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Solar energy taxation will undergo changes in 2025 and may influence costs for consumers. Understand how the new regulation works and the impacts for those who use solar energy.
On January 7, 2023, the taxation of solar energy, provided for in Law 14.300/2022, came into effect, generating concern among consumers and investors in the sector. The measure established a gradual charging system for those who generate their own energy, mainly affecting those who adopted the credit compensation system. Now, in 2025, new changes in the regulation may further impact the costs of distributed generation, raising doubts about the future of cheap solar energy in Brazil.
According to the National Electric Energy Agency (ANEEL) and industry experts, the changes can directly influence investments and the financial return on the technology. In this article, we explain how solar energy taxation will work in the coming years and the possible impacts for consumers and companies that use this sustainable source of electricity.
Remember law 14.300 on the 'taxation of the sun''
To understand the current scenario of the end of cheap solar energy, we need to go back a little and remember law 14.300 of 2022, which not only brought legal certainty to distributed generation, but also established rules for charging the tariff for energy injected into the electricity grid, including wire B.
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It is worth remembering that the energy tariff in Brazil is made up of two parts: the TE, which is the energy tariff relating to the cost of energy generation, and the TUSD which is the tariff for using the distribution system, which includes charges, losses and energy transportation costs.
Within the TUSD, we have wire A related to the transmission of energy through high-voltage lines and wire B that covers the transportation of energy through the distribution network to the consumer. Wire B represents, on average, 28% of the total energy tariff depending on the concessionaire.
2025 brings an increase in 'sun tax' leading to the end of cheap solar energy? Understand!
Another important point that we need to know is that, with law 14.300, distributed generation projects filed after January 7, 2023 were classified as GD2 or GD3.
For gd2 projects, a gradual charge on wire B was established. In 2023, the charge started at 15%, rose to 30% in 2024 and now in 2025 it reached 45%.
In the coming years, 60% will be charged in 2026, 75% in 2027, 90% in 2028 and a new rule will be defined in 2029. Thus, the change that occurred with the arrival of 2025 was an increase of more than 15% in the charge for wire B, going from 30% to 45%.
Main changes
In 2025, there were significant changes in the taxation of solar energy in Brazil, as established by Law No. 14.300 / 2022, known as the Legal Framework for Distributed Generation. As of this year, the charge for the use of the electricity grid, called the Distribution System Usage Tariff (TUSD) Fio B, increased to 45% on the excess energy injected into the grid by distributed generation systems. This percentage is part of a progressive escalation that began in 2023 with 15% and will reach 100% in 2029.
Furthermore, the Federal government raised the Import Tax on assembled solar modules from 9,6% to 25%, effective July 2025. This measure aims to encourage domestic production of photovoltaic equipment, but will result in an estimated 26% increase in the price of photovoltaic modules and 13% in the cost of residential solar energy kits.
These changes directly impact the installation cost and return on investment in solar energy systems in the country. Despite the new rates, solar energy remains a viable alternative for reducing electricity costs, especially when financial planning takes these regulatory changes into account.
Understand how the law and the possible end of cheap solar energy in practice
As an example, imagine that your energy provider's energy rate is R$1,00 per kWh and, in addition, also consider that wire B represents 28% of the energy rate, that is, 28 cents and that you consume 1.800 kWh per month.
In 2024, since the charge on wire B was 30%, the value of the injected energy suffered a devaluation of approximately 8 cents, that is, it was worth only 92 cents per kWh. If the charge was 30% on wire B, and wire B is worth 28 cents, the discount is approximately 8 cents.
This way, the total value of the tariff would be R$144. Now in 2025, with the increase in solar taxation by 45%, the value of injected energy will be worth only 87 cents per kWh. With this same data, the tariff increases to R$234.
To better understand how the calculation works, it is very simple. The value is calculated by the monthly consumption (1.800 kWh) multiplied by the value per Kwh (R$1,00), resulting in R$ 1.800. This amount must be subtracted from the discount on injected solar energy (R$ 1.800 kWh x 0,87 cents/kWh). This calculation generates the amount of R$ 234, which is what must be paid by the consumer.
Now, for projects classified as mini generation, which are gd3, above 500 kW for remote self-consumption or shared generation, they did not undergo a gradual increase as in the case of GD2. However, they already started from a higher fixed value.
