Ollin Simulator
Simulate your CFE bill with BESS, using your real data.
First, we rebuild your current bill from CFE, Mexico's state-owned utility, using the same formulas CFE uses, so you can confirm the calculation is exact. Then we calculate the same bill with a battery energy storage system (BESS), month by month, and the total savings the system generates. We email you the result on the same business day.
Step 1 · Your bill data
Enter the data
Tariff (GDMTH) · CFE division · Maximum demand (kW) · Base kWh · Intermediate kWh · Peak kWh · kVArh · Month
Each field comes with an image showing where it appears on the bill. The simulator on this site calculates GDMTH, CFE's medium-voltage hourly tariff for large consumers; if your plant is on DIST or DIT (CFE's subtransmission and transmission tariffs), our platform calculates those tariffs as well: leave us your data and we will send you the result.
Or upload your bill and we will fill it in
If you prefer, upload the PDF or a photo of the bill: we detect the tariff, division, demand, kWh by period, kVArh and month, and show them highlighted on your own bill so you can confirm or correct them. If a field cannot be read, you enter it yourself.
Bill preview with detected fields highlighted and editable.
Step 2 · Your current bill, rebuilt
Your bill says MXN X. Our calculation says MXN X.
We calculate your bill line by line with the tariffs CFE published for your region and your month, and compare it with what you paid. It is the same logic we use to reconcile our clients' savings every month. If it matches, you know the rest of the calculation is reliable; if it does not, we show you which item differs and by how much. The difference may come from adjustments, billing periods or errors: it is worth reviewing with CFE.
Peak energy
kWh in the most expensive window (6-10 pm in winter, Norte). MXN 1.8372/kWh, 85 % more than base.
What a BESS does to it
The BESS discharges here: your plant draws from the batteries, not from CFE. It is the main source of savings.
−87 % in this example
- Fixed charge (supply)
- Fixed monthly fee for having the service. It does not depend on your consumption. The BESS does not change it. No change
- Base energy
- kWh consumed in the cheapest window (overnight). CFE prices it at MXN 0.9908/kWh (Norte, Jul 2026). Rises slightly: the BESS charges its batteries in this window, when energy costs least. +6 % approx.
- Intermediate energy
- kWh in the intermediate window, most of the day. MXN 1.5710/kWh. Practically unchanged; the system prioritizes shifting peak consumption. No change
- Peak energy
- kWh in the most expensive window (6-10 pm in winter, Norte). MXN 1.8372/kWh, 85 % more than base. The BESS discharges here: your plant draws from the batteries, not from CFE. It is the main source of savings. −87 % in this example
- Capacity charge
- Calculated on your billable demand (kW), dominated by your maximum peak demand. MXN 386.37/kW. By shaving peak demand, billable demand drops and this charge with it. −32 % in this example
- Distribution charge
- Calculated on maximum measured demand, with a cap. MXN 72.92/kW. Drops as the maximum demand the meter records goes down. −18 % in this example
- Power factor
- Below 90 %, CFE charges a surcharge; above 90 % it credits you. The Grid Code requires 0.97 from April 2026 for medium-voltage plants of 1 MW or more. The BESS inverter compensates reactive power continuously: the surcharge becomes a credit. From surcharge to credit
- VAT (16 %)
- Applied on the subtotal of all line items. Calculated the same way, on a smaller subtotal. All of ENEGRIN's reconciliation includes VAT, like your bill. Drops with the subtotal
Interactive annotated bill: base / intermediate / peak energy, capacity, distribution, power factor, VAT → calculated total vs. bill total, difference in MXN and %. Each line item explains what it is on hover.
Step 3 · Your bill with BESS
The same bill, with BESS. Month by month.
What you see
- ✓Current bill vs. bill with BESS, by month and by line item
- ✓Estimated annual savings in MXN and as a % of the bill
- ✓Recommended system: power and capacity (kW / kWh), backup hours for your load and approximate equipment footprint
- ✓Assumptions line: assumed load curve, tariff and month used, VAT
- ✓An «add outage backup» switch, and how it changes the proposal
- ✓The total savings the system generates, in MXN and as a % of the bill; how they are split under each model is defined in the proposal
- ✓Both ways to get it, explained: no investment (shared savings) or purchase
What you take away
- ✓A PDF report with your plant's name, in your inbox the same business day
- ✓A shareable link for your director or your finance lead, with an expiry date
- ✓A Spanish version in one click, for your team in Mexico
- ✓«Request a formal proposal»: your simulation reaches our engineering team already complete
Your email is only used to send you the result and, if you ask for it, the proposal.
Estimate calculated with your bills and current CFE tariffs. Once installed, savings are measured with two meters and reconciled every month; the range measured in actual operation is 27–37 %.
Modules on the same engine
Solar + BESS
With your location and your bills: BESS alone or BESS with solar. Which part of the bill each one targets.
Bill audit
Did CFE bill you correctly? A line-by-line check of your bill.
Monthly tracking with your numbers
If you leave your email, each month you receive your simulated bill at that month's tariff: «in September you would have paid MXN X with BESS.» Automatic, and you can cancel with one click.
After the simulator
Request a formal proposal
One click from the result. Our engineering team receives the full simulation and delivers a proposal with both payment models.
Book 20 minutes with an engineer
Online calendar, with your simulation attached.
See our systems in operation
A visit to our systems in Mexico or to the international group's plants, or a live demo of the platform.