Methodology

How we calculate.
No promises.

Asolea reads CFE bills and estimates whether solar panels could pay off for you. This page explains where its numbers come from and what they leave out. It is a first opinion: not a quote, a promise of savings or a CFE document.

How we read your bill

An AI (Google's Gemini) reads the photo or PDF and extracts the tariff, usage, period, charges and history. Our code then validates that data and does all the math: the AI does not calculate your savings. We show how much data we found and what we could not read, because automatic reading can make mistakes. Always check the data against your bill.

How we estimate your savings

On home tariffs, the price of each kWh depends on how much you use, so one bill says little about the year. That's why we bill each period in your history with and without panels, step by step, so the same home gets almost the same result from any of its bills.

We assume net metering (medición neta): what is left over in one period stays as a credit for up to 12 months.
We respect the 25 kWh monthly minimum charged to homes.
The fixed charge, street lighting and past-due amounts stay: panels don't lower them.
On tariffs 1A to 1F we use the official summer and non-summer steps, and assume your summer runs from May to October, because CFE sets it by town.
If the bill has no history, we assume the whole year looks like that period, and we say so.
For businesses we count energy only. We don't count a drop in demand or capacity charges, because in most of Mexico peak hours fall at dusk.

How we suggest a size

We start from covering up to 85% of your yearly usage, with 550 W reference panels and 80% overall performance. On home tariffs we stop adding panels when one more would take over 10 years to pay off, because the last kWh it removes are the cheapest.

The sun in your area comes from NASA POWER, a regional average with a resolution of about 1°. It doesn't measure your roof, shade or orientation. Without a location we use 5 hours of sun a day for reference.

How we estimate cost

We use $18,000 to $24,000 pesos per installed kWp. This is a cautious assumption, a little above the commercial ranges published in 2026, so as not to over-promise. It is not a quote: the real price depends on scope, roof and equipment.

How the score works

The score runs from 0 to 100. Up to 75 points come from simple payback in the cautious scenario: 5 years or less gives 75; 6 years, 65; 8 years, 58; 10 years, 50; 12 years, 35; 15 years, 20; and over 15 years, 0. Up to 25 points come from the tariff: DAC gives 25, business tariffs 20, PDBT 18, and in a subsidized home it depends on how much of your yearly usage falls in the excess step. 75 to 100 is high potential, 55 to 74 medium and 0 to 54 low. If data is missing, we don't give a number.

What we don't count yet

Panel wear, maintenance and inverter replacement, which reduce long-term savings.
Shade, orientation and the condition of your roof.
Seasonal changes in production: we spread it evenly across the year.
Leaving DAC, which we show separately because the bill doesn't say which tariff you would have afterward.

Where the prices come from

We prefer the price printed on your bill. What a bill doesn't show comes from these sources, and the report says when it uses them.

Each guide cites its own sources. If you find a mistake or an outdated figure, write to us at [email protected].

Last reviewed: November 3, 2026.

How we calculate.No promises.