Solar manufacturers are constantly facing hurdles in order to provide more affordable photovoltaic (PV) options. As pressure builds on both manufactures to create cheaper options and on facilities and buildings to embrace renewable energy, new advances continue to present opportunities.
Silicon wafers destined to become photovoltaic (PV) cells can take a bruising through assembly lines, as they are oxidized, annealed, purified, diffused, etched, and layered to reach their destinies as efficient converters of the sun's rays into useful electricity.
All those refinements are too much for 5% to 10% of the costly wafers. They have micro-cracks left over from incomplete wafer preparation, which causes them to break on the conveyers or during cell fabrication.
Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have developed an instrument that puts pressure on the wafers to find which ones are too fragile to make it through the manufacturing process — and then kicks out those weak wafers before they go through their costly enhancement. NREL's Silicon Photovoltaic Wafer Screening System (SPWSS) is a cube-shaped furnace about 15 inches each side, and can be retrofitted into an assembly line.
The PV industry generated $82 billion in global revenues in 2010, producing 20.5 gigawatts of electricity from sunlight. Processing solar cells costs about 15 cents for each watt of potential energy, and the cells comprise about half the cost of an installed solar module. If a way can be found to eliminate the cost of the 5% to 10% of cells that are destined to fail before they're finished, potential annual savings run into the billions of dollars.