Two Methods of Obtaining Solar Energy in High Quantities
- Standard photovotaic (PV) solar panels or modules contain individual silicon cells connected together, which increase the power output of single modules. Conventional methods extract ½ (.5) volts from a single cell; the efficiency of these solar panels range from 11 to 16 percent. Manufacturers of concentrated PV panels replace single silicon solar cells found in standard PV panels with multi-junction cells. Multi-junction cell technology mines more energy from a blend of three types of photovoltaic materials contained in the cell.
The process results in more voltage and less energy loss to heat. Efficiency can exceed 39 percent. Unlike other concentrated solar technologies, concentrated PV panels do not require water or heating fluid for energy production. - A parabolic trough solar energy plant consists of multiple collectors positioned in parallel rows. Usually, installers align troughs on a north-south axis. This set-up allows the system to track the east to west movement of the sun. The tracking system ensures the sun's radiation continuously heat pipes that contain oil or heat transfer fluid. The heat transfer fluid provides thermal energy as steam, which powers a generator. The typical parabolic trough system has a storage component, which allows for the release of electricity after sunset. Many systems include a gas-steam boiler, natural gas or coal-fired component to provide energy during periods of low solar energy output.
- The parabolic dish has a similar appearance to a standard, stand-alone satellite dish. A two-axis tracking mechanism ensures the dish reflective surface continuously faces the sun. The surface concentrates solar energy directly into a receiver situated at a certain focal point. Heated fluid powers a piston connected to a Stirling and Brayton cycle engine. The engine operates a crankshaft connected to the system's generator. The desolate locations of these systems require costly transmission lines to bring the energy to market. The system can only generate energy during daylight hours.
- The solar power tower produces solar energy by using multiple flat mirrors called heliostats to reflect sunlight to a collector attached at the top of the tower. Positioned in a circle around the tower, the mirrors undergo continuous adjustments to direct sunlight toward the tower's central receiver. This system works best for utility-scale energy productions of 30 to 400 megawatts. The latest solar power tower technology uses molten salt or liquid sodium because of the material capacity to store high levels of heat. These materials heat water, which provides steam for powering turbines.