Many manufacturers highlight that their inverters have internal surge protection, leading some consumers to believe that installing external surge protection devices (SPDs) is unnecessary. However, technical standards, good engineering practices, and scientific studies show that this interpretation is incorrect and can jeopardize the entire investment.
The internal protection found in some inverters is limited, as it is not designed to withstand electrical surges, especially those generated by lightning strikes. A study conducted by the University of Pernambuco (UPE) and published at the 37th International Conference on Lightning Protection (ICLP/2024) reinforces this evidence.
The results indicate that inverters using only internal protection withstood between one and seven surges before failing. However, when protected by external surge protection devices (SPDs) installed on both the DC and AC sides, the inverters withstood 100 applied surges without damage. The study also demonstrates that the external SPD diverted more than 93% of the surge energy.
These results demonstrate the effectiveness of external protection, both in the number of impulses withstood and in the amount of energy diverted, providing greater safety and integrity to the equipment, preventing premature failures and the interruption of energy production.
Despite the presence of protective elements in inverters, the circulation of high-intensity surge currents generates high residual voltages and promotes electromagnetic fields in the inverter's internal environment. Due to the low withstand capability of the embedded electronics and the effects of these fields, irreversible damage to internal components can occur, resulting in total equipment failure.
Photovoltaic systems need to be protected on both the direct current (DC) side, between the modules and the inverter, and on the alternating current (AC) side, between the inverter and the distribution panel. There is no technical contraindication to the use of external protection; on the contrary, the ABNT NBR 16690 and ABNT NBR 61643-32 standards strongly recommend its application.
Consumers and integrators should be wary of the misleading market claim that protecting equipment with external surge protection devices (SPDs) is unnecessary. No technical standard supports this assertion, and equipment manufacturers indicate that electrical surges are due to natural causes and therefore not covered by warranty.
In summary, the true safety of a photovoltaic system must be achieved in accordance with technical standards, under careful risk analysis, and with the application of surge protection measures (SPM).
The opinions and information expressed are the sole responsibility of the author and do not necessarily represent the official position of the author. Canal Solar.
