Net metering & Fio B — Law 14,300

How the SCEE works

The Sistema de Compensação de Energia Elétrica (SCEE, Electricity Net-Metering System) is the framework under which active energy injected into the grid by a consumer unit with MMGD is provided as a free loan and then offset against consumption or recorded as a credit (art. 1, XIV). ANEEL (Brazil's electricity regulator) describes the same mechanism on its Distributed Microgeneration and Minigeneration page.

• Credits in kWh. A credit is surplus not offset in the cycle in which it was generated and is recorded for later cycles (art. 1, VI). It is an active-energy quantity and does not change with movements in the R$ tariff (art. 13, § 1).
• Validity: 60 months. Confirmed: credits expire 60 months after the billing date on which they were generated (art. 13, caput). They then revert to tariff moderation, without compensation to the consumer.
• Offset. The oldest credits are always used first (art. 13, § 2). The model — local, autoconsumo remoto (remote self-consumption), geração compartilhada (shared generation), or EMUC — determines where the offset occurs.

What the market calls “fio B”

The statute does not say “fio B.” Art. 27 applies increasing percentages, on compensated active electrical energy, to components related to remuneration of distribution assets, the regulatory reintegration quota (depreciation), and distribution-service operating and maintenance costs. In industry terminology, this block is TUSD “fio B.” General tariff composition: ANEEL — Understanding the tariff.

Confirmed schedule (art. 27)

For units not covered by art. 26. Percentage of the components above, on compensated energy:

From 2029. Art. 27, VII refers to the rule in art. 17: SCEE units are subject to tariff rules established by ANEEL, with valuation of costs and benefits (CNPE guidelines; ANEEL calculations — art. 17, §§ 1–2). Gap: the statute does not set a “100% of fio B + TE” formula for 2029; the regulation contemplated in art. 17 determines the valuation.

“Instantaneous” self-consumption. Art. 27 applies to compensatedactive energy. Energy generated and consumed at the same instant at the consumer unit is neither injected nor compensated, so the percentage does not apply. The statute does not use the word “instantaneous”; the result follows from art. 27's main provision and the definitions of surplus and credit.

Mini-calculator · 2026 = 60%

Apply the current percentage under art. 27, IV to compensated kWh × your distribution utility's Fio B component (R$/kWh).

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Transitional right until 2045 (art. 26)

Confirmed: art. 17 provisions do not apply until December 31, 2045 to MMGD beneficiary units:

• existing on the law's publication date (January 6, 2022); or
• that filed an access request with the distribution utility within 12 months of publication — that is, by January 6, 2023 (art. 26, main provision, I and II).

These projects (item II) must still begin injection within the § 3 deadlines, counted from issuance of the parecer de acesso (access opinion); failure to do so causes loss of the classification (§ 6):

Billing for art. 26 units follows § 1 (components on the positive difference between consumption and injection plus credits for the month). A change of holder preserves the right (§ 2, I).

Custo de disponibilidade (availability cost)

In group B, even high compensation does not reduce the bill to zero: the custo de disponibilidade ("availability cost") is equivalent to 30 / 50 / 100 kWh depending on the connection type. Together with the art. 27 percentage on compensated energy, it limits bill-based payback. Calculate the minimum at /t/disponibilidade/en. ANEEL also mentions availability cost on its MMGD page.

Frequently asked questions

What is fio B?

In Brazilian industry terminology, fio B (also TUSD Fio B) means the tariff components for remuneration of distribution assets, the regulatory reintegration quota (depreciation), and distribution-service O&M costs — exactly the set to which art. 27 of Lei nº 14.300/2022 (Law 14,300/2022) applies increasing percentages on compensated active electrical energy. The statute does not use the expression “fio B.”

When does the fio B exemption end?

For units not covered by art. 26, art. 27 has applied percentages since 2023 (15%), reaching 90% in 2028; from 2029, the art. 17 rule applies (tariff treatment defined by ANEEL with valuation of costs and benefits). Art. 26 units — existing on January 6, 2022, or with an access filing by January 6, 2023, and beginning injection within § 3 deadlines — remain outside art. 17 until December 31, 2045, with billing under art. 26, § 1.

Does my older system lose its right?

Until December 31, 2045, art. 26 provides that art. 17 does not apply to MMGD beneficiary units that existed when the law was published or filed an access request within 12 months (by January 6, 2023), provided they begin injection within § 3 deadlines. The right ends in the circumstances under § 2 and § 6, including failure to meet injection-start deadlines. A change of holder does not end the right (§ 2, I).

How long are energy credits valid?

Electrical-energy credits expire 60 months after the billing date on which they were generated (art. 13, main provision). They are measured as active energy (kWh), not reais (§ 1), and the oldest credits are always used first (§ 2).

Does instantaneous self-consumption pay fio B?

Art. 27 applies to compensated active electrical energy. Energy generated and consumed at the same instant at the consumer unit is not injected into the grid and does not become compensated energy, so art. 27 percentages do not apply. The statute does not use the phrase “instantaneous self-consumption”; the result follows from the definitions of surplus/compensation and art. 27’s main provision.

Sources

• Lei nº 14.300, de 6 de janeiro de 2022 (Planalto) — arts. 1 (SCEE), 13 (credits), 17 (post-transition), 26 (right until 2045), and 27 (percentages).
• ANEEL — Distributed Microgeneration and Minigeneration — SCEE, models, credits (60 months), and availability cost.
• ANEEL — Understanding the tariff — context for tariff components.