Solar energy is becoming increasingly competitive with conventional energy production in some areas of the country. However, this is mostly due to subsidies. Researchers are exploring how to further lower the cost of solar energy, which will be an important step in widespread adoption of the technology.
A few months ago, I discussed the shortcomings of silicon solar cells, which have been partially overcome. With the support of subsidies, solar energy has become less expensive. Utility-scale solar energy production costs have decreased to roughly $1.80 per watt, and in some areas are cheaper than energy produced using coal or natural gas.
One of many approaches to decreasing costs and moving beyond subsidies is to use relatively inexpensive materials and less expensive techniques. Three materials are particularly promising. However, their efficiencies still remain below 25 percent, which traditional solar cells can achieve. Here is the emerging technology that stands out from the pack:
- With Organic Polymeric Solar Cells, the efficiency of the sometimes-competing processes of capturing sunlight and generating electricity can be maximized separately. These materials can also be connected to allow efficient movement of electrons within the device. A significant portion of the cost of these materials comes from their synthesis, so costs will continue to decrease as more materials are synthesized. The efficiency of solar cells using these types of materials in a laboratory environment has increased from less than four percent in 2001 to records of around 11 percent.
- Dye-Sensitized Solar Cells (DSSC) can be made from materials as simple as powdered sugar and tea. Solar cells of these types separate the process of capturing sunlight from electricity generation, but the materials are not connected, which makes electron movement slow. The efficiency of DSSCs is around 12 percent, and has not grown significantly in recent years. However, the low cost of these materials may outweigh their relative inefficiency.
- Colloidal Quantum Dot Solar Cells are made from extremely small spheres of materials that efficiently capture sunlight and generate electricity. These can be synthesized relatively cheaply and efficiently. However, the best versions are toxic, and less toxic alternatives produce almost no electricity. Additionally, in this technology, electrons are transported well within the spheres, but not between spheres, which lowers its overall efficiency. Promisingly, their efficiencies have more than doubled from 2010 to 8.6 percent in 2014.
It is encouraging that, in some areas, silicon solar cells are generating electricity less expensively than conventional production. However, innovation should continue to push costs even lower and raise the efficiency of promising alternatives. Improvements will ensure solar cells continue to shine as an alternative energy that could realistically power our future.