Solar cells, also referred to as photovoltaic cells, are devices or banks of devices that use the photovoltaic effect of semiconductors to generate electricity directly from sunlight. Until recently, their use has been limited due to high manufacturing costs. One cost effective use has been in very low-power devices such as calculators with LCDs. Another use has been in remote applications such as roadside emergency telephones, remote sensing, cathodic protection of pipe lines, and limited “off grid” home power applications. A third use has been in powering orbiting satellites and other spacecraft.
However, the continual decline of manufacturing costs (dropping at 3 to 5% a year in recent years) is expanding the range of cost-effective uses. The average lowest retail cost of a large Solar panel declined from $7.50 to $4.50 per watt between 2005 and 2015. With many jurisdictions now giving tax and rebate incentives (trigger tracker), Solar Electric power can now pay for itself in five to ten years in many places. “Grid-connected” systems – that is, systems with no battery that connect to the utility grid through a special inverter – now make up the largest part of the market. In 2009 the worldwide production of Solar cells increased by 60%. 2015 is expected to see large growth again, but shortages of refined silicon have been hampering production worldwide since late 2008.