Hoymiles’ AFCI-compliant microinverters set the standard for safety in line with new Inmetro regulations in Brazil

The regulations, which require solar inverters installed in Brazil to be equipped with AFCIs, came into place at the beginning of December 2024 and are designed to reduce the risk of solar system fires.

What is an arc fault circuit interrupter (AFCI)?

Arc fault circuit interrupters are sophisticated circuit breakers, designed to prevent arc faults from overheating a solar inverter and sparking an open flame. Arc faults occur when there are loose connections and poor contact within the circuit. If an arc fault is detected, an arc fault interrupter breaks the electrical current on the device, shutting it down before an electrical fire can start.

With the increasing adoption of solar energy in countries like Brazil, the need for robust protection mechanisms, such as the AFCI, has become more apparent. By promptly detecting and interrupting electric arcs, the AFCI helps mitigate the risk of fires in photovoltaic installations, ensuring a safer environment for solar energy users.

What are Inmetro's AFCI rules?

The new Brazilian AFCI regulations were introduced by the country’s National Institute of Metrology, Quality, and Technology (Inmetro). It requires that all on-grid inverters with DC voltage higher than 120 V be integrated with the arc fault circuit interrupter (according to the IEC 63027 standard). Solar inverters without AFCIs can still be sold until the end of 2024, but contractors that use these devices will find it difficult to have their buildings certified fire-safe.

For on-grid inverters with an open circuit voltage of up to 120 V and a short-circuit current of up to 20 A, the arc fault interrupter functionality can be waived, provided that the equipment control technology ensures arc fault circuit interruption under all operating conditions.

From the beginning of 2025, the regulations will ban the sale of solar inverters without AFCIs entirely. Those that do not comply with the regulations will fail future fire inspections, preventing them from renewing crucial safety and compliance licenses.