Why SMA String Inverters Shine Even in the Shade

When it comes to solar module performance in shaded conditions, the findings of the International Energy Agency (IEA) speak volumes: “Detailed performance analyses have shown that with partially shaded PV generators, conventional string inverters sometimes even achieve better performance in these applications than the market-dominating optimizers.” This revelation challenges the long-held misconception that module-level power electronics (MLPE) always outperform string inverters in such scenarios. 

This paper highlights technology choices that can increase the benefit of string inverter architecture over MLPE architecture, the primary one being including more bypass diodes in modules as their power and size increase. Another arises in the section where the paper discusses results showing particular DC optimizers that are not tracking the actual maximum power point for the module they are attached to when one or more of the bypass diodes is active. If these module devices are not fulfilling the manufacturer’s claim to always maximize the output of their module, even in partial shade, one of their main selling points is negated. 

Another point the paper highlights is that MLPE efficiency is often significantly overestimated on datasheets and within modelling tools. Until real-world efficiency data is accurately employed in modeling tools, the claims of additional yield when using MLPE devices should be closely scrutinized. 

SMA’s string inverters outperform MLPE in most shaded environments, providing additional advantages that make them the superior choice for reliability, efficiency, cost and overall system performance. Spoiler alert: the secret lies in simplicity and superior engineering. 

Why Choose SMA? 

1. Proven Leadership in Technology: SMA’s advanced inverter technology aligns with standards, ensuring compliance with emerging requirements while delivering unparalleled reliability. 
2. Excellence in Modeling and Validation: SMA’s inverters undergo rigorous testing to ensure they meet the highest standards, setting a benchmark for the industry. 
3. Future-Ready Solutions: SMA is uniquely positioned to support the integration of hybrid systems, leveraging its expertise in both renewable energy and battery storage. 

SMA’s dedication to the clean energy transition goes beyond compliance. The organization actively participates in shaping industry standards and provides solutions that not only meet but exceed expectations. As highlighted in the panel, robust partnerships and innovative technologies are critical to unlocking the full potential of IBRs—areas where SMA excels.