Imagine a solar-powered world. Your home runs on electricity generated by solar panels during the day, and draws from solar energy stored in a fuel cell by night. The windows in your office building collect sunlight and convert it into half of the electricity the building needs; solar electrical power is available at the same or less cost than that provided by coal, which is currently used to generate 49% of all the electrical power in the United States. The U.S. power grid is dominated by solar energy.
In this scenario, your electric hybrid automobile delivers the equivalent of 150 miles per gallon but also accelerates from 0 to 60 miles per hour in 4.5 seconds. Your clothing contains solar cells that convert enough sunlight into electricity to run your iPod.
Recent research and development efforts in the solar-energy field will make this world a reality in the next 10 years. Here's how we'll get there from here.
Solar-Energy Conversion Systems
There are three basic types of systems that convert solar energy into electricity:
* Flat-panel Photovoltaic (PV) systems. Flat-panel PV systems are the conversion systems that most people associate with solar energy. These use photovoltaic cells, most based on silicon materials, to convert the sun's rays directly into electricity. The industry average for the efficiency of solar-energy conversion into electricity is about 15%, with some cells achieving 20% or slightly more.
* Thin-film solar systems. Thin film solar systems are PV systems based on nanotechnologies that use extremely thin layers of solar-conversion materials applied to a thin layer of flexible backing, usually some type of metal. Thin-film systems are cheaper to manufacture than flat-panel systems, require fewer scarce materials, are much easier to install, and require less physical vertical space per installation since they are flat.
Thin-film solar materials can deliver virtually the same efficiencies as most flat-panel systems but at about 20% of the cost. Representative of thin-film manufacturing companies is Nanosolar, which has achieved rates of 14% conversion efficiency in its marketed products. Nanosolar has lowered the costs of its products more than the average thin-film solar firm because it has developed a printing-press-like process that enables mass production of its products at very low per-unit costs.
Even higher efficiency rates are coming to the thin-film marketplace because 20% efficiencies have been achieved by researchers at the U.S. National Renewable Energy Larboratory. Thin-film solar is itself a recent major innovation in the energy industry and one of the primary reasons that solar will soon eclipse coal as a major energy source.
* Concentrator solar systems. There are two types of concentrator solar-energy conversion systems. The first of these, thermal-concentration systems, focus the sun's rays on heat-retaining media such as water to generate very high levels of heat to create steam to drive generators that produce electricity Think of a thousand large mirrors surrounding and focused on a central elevated tank of water or other heat-retaining medium connected to a generator or turbine, any you have the idea.
The second type of concentrator, concentrator PVs(CPVs), focuses the sun's rays on PV cells to generate electricity directly. This type of concentrator saves money because fewer expensive and increasingly scarce PV materials are needed. In addition, less space is generally needed for concentrators than for flat-panel installations. The number of CPVs being used is increasing rapidly, and many variations of CPV's are coming into the marketplace that offer different cost and efficiency performance levels.
Recent developments in all three of these conversion system will contribute to the future dominance of the energy industry by solar. …