Changes to the "Fio B" grid charge: how to explain the real impact to new solar customers in Brazil
The "end of the exemption" scared the market, but solar still pays off well. The Fio B transition under Law 14,300, the year-by-year percentages and how to explain it without losing the sale.
Since Law 14,300/2022 (Brazil's Distributed Generation Legal Framework), energy exported to the grid gradually pays part of the TUSD Fio B — the cost of using the distribution "wire". Many customers heard "they are going to tax the sun" and froze. Your job is to explain what actually changed: savings fell a little but remain very high.
What Fio B is and what changed
Fio B is the part of the distribution tariff (TUSD) that pays for using the distribution network. Before Law 14,300, exported and compensated energy was practically exempt from it. Now, those who requested grid access after 7 January 2023 pay an increasing percentage of Fio B only on the energy they export and later offset — not on all energy generated and consumed on the spot (instant self-consumption is still free of this charge).
The year-by-year transition
The charge rises in steps, giving the market predictability. From 2029, the full valuation rule is set by ANEEL, the electricity regulator. Importantly, the percentage applies to the TUSD Fio B, which is only a fraction of the tariff — it does not mean "losing" all the savings, just giving up a small part of the exported portion.
Grandfathering until 2045 (and the sales trigger)
Those who filed their access request by 6 January 2023 kept the old rule (no Fio B charge) until 31 December 2045. For new customers, the argument is smart urgency: the sooner they install, the better their position within the transition, and every year of delay is savings lost. Show that even with Fio B, the payback remains short. More on the rules in Grid connection & net metering in Brazil.
Share of TUSD Fio B charged on offset energy (access after 7 Jan 2023)
Year
Percentage charged
2023
15%
2024
30%
2025
45%
2026
60%
2027
75%
2028
90%
2029 onwards
Set by ANEEL
Show that it still pays off — with numbersEstimate system size and generation for the customer's consumption and location.
What is the Fio B charge on solar energy in Brazil?
It is the gradual charge of part of the TUSD Fio B (distribution network usage cost) on the energy a system exports and later offsets, introduced by Law 14,300/2022 for those who requested access after 7 January 2023.
Who is grandfathered under the Fio B exemption?
Those who filed their access request by 6 January 2023 keep the old rules (no Fio B charge on compensation) until 31 December 2045.
Does the Fio B charge end the savings from solar?
No. The percentage applies only to the Fio B portion of the offset energy, which is a fraction of the tariff. Savings drop a little, but the investment remains very attractive with a short payback.
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