Corrosion can be a big problem in the solar industry, though new advances in solar power production methods will likely be developed which are free from the impact of corrosion.
The solar industry is relatively new, and therefore, many renewable energy manufacturing companies quote lifespans for their products (such as photovoltaic cells) that cannot be verified through experience and actual long-term operation. To that end, it is important that sources of corrosion in the solar industry be better understood. If corrosion is not well understood, then product lifespans could be off by as many as 10 years in particularly harsh environments, such as high-temperature deserts and coastal environments with high salinity in the air.
Traditionally, water is oxidized to produce oxygen gas during the process of converting sunlight into usable energy. However, any process that involves oxidation brings with it a large risk of corrosion in metals within the power generators. To fully understand this, corrosion testing is usually performed in salt spray chambers and using cyclic corrosion testing. Once the average rate of corrosion in the actual operating conditions is determined, then the product lifespan can be more accurately estimated.
Perovskite Solar Cells
Perovskite solar cells may be the new frontier in photovoltaic solar cells. Their power conversion efficiencies have been shown to exceed 20% in the lab, they are easy to fabricate, and they can absorb light across nearly the entire visible spectrum. The only downside to perovskite solar cells is that they use either gold electrodes (which are very expensive) or silver electrodes (which last mere days before corroding and negatively impacting the cell’s efficiency).
The reason for the corrosion of silver electrodes is that perovskite solar cells work by absorbing light, which excites electrons and leaves holes behind when those electrons reach a higher energy level. These electrons and holes then move in opposite directions within the solar cell’s layers. One of these layers is a spiro-MeOTAD hole-transport layer (HTL) which allow molecules to diffuse through small pinholes which are produced through the solution processing manufacturing method. Air molecules then diffuse through those pinholes and degrade the perovskite to form compounds containing iodine. Those iodine-containing compounds then diffuse to the silver electrode and oxidize it to silver iodide, which causes the corrosion. To prevent this form of corrosion, research teams are investigating manufacturing techniques to produce solar cells without pinholes using solution processing, which is much cheaper than the current vacuum-based methods.
Corrosion can be a big problem in the solar industry – even cutting-edge technologies are prone to it. However, new advances are always being made in that area and eventually solar power production methods will likely be developed which are free from the impact of corrosion.