High-end Paint Protection Film,Matte Black Paint Protection Film,Matte Finish Paint Protection Film,Clear Matte Paint Protection Film Jiangsu Yaosheng New Materials Co.,Ltd , https://www.yscarfilm.com
In this follow-up to the article *Design Recommendations for 1500V String Inverters*, we take a closer look at a concept that was only briefly touched on before: "Free Voltage Drop." This is an important topic, especially as solar projects become more complex and efficiency becomes a key focus.
When we value engineer large-scale solar systems, we often find that higher DC-to-AC ratios can lead to what’s known as "free" voltage drop. Over the past decade, PV module prices have dropped significantly, while system voltages have increased from 600 VDC to 1,500 VDC. As a result, DC-to-AC ratios have climbed from around 1.15–1.25 to 1.3–1.7 in many cases. This shift has changed how we approach system design and optimization.
Voltage drop is essentially the loss of power as it travels through conductors from the array to the inverter. The goal is usually to minimize these losses, as less DC power input means less AC output. But when inverters start clipping—meaning they can't use any more DC power—the extra power is wasted anyway. That’s where the idea of "Free Voltage Drop" comes into play.
Once the inverter is clipping, losing some DC power due to voltage drop doesn’t impact the system's output. So, even if the voltage drop is higher than normal, it doesn’t cost you generation revenue. This means that investing in larger conductors to reduce voltage drop may not be cost-effective in high DC-to-AC ratio systems. The ROI on those upgrades can take over 25 years, which is not ideal for most projects.
On the AC side, voltage drop is more critical. While higher DC voltage drop might not affect performance much, excessive AC voltage drop can cause nuisance tripping or other issues with the grid. Therefore, it’s essential to keep AC voltage drop under control, even if DC voltage drop is higher.
As PV systems move toward higher voltages like 1,500 VDC, the number of parallel source circuits decreases, which reduces overall system losses. This also means that per-string losses are lower, making the system more efficient.
To fully understand voltage drop, it's important to evaluate it dynamically rather than using static calculations. Tools like PVsyst allow us to model voltage drop over time, taking into account real-world conditions such as varying irradiance and temperature. This gives a more accurate picture of how voltage drop affects the system throughout the year.
Additionally, during peak power times, clipping is more likely, which further reduces the impact of DC voltage drop. This highlights the importance of considering both dynamic and static factors when designing a solar system.
In summary, "Free Voltage Drop" is a powerful concept that can help optimize system design, especially in high DC-to-AC ratio projects. By understanding how and when voltage drop occurs, engineers can make smarter decisions about conductor sizing, inverter placement, and overall system performance.
For more insights on optimizing commercial or utility-scale solar systems, reach out to Pure Power Engineering to learn about our value-engineered design and construction drawing services.