A hotel on CFE's GDMTO or GDMTH tariff buys two things on the same invoice. It buys energy, measured in kWh. It also buys demand, measured in kW, set by the highest load the property registers during the month. Rooftop solar cuts the first. On its own it does very little to the second.

That split decides how much of a Mexican hotel's electricity cost is actually reachable. It is also why properties sign a solar power purchase agreement and then find the saving on the invoice is smaller than the one in the proposal. The question an owner or finance director has to answer is not whether to buy solar. It is the order of spend: load control first, then generation, then storage.

What follows answers the questions Mexico Energy Partners is asked most often by hotel and resort operators in Mexico. Tariff levels, regulations and tax provisions are stated as of June 2025.

What moved in CFE tariffs

Why hotel energy cost moved up the agenda

Energy21 reported on 16 January 2025 that CFE raised January 2025 rates for industrial and large commercial users on the GDMTH, DIST and DIT tariffs by 12%, the steepest single step in five years. The same report put increases between September 2023 and September 2024 at 3.39 to 3.89%, varying by region and hour block. A 12% move in one month is a budget problem, not a sustainability topic.

The mechanism matters as much as the number. Basic supply tariffs are not fixed once a year and then escalated. The Comisión Reguladora de Energía sets the calculation and adjustment methodology, and final basic supply tariffs are published on a monthly cycle. The rate a hotel pays therefore tracks fuel and network costs month by month. On the engagements Mexico Energy Partners has run, budgeting the coming year against last year's average rate is the most common planning error.

Where the electricity goes in a large hotel

Air conditioning, lighting, domestic hot water and kitchen refrigeration account for most of a resort's electricity. Air conditioning normally leads at coastal and low altitude properties because it runs all year and follows occupancy and outdoor temperature at once.

The useful split is not by equipment type. It is between load you can move in time and load you cannot. Laundry, pool filtration, irrigation pumping and some kitchen preparation can be scheduled. Guest room air conditioning and refrigeration cannot. Establish that division before any equipment is specified. Our earlier brief on energy efficiency in Mexico's hospitality sector sets out the audit sequence.

How GDMTO and GDMTH change what you can save

Both are medium voltage tariffs. CFE's published tariff schedules apply GDMTH to medium voltage services with contracted demand above 100 kW, and GDMTO below that. Maximum demand is measured in 15 minute intervals. One interval can set the demand charge for the whole month, occupancy or not.

GDMTO carries a single energy price plus a charge on billed demand. GDMTH prices energy separately in the base, intermediate and punta periods and sets billed demand from the maximum demands measured in those periods. Two operating decisions follow. Move schedulable load out of the punta window, and hold a demand ceiling that a supervisor is accountable for. A laundry started at 19:00 in a summer punta window can cost several times the same cycle run at 04:00.

Neither decision requires capital. Both change the invoice in the next billing cycle. That is the reason to sequence them ahead of a generation project.

Upgrades that change a resort's load curve

Trigeneration

A combined cooling, heat and power plant burns gas onsite to make electricity, then recovers the waste heat for domestic hot water and for an absorption chiller that produces chilled water. It pays only where three conditions hold together. The property needs year round simultaneous demand for power, hot water and cooling. It needs firm gas supply at the site. And it needs a spread between the gas price and the delivered electricity price wide enough to cover the plant and its maintenance. Where any one of those fails, the economics fail with it. Run the spark spread against a full year of CFE invoices and a gas quotation before ordering equipment.

Seawater cooling

Deep seawater cooling replaces mechanical chilling with cold water drawn from depth through a heat exchanger. The World Bank, in a 24 July 2024 analysis of seawater air conditioning in the Caribbean, put the reduction in cooling electricity at up to 90% against conventional chillers, with project estimates in the range of 83 to 94.5%. Warm return water can preheat pools.

The gate is capital cost and site geography, not efficiency. The same World Bank analysis cites 16.5 million USD for 854 tons of cooling at Runaway Bay in Jamaica and 70 million USD for 7,100 tons at Pedernales in the Dominican Republic, with intake pipelines running to roughly 900 meters of depth. A single property rarely carries that. The structure that works is a district loop shared across several properties, which makes it a destination level decision rather than a hotel level one.

Water reuse and irrigation

Onsite treatment lets a resort irrigate gardens and golf courses with treated effluent instead of potable supply, and cuts both the water bill and the pumping energy behind it. An EarthCheck case study on Grupo Vidanta distributed by the Pacific Asia Travel Association, covering benchmarking years 2004 to 2010, records an onsite treatment plant with treated water reused for garden and golf course irrigation and reports avoided potable water cost of 1,338,795 pesos.

Two Mexican requirements govern the design and are often missed at concept stage. Discharge to a national water body or to a municipal system requires a CONAGUA permit under trámite CONAGUA-01-001. Reuse of treated water in public services, which includes landscape irrigation where people have direct or indirect contact, is governed by NOM-003-SEMARNAT-1997 and its limits on coliforms, helminth eggs, fats and settleable solids. Design the plant to the reuse standard you intend to claim, not to the discharge standard.

Sensor driven irrigation is the cheaper half of the same problem. Soil moisture probes and evapotranspiration data, cross referenced against local weather, stop the system watering ahead of rain and cut both water volume and pump run hours.

Variable frequency drives on pumps

A large resort can run dozens of pumps continuously for pools, fountains, water features and irrigation. A drive lets a pool pump run at full speed during guest hours and at 40 to 50% overnight for filtration. Under the pump affinity laws, shaft power falls with the cube of speed, so halving speed can cut consumption by around 80%.

That figure holds only where the system curve is dominated by friction. Pools, fountains and irrigation lines with lift carry static head, and where static head dominates the cube relationship breaks down and the saving is far smaller. Two retrofit issues also belong in the scope. Drives inject harmonics that a property with sensitive electronics may have to filter, and drive fed motors can need shaft grounding to control bearing currents.

Solar PPAs and batteries

What a power purchase agreement covers

Under the Mexico Energy Partners model, MEP or its partners fund the design, procurement and installation of the rooftop system. The hotel puts up no capital, buys the output under a contract of 10, 15 or 20 years at a fixed rate, and MEP operates and maintains the plant. Terms and structures vary by developer, and our questions and answers on how PPAs are structured in Mexico covers the variants.

State the comparison precisely. The PPA rate is quoted against the CFE energy charge, and it can run up to 50% below it. It is not a discount on the whole invoice. A rooftop array generates in daylight hours only, so it reaches daytime kWh, and it does not by itself reduce billed demand. Ask any developer for two numbers before signing: the share of your annual kWh the array will supply against your metered load curve, and the effect on billed demand in each period.

Rooftop capacity is not unlimited either. The distributed generation route set out by the CRE in Resolución RES/142/2017, published in the Diario Oficial de la Federación on 7 March 2017, covers plants under 0.5 MW and defines the net metering, net billing and total sale contracts. A large resort's load usually exceeds what 0.5 MW of rooftop can serve, which pushes part of the supply question to offsite contracting.

The market is not marginal. Energía Estratégica reported on 5 February 2025 that Mexico added 1,086.22 MW of distributed generation across 106,934 interconnection contracts during 2024, taking the installed total to 4,447.92 MW, of which solar photovoltaic is 99.4%.

What a battery does and does not do

A battery energy storage system stores electricity from the array or from the grid in low priced hours and discharges it later. Two applications are worth modeling for a hotel. Discharging into the punta window lowers the demand peak the tariff bills, and storing midday solar output for evening use raises self consumption when the evening load is highest and generation is zero.

Two claims about batteries need care. Backup power during a grid outage is not automatic. It requires an islanding capable inverter, a transfer scheme and energy sized against the critical load and the outage duration you plan for, none of which is included in a system specified for demand management. And whether a backup or associated services obligation applies to an intermittent generator depends on how the plant interconnects. A plant under 0.5 MW sits inside the RES/142/2017 distributed generation contracts. Larger onsite plants interconnect on other terms, and the obligation has to be read off the actual interconnection contract. Fix the interconnection route before you size the battery on a compliance argument.

Tax treatment

How the Article 34 deduction works

Article 34, fracción XIII of the Ley del Impuesto Sobre la Renta sets a 100% deduction rate in the year of investment for machinery and equipment used to generate energy from renewable sources or through efficient electricity cogeneration. The provision carries a condition that is frequently left out of proposals. The assets must remain in operation for a minimum of five years following the year in which the deduction is taken. If they do not, the taxpayer pays ISR on the difference between the 100% taken and the ordinary depreciation that would otherwise have applied.

The deduction belongs to whoever owns the asset. Under a power purchase agreement the hotel does not own the equipment, so the depreciation benefit sits with the developer rather than with the property. That is a real difference between a PPA and an owned system, and it belongs in the comparison alongside the capital outlay. Ask for both cases priced.

State and municipal programs

Several Mexican states run incentives for sustainability investment, in forms that have included property tax and payroll tax relief and preferential credit lines. Terms differ by state and by year, and programs open and close without much notice. Mexico Energy Partners does not maintain a public state by state list for that reason. Obtain the governing state decree or published guideline, confirm the window is open, and only then put the amount in a model.

What to do with this

The sequence is the takeaway. Meter the property and separate shiftable from non shiftable load. Move what can move out of the punta window and set a demand ceiling someone owns. Then price generation against the load curve that remains, and only then decide whether storage earns its capital. Reversing that order is what produces the gap between a proposal and an invoice.

Talk to Mexico Energy Partners about your property

Mexico Energy Partners reviews hotel and resort energy positions in Mexico. Our work with owners and operators is set out on our hotel and resort practice page.

Send twelve consecutive CFE invoices, your tariff class, room count, and the roof and parking area available. We will return the split of your bill between energy and demand charges, an estimate of the share of annual consumption a rooftop array could supply against your load pattern, and what is left for load shifting or storage to address. If you are weighing a PPA against ownership, we will show both, including where the Article 34 deduction sits in each case. A site visit follows if the numbers justify one. We do not quote a saving before we have seen the invoices.

Sources

• Energy21, "CFE aumenta 12% tarifas eléctricas para sector industrial", 16 January 2025.
• Comisión Federal de Electricidad, published tariff schedules for Gran Demanda en Media Tensión Ordinaria and Horaria, consulted June 2025.
• Comisión Reguladora de Energía, Resolución RES/142/2017, disposiciones administrativas de carácter general and model contracts for distributed generation plants under 0.5 MW, Diario Oficial de la Federación, 7 March 2017.
• Ley del Impuesto Sobre la Renta, Article 34, fracción XIII, deduction rate for machinery and equipment for renewable generation and efficient cogeneration, text in force at June 2025.
• World Bank, blog analysis of seawater air-conditioning solutions for the Caribbean, by Jonathan Coony and Rochelle Simone Johnson, 24 July 2024.
• Energía Estratégica, 2024 distributed generation installation figures for Mexico, reported 5 February 2025.
• EarthCheck case study on Grupo Vidanta, Pacific Asia Travel Association sustainability case series, benchmarking years 2004 to 2010.
• NORMA Oficial Mexicana NOM-003-SEMARNAT-1997, limits for treated wastewater reused in public services.
• Comisión Nacional del Agua, trámite CONAGUA-01-001, permiso de descarga de aguas residuales.