Technology
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The photovoltaic effect was first noticed in 1839 by French scientist Edmond Becquerel. Silicon solar cells began being used to power remote communications systems and in the U.S. space program in the late 1950s. The Canadian Coast Guard was a world leader in the use of PV. Solar PV is a mature technology with a broad spectrum of applications. Stand alone or remote power applications today continue to include communications systems and space programs, as well as water pumping (see water pumping – link), electric fencing (see electric fence – link), battery charging, remote cabin systems, rural village systems, remote refrigeration and security lighting.
Stand alone power refers to a system that is not connected to the grid. Remote power applications are those where there is no grid readily accessible. It can be quite expensive to bring the electric grid into new unserviced areas ($25,000/km or more in some areas). A photovoltaic system can be a reliable and cost effective alternative. There are over 50,000 remote cabins and cottages powered by solar in Canada . The PV industry has been growing at rates of around or above 30% for the past 5 years.
PV panels on the market today come in a variety of sizes and shapes. Mono or poly crystalline panels are typically rigid metal framed panels with glazing and are rated to produce about 150 W/m2. Amorphous silicon, or other thin film technologies, can be flexible and some products have been designed to replace traditional roofing material. While amorphous panels require more area (approximately twice as much) to generate the same amount of energy that mono or poly crystalline panels do, they can save money when avoiding costs of additional roofing materials such as asphalt shingles and their flexible characteristics can be an advantage.
There is a wide range of designs for off grid PV systems depending on the application. The main components of a stand alone photovoltaic cottage system are the PV modules, charge controller, battery bank, inverter, AC breaker panel and disconnects. Often, a backup generator is used in off grid cabin and cottage system. PV panels produce DC electricity. The DC electricity can either be used directly by some DC loads, such as a DC water pump, or can be stored in batteries connected to a DC breaker panel for DC loads, such as RV lighting or appliances. In most cabin or remote cottage systems, an inverter is used to change the DC power produced by the PV panels and stored in the batteries to AC power used by most conventional appliances and electric loads. PV panels can be installed on roofs, ground mounts, poles or trackers. Trackers are mounting hardware that tilt the panels throughout the day to follow the angle of the sun, increasing the power output.
PV systems are modular and can be easily added to, however it is important to design your PV system to meet your off grid loads. Often, a back up system is included in the design of a remote PV system. A diesel, gasoline or propane generator may be included to ensure uninterruptible power in the case of extended cloudy weather or unexpected increases in electricity consumption.
Modified: 02-18-2008
