Before quoting solar panels, the first thing you need is to understand your CFE bill. That sheet contains all the info needed to size your solar system correctly. Here’s what to look for.

Key data on your CFE bill

  • Tariff: 1A, 1B, 1C, 1D, 1E, 1F or DAC. Indicates your climate zone.
  • Billing period: exact bimester. Note it.
  • kWh consumed: the most important data. This is what we’ll replace with solar.
  • Total due: your bimonthly cost.
  • Consumption history: chart of recent bimesters. Indicates your yearly pattern.
  • Average kWh per day: appears in the details section.

The basic calculation

To size your system you need your annual total kWh consumption:

  1. Add the kWh from your last 6 bimonthly bills (full year).
  2. Divide by 12 for your monthly average.
  3. Divide by month days and your zone’s peak sun hours (Mexicali: 6.5, Tijuana: 5.4).
  4. Result is the kWp solar system you need.

Real example in Mexicali

Family with bimonthly readings: 950, 1,180, 1,420, 1,520, 1,100, 980 kWh. Annual total = 7,150 kWh. Monthly avg = 596 kWh. Math: 596 / 30 / 6.5 ≈ 3.05 kWp → 7 panels of 440W, or round up to 8 panels for margin.

Other factors to consider

  • Future growth: planning another AC unit or electric car? Each adds 1,500-3,000 kWh annually. Size 20% bigger.
  • Real losses: panels produce ~85% of nameplate capacity in real-world operation. Add 15% to the calculation.
  • CFE tariff inflation: rates rise ~5% annually. Doubles in ~10 years. Bigger system today preserves absolute savings tomorrow.

The #1 sizing error

Sizing on the lowest-bill month. In Mexicali, May-October bills are 3-5x higher than January-March. If you size on winter, your system falls short in summer (when you need it most).

Don’t have the last 12 months?

No worries. If you only have the last 3 bills, identify if they’re peak or off-season and project the missing ones. At I-Vert we do this analysis free: send us your bills and we deliver the ideal system in less than 24 hours.

Conclusion

Your CFE bill is the raw material for designing your solar system. Learning to read it helps you understand how much you can save and prevents being sold a system that’s too big or too small.