A 24/7 automotive components plant in Puebla spending about MXN 3.5 million a month on electricity cut its total electricity cost by roughly 8% over twelve months. That is about MXN 280,000 a month. It bought no equipment to do it. The work was done by the plant's own staff on the equipment already installed.

Three things were wrong, and none of them were consumption. Power factor penalties were recurring because the capacitor bank was poorly maintained and was sometimes left offline after shutdowns. Contracted demand had been set during an earlier expansion and no longer matched the load. Shift patterns had changed the load profile, and the tariff and demand terms had never been revisited.

Any plant director on GDMTH can test whether the same three conditions apply at their own site. It takes twelve months of CFE invoices and the current contracted demand in kW. What that test costs, what it can and cannot show, and where this plant's 8% came from are set out below.

What the plant looked like at the start

Autopartes Puebla runs a continuous operation supplying Tier 1 and OEM customers in North America. Electricity is one of its three largest operating costs. It was treated as a fixed charge, and the finance team's involvement ended at paying on time.

Monthly electricity spend was approximately MXN 3.5 million. The plant billed on GDMTH with pronounced demand peaks. There was no internal energy manager. Invoices were checked for customer name, service address and total amount, and nothing else. Power factor penalties, contracted demand and tariff fit were never reviewed.

That matters because of how the tariff is built. CRE Acuerdo A/158/2024, published in the Diario Oficial de la Federación on 24 January 2025, sets the final basic supply tariffs. GDMTH applies at or above 100 kW per month in medium voltage, charges capacity and distribution on measured kW, and prices energy differently across base, intermediate and peak hours. The same acuerdo carries a power factor provision. A reader who wants the structure in full will find it in our guide to how GDMTH demand charges are calculated.

What the first two billing cycles found

Reviewing two consecutive invoices against the prior twelve months surfaced three recurring items. The capacitor bank was producing power factor penalties month after month, because maintenance was irregular and nobody re-energized it after a planned shutdown. Contracted demand exceeded what the plant actually drew, on assumptions carried over from a previous expansion. The load profile had moved with new shift patterns while the demand and tariff terms stayed where they were.

All three are configuration and operating practice. None of them are kWh. That is the finding worth taking away, because the fix for each one costs almost nothing and none of them appear on a consumption report.

How the subscription ran

The monthly rhythm was fixed. Line by line invoice review covering energy, demand, power factor, penalties and additional charges. Comparison against a 12 month historical baseline to catch anomalies and trends. A short executive summary in Spanish naming what changed, what it cost and two or three actions. A quarterly review with finance and operations covering contracted demand, tariff structure and exposure. Every item was written in pesos and decisions, not in engineering terms.

What the plant changed

The power factor correction equipment was restored, tested and put on a maintenance schedule, with a checklist to be signed after every planned shutdown. Contracted demand was renegotiated with CFE to match the real peak load profile, using data prepared by Mexico Energy Partners. Non-critical loads and cleaning activity were moved out of the peak period to flatten billed demand.

All three were done with internal staff and existing infrastructure. There was no capital project.

The result, and how it was measured

After twelve months, power factor penalties were down by more than 80%. Total electricity cost fell roughly 8%, about MXN 280,000 per month.

Read those two figures as one measurement expressed two ways. MXN 280,000 is 8% of the rounded MXN 3.5 million baseline, so the peso figure is derived from the percentage rather than measured separately.

These are Mexico Energy Partners engagement figures, taken from the client's CFE invoices under a non-disclosure agreement. They have not been audited by a third party. Four things about the basis are worth stating plainly.

• The three-way split has not been published. How much of the MXN 280,000 came from eliminated power factor penalties, how much from the lower contracted demand charge and how much from moving load out of peak is held in the engagement file and is not in this article.
• The three components are not the same quality of number. A removed penalty is cash. A lower demand charge holds only while metered demand stays under the new contracted level. Moving load between tariff periods cuts the billed demand charge without cutting a single kWh, so it changes the bill and not the consumption.
• Tariff movement over the twelve months was not netted out of the headline figure. CFE tariffs are reset periodically, so part of any year on year change belongs to the tariff and not to the plant.
• Plant output was not normalized. INEGI reported on 7 October 2025 that Mexico produced 355,525 light vehicles in September 2025, down 6.1% year on year, with 3,021,554 units in January to September 2025 and a variation of 0.3% below the same period of 2024. National output was close to flat over that stretch and negative in the most recent month, which is exactly why a plant level result should be checked against the plant's own production before it is credited to the program.

The subscription fee is not disclosed here, so the statement that savings exceeded the fee within the first month cannot be checked by a reader. Ask for the fee and run the division yourself.

The risk in a lower contracted demand

Reducing contracted demand narrows the headroom before demand overruns start being billed. If the plant adds a shift, commissions a new line or restarts equipment after a long outage, metered demand can pass the new contracted level and the charge follows. The headroom left at this plant, the time CFE took to process the change and whether the change can be reversed on short notice are not stated in this case. They are the first questions to ask before copying the action.

Which plants are likely to find the same thing

This is one site. It had an unmaintained capacitor bank and a contracted demand left over from an expansion. A plant without those two conditions will not find 8%, and this case should not be read as a sector result.

The preconditions are testable. Billing on GDMTH. A capacitor bank with no maintenance record or no restart procedure after shutdowns. A contracted demand figure that predates the last production change. No monthly review of the invoice beyond the total. Where several of those hold, there is usually something in the bill.

The range across automotive sites is wide. A Querétaro auto supplier that cut its CFE bill by 28% started from a different set of conditions, and the gap between 8 and 28 is the reason to measure your own site rather than to budget from someone else's result.

The lasting change at this plant was not the billing fix. It was that electricity entered the monthly cost review alongside materials and labor, and that the budget is now built from twelve months of validated invoice data rather than from last year plus an inflation assumption.

Have your last twelve CFE invoices reviewed

Request an invoice review. Send twelve months of CFE invoices for one site, the current contracted demand in kW, and the tariff shown on the bill.

Mexico Energy Partners will return a written review covering power factor penalties, contracted demand headroom and tariff fit, with the peso value of each item and what correcting it would involve. The review states what is recoverable and what is not. It is not a promise of savings, of a tariff change or of a successful renegotiation with CFE.

Sources

• Comisión Reguladora de Energía, Acuerdo A/158/2024, published in the Diario Oficial de la Federación on 24 January 2025. GDMTH threshold of 100 kW per month in medium voltage, capacity and distribution charges on measured kW, base, intermediate and peak energy periods, and the power factor provision.
• INEGI, Registro Administrativo de la Industria Automotriz de Vehículos Ligeros, monthly report released 7 October 2025. Light vehicle production of 355,525 units in September 2025, down 6.1% year on year, and 3,021,554 units in January to September 2025.
• Mexico Energy Partners engagement file for this client. Baseline and result invoice data, power factor penalty reduction and the cost figures. Held under a non-disclosure agreement and not independently audited.

Service: BillGuard & Tarifa. Sector: Automotive components manufacturing. Note: The company name, Autopartes Puebla, has been changed in accordance with our non-disclosure agreement.