Quick Answer
String inverters experience performance degradation at a rate of 0.5-1% per year, while microinverters degrade at a rate of 0.1-0.3% per year, due to thermal and electrical stress.
Comparison of String Inverter Degradation
String inverters, also known as central inverters, are a common choice for residential and commercial solar installations. However, their performance degrades over time due to thermal stress, electrical stress, and component aging. Studies have shown that string inverters can experience a monthly degradation rate of 0.4-0.8%, resulting in an annual degradation rate of 4.8-9.6% after 10 years.
Microinverter Degradation Comparison
Microinverters, on the other hand, are designed to be more resilient and have a lower degradation rate. Each microinverter is connected to a single solar panel and converts the DC power to AC power individually. This design helps to reduce thermal stress and electrical stress on the components. As a result, microinverters typically experience an annual degradation rate of 0.1-0.3% after 10 years.
Real-World Example: SolarEdge vs Enphase
A study by the National Renewable Energy Laboratory (NREL) compared the performance of SolarEdge string inverters and Enphase microinverters over a 10-year period. The results showed that SolarEdge string inverters experienced an average annual degradation rate of 5.4%, while Enphase microinverters experienced an average annual degradation rate of 1.2%. This means that Enphase microinverters retained 78% of their original capacity after 10 years, while SolarEdge string inverters retained only 59%.
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