A battery earns its capital back in a Mexican plant through one line on the CFE bill, the demand charge. The illustrative figures in this article, MXN 25 million of installed cost against MXN 3 million of annual savings, give a simple payback of 8.3 years. That is the number a plant manager and a CFO should start from, before any tax or financing effect is applied. Everything that shortens it has to be named and quantified.

The regulatory position changed on 7 March 2025. The Comisión Reguladora de Energía published Acuerdo A/113/2024 in the Diario Oficial de la Federación that day, and it took effect the following day. For the first time, a storage system sited at an industrial load center has a defined category in Mexican electricity regulation, along with a registration obligation and a set of limits on what it may do.

This piece sets out the four inputs that decide whether a battery clears a hurdle rate at a Mexican plant. Those are the demand charge as a share of your CFE bill, the installed cost per kWh, the round trip loss, and the tax treatment of the capital. A site with twelve months of billing data can screen the decision in an afternoon.

What a battery does to a CFE industrial bill

Under the CFE tariff schedule, a medium voltage industrial user on GDMTH pays separately for energy and for demand. Demand is not read off a single monthly spike. CFE determines maximum demand from the highest average power drawn during any 15 minute interval, and GDMTH splits the month into base, intermediate and peak periods that vary by region and by season. Capacity charges track the demand recorded in the peak period. Distribution charges track monthly maximum demand.

That structure is what a battery attacks. Charging in the base period and discharging across the peak window lowers the peak period demand reading and the energy price paid for those hours. The saving is a function of how much of the bill sits in demand rather than energy, and of how predictable the peak is. A plant with a flat, continuous load has little to shave. A plant with sharp starts, furnace cycles or shift changes has a great deal.

One correction to a common misreading. Demand charges apply to CFE basic supply industrial tariffs whatever the plant's market status. The 1 MW figure is something else. It is the demand threshold a load center must meet to register as a usuario calificado and buy energy from a qualified supplier. The Secretaría de Energía acuerdo published in the DOF on 1 March 2017 sets that threshold. It stepped the requirement down from 3 MW to 2 MW and then to 1 MW, under the fifteenth transitory article of the Ley de la Industria Eléctrica. A plant below 1 MW still pays demand charges, and a plant that completes the usuario calificado registration process still pays regulated transmission, distribution and capacity charges.

Where the storage rules stood in March 2025

Acuerdo A/113/2024 defines four modalities for a sistema de almacenamiento de energía. The one that matters to a manufacturer is SAE-CC, storage installed at a load center with no generation attached. Under that modality the stored energy serves the load center's own demand. No generation permit is required where the site is supplied by a utility. Injection to the grid is barred where the system participates in wholesale market schemes, and the installation must be registered with the regulator within 90 business days. Storage capacity is also bounded by the contracted demand of the load center.

Read against the rest of the state of energy storage in Mexico, the practical effect is narrow but real. Peak shaving behind the meter is now an authorized use with a defined filing, rather than an activity the rules were silent about. What the acuerdo does not do is create a revenue stream. There is no payment to an industrial battery for capacity or for grid services under this instrument, so the business case still rests entirely on avoided cost.

The worked example, and what its arithmetic says

Take an industrial plant drawing 5 MW at peak, where demand charges account for 30% of total electricity cost. A 2 MW, 4 MWh battery cuts those demand charges by 20%, which produces annual savings of MXN 3 million. The installed cost is MXN 25 million.

Here is the basis for those figures, because the arithmetic has to be shown rather than asserted. This is a modeled illustration built from tariff structure and installed cost assumptions, not a measured result from a completed project. The 30% demand share and the 20% reduction are assumptions, not observations. Taken together they imply a saving equal to 6% of the total electricity bill, which in turn implies an annual bill of MXN 50 million at the site. A reader should check that figure against their own bill before treating the example as representative.

On the payback: MXN 25 million divided by MXN 3 million a year is a simple payback of 8.3 years, not the seven years often quoted for cases of this shape. Simple payback here ignores tax, financing cost, degradation and O&M. The gap between 8.3 years and seven years would have to be closed by after tax and financing effects, and those effects are not quantified in this example. Any shorter figure is only credible when the specific instrument producing it is named and its value shown.

One such instrument does exist. The Decreto por el que se otorgan estímulos fiscales para apoyar la estrategia nacional denominada Plan México was published in the DOF on 21 January 2025. It allows an immediate deduction on investment in new fixed assets acquired from 1 January 2025 to 30 September 2030. The rates are set in the decree by asset class and acquisition period, and the asset must be held for a minimum period. Whether a battery system qualifies, and at what rate, depends on how the asset is classified and is a question for the plant's tax adviser. The effect runs through the after tax cash flows, not through the headline capital number.

Capital cost, degradation and the inputs that move payback

Installed cost is falling fast enough that a quote from two years ago is worthless. BloombergNEF reported on 10 December 2024 that lithium-ion battery pack prices fell 20% during 2024 to a global average of USD 115 per kWh. At system level, BloombergNEF's Energy Storage System Cost Survey 2024 put the global average turnkey price at USD 165 per kWh in 2024, a fall of 40% year on year. The United States average was USD 236 per kWh. Energy-Storage.news reported those figures on 5 February 2025. Mexican delivered pricing sits closer to the United States figure than the global one once import, installation and interconnection work are added.

Two operating assumptions matter as much as the capital number. The National Renewable Energy Laboratory's 2024 Annual Technology Baseline models commercial battery storage on a 15 year life at roughly one cycle a day, with round trip efficiency of 85% and fixed O&M at 2.5% of capital cost a year. Apply those and the picture changes. A 15% round trip loss means the plant buys more kWh than it displaces, and O&M at 2.5% of MXN 25 million is MXN 625,000 a year against MXN 3 million of gross saving.

Lithium-ion systems in industrial service are commonly quoted at 8 to 15 years of calendar life, but calendar life alone is not a modeling input. Ask the supplier for the warranted state of health at year ten and the cycle count that warranty assumes. Payback ranges of 5 to 10 years circulate widely for industrial storage in Mexico, and they hold only under a stated tariff, a stated demand share and a stated installed cost. Quoted without those three, the range tells a CFO nothing.

Backup power is a duration question

A battery is a cleaner alternative to a diesel genset on emissions and on running cost. It is not a substitute on duration. The 4 MWh system in the example, carrying the full 5 MW load of the site, runs for under an hour before it is empty. Sizing for outage ride-through is a separate calculation from sizing for peak shaving, and it starts from the protected load in kW and the hours of protection required. A plant that needs four hours of cover for a 1 MW critical block needs roughly 4 MWh of usable energy for that duty alone.

The emissions claim needs the same discipline. A battery raises total kWh drawn because of the round trip loss. Emissions fall only where the charging window is materially cleaner than the discharge window, or where the battery is charged from onsite solar. Charging overnight from a gas heavy grid and discharging into an evening peak can raise a site's carbon intensity rather than lower it.

What breaks the case

Three things break industrial storage cases in Mexico, and they break them in this order.

Capital cost first. A battery is a lump of capital that competes with production equipment for the same approval. Leasing and third party ownership structures shift that burden, and they also transfer part of the saving to the counterparty. The comparison a board should see is the after tax cash flow of both routes, not the capital number of one against the operating cost of the other.

Degradation second. A system that meets its saving in year one and delivers 80% of it in year eight has a materially longer payback than the simple calculation shows. That is a contractual question. Warranted capacity retention, and the remedy if it is missed, belong in the supply agreement.

Regulation third. Acuerdo A/113/2024 settled the modality question on 7 March 2025, but the wider electricity framework was still being rewritten as this was published, following the constitutional changes to the sector approved in late 2024. Two items carry the most weight for a storage investment. One is whether the registration and interconnection process under the new acuerdo runs to a predictable timetable in practice. The other is whether the treatment of behind the meter storage survives unchanged in the secondary legislation then in preparation.

How to screen your own site

The screening rule is short. Pull twelve months of CFE bills and calculate demand charges as a percentage of the total. Below roughly 20%, a battery sized for peak shaving will struggle to clear a corporate hurdle rate at current installed cost, and the money is better spent on load scheduling and power factor correction. Above 30%, with a peak that is sharp and repeatable, the case is worth modeling properly. Between the two, the answer turns on how much of the peak is genuinely shiftable.

The modeling then needs interval data, not monthly totals. Fifteen minute demand data shows how many kW of peak are actually reducible and for how many minutes at a time, which sets the kW and kWh of the system. An energy audit for a commercial or industrial facility produces both, and it also identifies the cheaper measures that should be exhausted first.

Test the threshold against your own CFE bill

Mexico Energy Partners will review twelve months of CFE bills and, where it is available, 15 minute interval demand data for the site. The output is the demand charge as a share of the bill, the kW of peak that can be shaved, the battery kW and kWh that duty requires, and the simple and after tax payback at current installed cost. Every assumption is listed. You supply the bills and the interval data. We return the screen and the assumptions behind it. This is an assessment of your own data, not a promise of savings or of eligibility for any tax treatment.

Send the files or ask a question at info@mexicoenergypartners.com, or use the form below.

Sources

• Comisión Reguladora de Energía, Acuerdo A/113/2024, Disposiciones administrativas de carácter general para la integración de Sistemas de Almacenamiento de Energía Eléctrica al Sistema Eléctrico Nacional, Diario Oficial de la Federación, 7 March 2025.
• Secretaría de Energía, Acuerdo que establece el concepto de demanda y los requisitos para la agregación de Centros de Carga para ser considerados como Usuarios Calificados, Diario Oficial de la Federación, 1 March 2017.
• Comisión Federal de Electricidad, published tariff schedule for Gran Demanda en Media Tensión Horaria (GDMTH), schedule in force March 2025.
• BloombergNEF, Lithium-Ion Battery Pack Prices See Largest Drop Since 2017, Falling to 115 US dollars per Kilowatt-Hour, 10 December 2024.
• Energy-Storage.news, Behind the numbers, BNEF finds 40% year-on-year drop in BESS costs, 5 February 2025, reporting BloombergNEF Energy Storage System Cost Survey 2024.
• National Renewable Energy Laboratory, 2024 Annual Technology Baseline, Commercial Battery Storage, 2024.
• Diario Oficial de la Federación, Decreto por el que se otorgan estímulos fiscales para apoyar la estrategia nacional denominada Plan México, 21 January 2025.