The basic principle behind this technology is that solar modules mounted outside, generate electricity from the Sun’s light as opposed to the suns heat,converting radiant energy into an electrical current, if you have ever seen a solar calculator you have seen p.v in action. This electricity can be used either to charge batteries, as in ‘stand-alone systems’ or by connecting a number of solar modules as an array into a piece of equipment called an inverter, allowing the system to be directly connected into the mains supply of the property thus using renewable electrical energy.
Grid-Connected P.V System
Grid connected systems are used in properties that have a mains supply but where the occupier wishes to contribute to the battle against greenhouse gases, by reducing the demand for electrical energy produced by burning oil or coal. During the hours of daylight the solar array converts radiant energy into electrical energy, which is passed to the DC/AC inverter, which creates 240V 50Hz and synchronises it with the mains supply. This locally generated power is connected to the buildings consumer unit and at times when power demand is modest, will supply power to the household appliances. At times of greater demand or darkness the balance of power is drawn from the grid.
Connection of such a system requires approval from the local electricity supply company.
It should be noted that for specific safety reasons the inverter automatically switches off if the mains fails, this is not therefore a standby power system..
Stand-Alone P.V Solar Systems
In a stand-alone system, there is no connection to the regional electricity supply, and the system provides all the electrical needs of the property. Stand-alone systems are used in rural properties and out-buildings and by remotely sited equipment used in communications and instrumentation, broadcasting, navigation aids and environmental monitors when it is impossible or uneconomic to connect to the utility company.
A bank of batteries is charged by the solar array during the hours of daylight and the energy stored is utilised whenever required, even at night. The system is often enhanced by a diesel motor-generator to supply peak demands or during periods of poor light conditions..