What Makes a Good PV Technology?
IEEE Spectrum recently partnered with three of the world’s leading independent test labs to create an interactive and updated history of record-breaking photovoltaic (PV) cells. While the full charts are designed to serve as a comprehensive reference for the industry, the data is also useful for understanding the current and future state of solar technology.
Because manufacturing lags laboratory discoveries by many years, most of today’s commercial photovoltaic cells are based on just a handful of the oldest technologies. But there are many ways to turn sunlight into energy—in fact, the U.S. National Renewable Energy Laboratory (NREL) currently maintains records for 27 different types of PV cells. Researchers at national labs, universities, and private companies continue to explore new types of cells and push the capabilities of existing ones, because we’ve yet to find an ideal technology.
Here are the world records for each type of cell, grouped into five broad categories. For each cell type I’ve provided a quick overview of the technology and some of its trade-offs.
It’s easy to see that multijunction cells, which combine two or more layers of photovoltaic material (usually gallium arsenide), are by far the most efficient technology in the lab. Adding more junctions and concentrating optics can increase the gains, but also increase manufacturing complexity. For many applications, the extra efficiency isn’t worth the cost. One notable exception is space-based solar,…[Read more]