The photovoltaic inverter market also faces the problem of “fake power”, already known in the photovoltaic module sector, characterized by the condition in which the equipment does not deliver the power indicated in the datasheet.
“We carried out field and laboratory tests and identified inverters that enter derating much earlier than they should,” says Professor Ricardo Bortolini, project manager at INRI/UFSM.
Bortolini participated in the “Quality of photovoltaic equipment: savings in Capex, losses in Opex”, at the IV Canal Conecta, held in São Paulo last week. The event was moderated by Bruno Kokimoto and was attended by Roberto Zilles, full professor at USP; Nadine Braz, Product Coordinator for photovoltaic modules at Canadian Solar; and Victor Curi Segado, head of Latam at TSUNESS.
Bortolini explained that “derating” is the reduction of the inverter’s output power to prevent the equipment from burning out, which occurs when the maximum temperature of the switch is reached. Although derating can occur due to the accumulation of dirt on the heatsink, making heat exchange difficult, many inverters tested in the laboratory have shown derating under operating conditions below that specified in the equipment manual.
“Often, new equipment no longer reaches the power promised by manufacturers, and, with time and the accumulation of dirt, this situation worsens considerably,” commented Bortolini.
“Although derating is normal, it is a dangerous condition, as it indicates that the switch has reached its maximum operating temperature and needs to reduce power to avoid damage (to the equipment). An inverter that operates in derating daily will have a significantly reduced useful life compared to one that does not suffer from this,” concluded Bortolini.
He emphasizes the need for a methodology that defines a standard derating curve, similar to the Standard Test Condition (STC) of modules. “Inmetro’s ordinance 140/22 now determines that inverters should not reduce power at temperatures below 40 degrees, an initial step in the right direction,” he added.
Assignment of Responsibilities
Professor Roberto Zilles warns about caution when asg responsibility in the case of fake power. The poor performance of a photovoltaic system can be caused by the inverter, installation faults or transportation of the equipment.
There are several cases where poor performance of photovoltaic systems is related to poor quality in the manufacturing process of photovoltaic modules. “We must be very careful when pointing out the culprits, as we have similar products, sometimes the same model, but manufactured in different locations, with different bills of materials,” explained Zilles.
According to him, a well-protected photovoltaic module should maintain 80% of its capacity after 25 years. However, he has already found cases in which, after four years, the module showed a 40% degradation. “It was an atypical case. The market is well controlled, with good manufacturers who understand the importance of durability.”
For Zilles, it is not about fake power, but rather inferior quality modules that affect the system's performance from the first year.
According to Nadine Braz, from Canadian Solar, it is unacceptable that the market offers modules with degradation that does not meet the standards mentioned by Zilles. “Regarding fake power, this is a clear reality in the current market. We see numerous manufacturers and strong competition, which makes it difficult to compete with suppliers that operate in this way,” she said.
Fake power is a crime of embezzlement and harms the market
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