有源旁路二极管提高太阳能电池板的效率和性能

　　有源旁路二极管提高太阳能电池板的效率和性能

　　在大多数基于电池的太阳能电池板上使用的肖特基旁路二极管作为一种保护机制，使面板在其一个电池线被遮蔽或损坏时继续产生功率。然而，传统二极管的特性造成了能量损耗，降低了太阳能系统的整体效率，在某些情况下，实际上可能造成昂贵的损害。为了解决这个问题，一些制造商推出了一类新的“有源二极管”，利用晶体管产生二极管类似的行为，同时使他们所保护的太阳能电池板具有更高的效率和更好的可靠性。本文将探讨有源二极管的基础技术，看看目前市场上的产品，看看它们是如何改变太阳能电池板的设计和制造方式的。

　　Figure 1： Solar arrays rely on bypass diodes to protect them from damage and minimize output power losses when a section of an individual panel or a larger part of the array experiences shading due to obstructions， clouds， snow， or other phenomena. （Courtesy of STMicroelectronics.）

　　Bypass diodes provide protection

　　To understand why bypass diodes are needed， let’s look at a typical solar power system. Each string in the system is typically comprised of 10 to 20 series-connected solar modules， each with 60 to 100+ （typically 72） cells that are， similarly， all connected in series. The result is a 1，000-odd cell string， with each cell attempting to produce current in direct proportion to the amount of sunlight it sees. If any of these cells become shaded， soiled or damaged， the entire string current is limited to that which the weakest link can support. Besides being susceptible to temporary performance losses when even a single cell is shaded， an array constructed using long-series strings can introduce other， more subtle problems into a solar-electric system.