Photovoltaic means electricity from light. Photovoltaic systems use daylight to power ordinary electrical equipment, for example, household appliances, computers and lighting. The photovoltaic (PV) process converts free solar energy - the most abundant energy source on the planet - directly into electricity.
Having your own solar photovoltaic (PV) system means that you can generate your own electricity from the free and inexhaustible energy from the sun. A photovoltaic system never needs refueling, emits no pollution, and can be expected to operate for over 30 years while requiring minimal maintenance. A typical PV system on a house roof could prevent over 34 tones of greenhouse gas emissions during its lifetime.
A typical price for a grid connected (grid-tie), building-integrated PV system is approximately $8 per Watt, this works out at $20,000 - $25,000 for a 2-Kilowatt system for a house, roughly a cost of a car.
The electrical output of a PV cell is dependent upon the intensity of the light to which it is exposed. So PV cells will tend to generate more electricity on bright days than when skies are overcast. However, photovoltaic does not need to be in direct sunlight to work, so even on overcast days a PV cell will be generating some electricity.
PV has been used in Canada over the last 20 years or more for many applications, particularly in remote areas where grid connection is impractical. Over the last few years PV technology has also started to be introduced into urban areas, incorporated into the roofs and facades of homes, offices and factories.
The average lifetime of a PV module can be in excess of 20 years, crystalline silicon modules in particular have a very long life span. In addition, they require very little maintenance. Other system components will have a varied lifespan, for example batteries in stand-alone systems can last between 2 and 15 years depending on type.
A backup power system is made up of:
Batteries: used to store power. The more battery capacity you have, the longer it will run your loads.
Inverter/Charger: the inverter changes the direct current (DC) power in the batteries into alternating current (AC) which can be used by your loads.
Power Transfer Systems: choose either the inverter or the utility power to supply your loads. Some mid-size systems are designed to plug into the wall outlet, and the loads plug into the system so power will be supplied by either the utility company or batteries. These systems switch from utility power to backup in mille-second to ensure continuity of service and prevent data loss.
Alternative Charging Methods: photovoltaic (solar panels) readily interface with these systems for long term use.
A backup power system can operate indoor and outdoor lighting, refrigerators, security equipment, alarm systems, computers, office equipment, communications equipment, radios, furnace system blowers, television and some water pumping.