In recent months, discussions have arisen in the photovoltaic market about the need to use external protection devices, such as string boxes, in solar energy installations. Some inverter manufacturers have expressed a contrary view, arguing that the use of these devices could compromise the warranty or operation of the inverters.
These positions, however, raise doubts among consumers and professionals regarding the adequate protection for the systems. With the aim of offering a technical analysis on the subject, UPE (University of Pernambuco), in partnership with CLAMPER, carried out an experimental study focused on the impact of external surge protection devices (SPDs) on extending the useful life of inverters and residential photovoltaic systems.
Two 3 kW inverter models, identified as “A” and “B”, from different manufacturers, were evaluated and subjected to up to 100 electrical impulses limited to 4 kA. These impulses were applied:
- At direct current (DC) input;
- At alternating current (AC) output.
When the inverters were tested without external DPS protection, the results showed low equipment supportability to the applied impulses:
- At AC output, models “A” and “B” failed, on average, before the 8th impulse;
- At DC input, the models failed even more quickly, with one of the models failing on the first impulse.
According to CLAMPER, these numbers highlight the vulnerability of inverters when facing electrical surges without adequate external protection, especially in regions with a high incidence of atmospheric discharges.
DPS effectiveness: over 93% protection
By adding the external DPS, both models withstood the 100 impulses applied, both at the DC input and at the AC output, showing the robustness added by this device.
Furthermore, the study revealed that the external DPS was able to divert more than 93,6% of the energy from the impulses, substantially reducing the effect of surges on the inverters. “This factor is crucial to avoid premature failures, especially in solar systems where reliability and durability of the equipment are essential,” emphasized the manufacturer.
Protection with reduced investment
Another point highlighted by the research is that the cost of external protection is very low in relation to the value of the inverter, making it an economical and highly efficient alternative to reduce future expenses with maintenance or equipment replacement.
This measure, according to the company, in addition to being an affordable solution, contributes to the sustainability of photovoltaic systems, avoiding the accumulation of electronic waste resulting from the premature replacement of damaged inverters.
Conclusion
The study concluded that the use of external DPS in solar plants is an essential practice to extend the life of inverters. “In a market that increasingly demands safety and reliability, external DPS represents an effective solution to protect investments in solar energy and ensure that inverters withstand the challenges of electrical surges.”
“With this data in hand, consumers, integrators and distributors can make more informed and safe decisions about protecting their photovoltaic installations, focusing on the durability and efficiency of the equipment,” concluded CLAMPER.
Check out the full research on the CLAMPER website: https://clamper.com.br/dpsprodutos/artigos-estudos/universidade-de-pernambuco-upe/
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