions are interconnection and safety compliance, including certification to standards such as UL 9540, rather than a generation permit.

Solar and storage together

How the combined system behaves

During daylight the array serves the plant and charges the battery. In the evening, and during a grid failure, the battery discharges to the protected load. The result is a microgrid whose value comes from two different revenue lines, avoided energy purchases and avoided demand charges, plus an insurance value that only becomes cash on the days the grid fails.

Model the three separately. Adding them into one payback figure is how projects get approved and then underperform.

Grupo Bimbo

Grupo Bimbo has run both routes. Its Piedra Larga wind farm carries 45 turbines and 90 MW of installed capacity supplying the company's Mexican operations. Its Bimbo Solar program reached 3.7 MW across 33 rooftop systems at depots, branches and the corporate campus, according to the company's release of 1 February 2018. Contracted offsite renewables covered the volume. Rooftop generation covered the sites where volume was small and the roof was available.

Comparing the three positions

What to evaluate before the next dry season

The emergency days cluster in the hot months, which means the window to specify, procure and commission runs out well before them. Three steps, in order. Calculate the site outage cost with your own hours and margin. Read the punta block for your region and check what share of your consumption sits in daylight. Then price solar, storage and the combination against those two numbers rather than against a national aggregate.

Mexico Energy Partners runs an onsite power quality and resilience study at no cost. We review twelve months of CFE invoices, the plant single line diagram, the critical load list with each load's ride-through tolerance, and your recorded outage and voltage event log. We return the annual outage cost at that site, the kW and kWh a battery would need to carry the critical load for the duration you specify, and the modeled payback under your own tariff and region. You supply the twelve invoices, the single line diagram and the outage log. A site visit follows if the numbers justify one.

Sources

• Excélsior, "Apagones hoy: Cenace anuncia que opera en estado de emergencia", 7 May 2024, for the emergency declarations, 2,610 MW of load shed, peak demand of 48,472 MW and net generation of 48,403 MW.
• AMPIP, "Los parques industriales como instrumento de desarrollo nacional: Retos en materia energética", reported by Inmobiliare on 19 June 2024, for the finding that 91% of industrial parks experienced energy supply failures during 2023.
• IMCO, "México ante la saturación de las redes eléctricas", 19 September 2024, for demand growth of 3.4 and 3.5%, transmission growth of 0.09 and 0.10%, and CFE investment at 21.7% of the PRODESEN requirement in 2023.
• Excélsior, report on drought and hydroelectric capacity, 11 May 2024, for reservoir levels at El Novillo and Huites and the International Energy Agency figure of a 40% fall in hydroelectric generation in 2023.
• Forbes México, "Maquilas mexicanas pierden 200 mdd cada hora por apagón en norte del país", 16 February 2021, citing Index and its national president Luis Manuel Hernández.
• Consejo de Cámaras Industriales de Jalisco and Cámara de la Industria Alimenticia de Jalisco, reported 30 May 2024, for losses of MXN 200 million to 250 million, about USD 12 million to 15 million. The same reporting gives per-company food sector losses of up to MXN 20 million, about USD 1.2 million.
• Ley del Sector Eléctrico, published in the Diario Oficial de la Federación on 18 March 2025. Read with the summary by Norton Rose Fulbright, March 2025, for the 0.7 MW exemption, the simplified permit route and the treatment of storage.
• Decreto de estímulos fiscales, Diario Oficial de la Federación, 21 January 2025, for immediate deduction of new fixed assets acquired from 1 January 2025 to 30 September 2030.
• MEXICONOW, "IEnova builds US$115 million solar plant in Sonora to supply power for Deacero", 27 March 2017.
• Grupo Bimbo press release on Bimbo Solar, 1 February 2018, for 3.7 MW across 33 rooftop systems and the 90 MW Piedra Larga wind farm.