Solar energy for a charging station: how to lower the cost of the kWh

The cost that weighs most on a charging station isn't the charger, which is paid for once. It's the energy, which is paid for at every session. Every kWh the driver takes was bought beforehand, and the difference between the selling price and that cost is the point's margin. Paying the utility's full tariff squeezes that margin. This text shows the three ways to use solar energy at a charging station, what Law 14,300/2022 changed in the math and what to ask before contracting.

Why energy decides the margin

The month's result comes from five numbers: sessions per day, kWh per session, the price per kWh, the cost of energy and the share of whoever operates the platform (the formula is in how much a charging station earns). Of the five, the cost of energy is the only one that multiplies every kWh sold. Lowering it improves all the sessions at once, without touching the price the driver sees.

How the energy credit works

Law 14,300/2022 created the Electric Energy Compensation System (SCEE). In it, the energy generated by distributed micro or minigeneration and injected into the grid is lent to the utility free of charge and later offset against consumption, or kept as a credit (art. 1, XIV).

For the charging station, this solves the timing mismatch. The panels generate during the day, and the charger is also used when there's no sun. With compensation, the energy generated at noon offsets the charger's consumption at ten at night.

The law defines the brackets by the plant's power: microgeneration goes up to 75 kW, and minigeneration, above that, up to 3 MW for non-dispatchable sources like solar (art. 1, XI and XIII).

The three ways to use solar energy

1. Panels on the site itself

The plant goes on the roof or on the parking lot canopy, in the same consumer unit as the charger. It's the most direct form, and the canopy with panels also protects the space from sun and rain. The limit is space. Compare what the available area generates with what the charger should consume in the month: if generation falls below consumption, the panel reduces the purchased portion without covering everything.

2. Remote self-consumption

The plant is at another address, and the credits go to the charging station's unit. The law requires the units to belong to the same legal entity, including headquarters and branch, or to the same individual, and that all be served by the same utility (art. 1, II). It serves those who have a plot of land or another property with space to generate more.

3. Shared generation

Consumers come together in a consortium, cooperative, condominium or other association to split a plant's energy, all served by the same utility (art. 1, X). For the charging station owner, it's the way to have credits without building their own plant: they receive a share of the energy generated and pay for it under the agreed conditions.

At our points we use energy credits from solar generation, with a cost per kWh lower than the utility's tariff.

What Law 14,300 changed in the math

Before the law, compensation offset all the tariff components, a rule that art. 26 preserves for old systems. For new systems, a part of the components tied to the distribution grid (the return on assets, depreciation and the utility's operation and maintenance cost, what the market calls fio B) began to apply to the compensated energy, on a ladder defined in art. 27:

Starting from	Share of distribution components charged on compensated energy
2023	15%
2024	30%
2025	45%
2026	60%
2027	75%
2028	90%
2029	rule defined by ANEEL (art. 17)

Systems that already existed when the law was published, or that requested access to the utility within 12 months of it, stay on the old rules until December 31, 2045 (art. 26). In practice, a new credit is worth less than the full tariff, and the difference grows until 2028. The math of a solar project for a charging station needs to use the year in which it will generate, not the rule from when the law was approved.

Demand, the part the credit doesn't solve on its own

A fast charger can move the property into medium voltage. Under the general rule of ANEEL's REN 1,000/2021 (art. 23), a unit with installed load above 75 kW is connected in Group A. The rule receives updates: the current version applies, which can be checked on ANEEL's website. In that group, the bill has the energy consumed and also the contracted demand, on separate lines. Ask that the solar project's simulation show both, so you don't compare an energy credit with a bill that has another fixed cost alongside it. What changes in the budget with medium voltage is in how much it costs to install a charging station. There's a text on the Velquia blog about how to estimate contracted demand and avoid exceeding it: a charging station's contracted demand, how to calculate it and avoid exceeding it.

What to ask before contracting

• How much does the point consume per month today, or how much should it consume? The solar project comes from that number.
• Are the plant and the charging station served by the same utility?
• Does the simulation use the transition rule for the year in which the plant will generate?
• In shared generation, what is the price per kWh of the credit, for how long and what happens if you want to leave?
• Does the simulation separate energy and contracted demand?
• Who tracks whether the credits are arriving every month on the point's bill?

Those looking for solar to charge their own car at home will find the driver's math in solar energy and electric cars.

Where Elektro Charge comes in

In our network there have already been more than 4,300 charges and more than 100,000 kWh delivered. For those who want to set up their own point, the feasibility consulting analyzes the location, the available power, the cost and the return before you invest. The other questions before buying are in is a charging station worth it?.