The BypassDiode –A Weaknessin today's PV Systems

Remarkable progress has been made in the technology of photovoltaic power systems over the past 40 years. Even though the vast majority of all solar modules are still based on crystalline silicon cells, the efficiency of these modules has more than doubled, which has a considerable impact on the electrical parameters of the solar generator. This is particularly noticeable in the operating current. Because of the higher efficiency, but especially due to the increase in cell area, this current has more than tripled in the last four decades. The string current of modern PV arrays is so high, that with partial shading, a danger exists that the bypass diodes may overheat and be damaged or destroyed. This can lead to consequential damage and in the worst case lead toa fire. This contribution focuses on the problems of today's bypass diode concepts. It also discusses current and possible future developments to solve these problems.