What Mexico City's solar push changes for a facility inside the city
If you run a plant, warehouse or commercial building in Mexico City, two local instruments bear on your capital plan and neither appears in a CFE tariff review. The first is Ciudad Solar, the city government's energy sustainability strategy, which has already put money onto industrial rooftops in the Vallejo corridor. The second is an environmental norm that turns solar water heating into a permit condition for certain buildings rather than a choice. The decision they force is whether a CDMX site should size rooftop solar for the city program or for the federal interconnection rules, because the two point in different directions.
Federal rules still govern what you can connect. A rooftop array in CDMX is generación distribuida under CRE's framework, and the line that decides whether you file an interconnection request or apply for a generation permit is 0.5 MW of generating capacity. We take that threshold to shape how a multi-building site phases an installation far more than any city grant does.
What Ciudad Solar has funded, in pesos
Energía Hoy reported on 10 November 2021 that total investment in Ciudad Solar had reached MXN 1,700 million, of which MXN 1,300 million had gone into the Vallejo industrial zone, according to Fadlala Akabani, the city's secretary of economic development. The flagship installation is an 18 MW rooftop photovoltaic plant spread across 40 industrial units at the Central de Abastos, at a reported cost of a little over MXN 400 million. The same report put the expected reduction at about 13,000 tonnes of CO2 a year.
Every figure in that paragraph is in Mexican pesos. Amounts for this program also circulate as US dollar equivalents, and at the exchange rates of the period the two differ by roughly twenty times. Check the currency before any of these numbers reaches a board paper.
The Vallejo figure is the one to notice. The city concentrated its industrial rooftop spending in an existing industrial corridor rather than in new development. A facility already in Vallejo or at the Central de Abastos sits inside the program's demonstrated footprint. A facility elsewhere in the city does not, and should treat any CDMX contribution as unfunded until confirmed with SEDECO in writing.
The 18 MW that is really forty systems
Eighteen megawatts across 40 industrial units averages 450 kW per unit. That is our arithmetic on published figures rather than a design CFE has confirmed, and it lands just under a line that governs every rooftop in the country. Generación distribuida covers Centrales Eléctricas with capacity below 0.5 MW, under SENER's Manual de Interconexión de Centrales de Generación con Capacidad menor a 0.5 MW (DOF, 15 December 2016) and CRE's Resolución RES/142/2017 (DOF, 7 March 2017). Below the line, the route is an interconnection contract handled by CFE Distribución. Above it, the project needs a CRE generation permit and a different set of obligations.
The threshold applies to generating capacity, not to the facility's load, and it is written in MW rather than in kWp of DC panel. Two things follow for a multi-building campus. What is measured is the capacity of each Central Eléctrica at its own interconnection point, so phasing across buildings is a legitimate design decision rather than a dodge. And a system quoted at 520 kWp DC with an inverter rating below 0.5 MW is a different filing from one quoted at 520 kW AC. Get the AC number in the proposal.
Choose the settlement modality with the same care. RES/142/2017 sets out three. Medición neta credits surplus generation against future consumption for up to twelve months. Facturación neta meters and values generation and consumption separately. Venta total sells all output at the Precio Marginal Local. Migration between them is allowed only after a year of operation, so the choice made at interconnection is a twelve-month commitment. For a plant whose load runs through daylight hours, medición neta is the usual default, and calling it a sale of power to CFE is wrong. It credits energy. It does not purchase it.
The water heating norm that catches commercial buildings
NADF-008-AMBT-2017, the CDMX environmental norm on the use of solar energy for water heating in buildings, installations and establishments, was published in the Gaceta Oficial de la Ciudad de México on 14 November 2018. It applies to new construction and total remodeling of all residential buildings, all pools using hot water, and all establishments with more than 30 users consuming hot water. The required solar fraction varies by building type. Residential buildings of one to four floors must reach 70%. Private commercial and service establishments above the 30-user threshold must reach 35%. Public administration buildings must reach 40%.
Read the establishment trigger again, because it is a headcount of hot water users rather than a floor area or a connected load. A plant with locker rooms and showers serving a shift of more than 30 people, going through a total remodel, is inside the norm. This is the CDMX requirement most often discovered at plan review, and designing for it costs less than retrofitting around it. It is also the cheapest available evidence for a green building certification file, since the norm compels documentation that a certification submission would otherwise have to generate.
Where the city's money came from
Mexico City was the first local government in Latin America to issue a green bond, in December 2016, for MXN 1,000 million (Climate Bonds Initiative). Proceeds financed public transport including the Metrobús Line 5 corridor and light rail, energy efficiency in public street lighting, and water supply and treatment. The instrument matters here less for what it built than for the reporting obligations attached to it. Those obligations are why CDMX program figures are published at all, and why they can be checked against a source rather than taken from a press release.
The city also converts used cooking oil into biodiesel with the Instituto Politécnico Nacional to fuel part of its public transport fleet. Output figures for that program that appear in secondary coverage are not reconcilable with one another, differing by more than a factor of eleven, so no volume is stated here.
Before capital is committed in CDMX
- Whether the site falls inside the Vallejo or Central de Abastos footprint where city funds have actually been deployed, confirmed with SEDECO rather than assumed from program literature.
- The AC rating of each proposed Central Eléctrica against the 0.5 MW threshold, measured per interconnection point rather than per campus.
- Which RES/142/2017 modality the interconnection contract names, and the twelve-month lock before migration is permitted.
- Whether any planned new build or total remodel triggers NADF-008-AMBT-2017, and which solar fraction applies to that building type.
- The delivered cost against a qualified supply contract, including porteo, the transmission and distribution wheeling charges that a behind-the-meter rooftop avoids and a remote contract does not.
Any savings percentage a developer quotes for a CDMX rooftop is measured against current CFE supply and moves with tariff class, region, load factor and consumption profile. Treat it as illustrative until it has been rebuilt from interval data and 12 months of billing for the specific meter. Where a site has no interval data, that is the first gap to close, and it is a metering exercise rather than a study.
Sizing a CDMX rooftop against the rules that actually bind
Mexico Energy Partners reviews rooftop solar sizing, interconnection route and settlement modality for facilities in Mexico City, and compares the result against qualified supply pricing on a delivered basis. An initial review needs 12 months of CFE bills, the tariff class, the available roof area by building, and the single-line diagram.
Request a distributed generation review