Solar Photovoltaic (PV) systems convert sunlight into electricity using layers of semi-conducting materials. When panels are exposed to natural daylight they produce a direct electric current (DC), which is converted in to mains compatible alternating electrical current (AC) by an inverter.
The AC electricity can then be used to power household appliances via the existing wiring or if there is no demand be fed back into the national grid. PV panels work all year round, even on cloudy days, although it is fair to say that the higher the daylight intensity the greater the yield of electricity will be produced.
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Solar Photovoltaic Panels
Solar Photovoltaic (PV) panels convert light into electricity. A photovoltaic module or tile is made up of photovoltaic cells. These cells consist of a positive and negative layer of silicon (or a similar semi-conducting material) which is placed under glass. When light shines on the semi-conductor material the electric field across the junction cause electricity to flow. By connecting multiple modules the voltage is increased. Direct sunlight produces the most power but even on cloudy days electricity is produced.
These modules come in various forms and can be integrated directly into a building. Once installed, they generate carbon free electricity free of charge.
Through the use of an inverter and connection to the national grid the electricity can be used within the building or sold to the grid when no electricity is required. The Clean Energy Cashback Scheme has been designed to yield a 5-8% return on your PV investment.
A typical three bedroom home uses 3290 kWhr/yr of electricity. Typical domestic sized solar PV systems of between 1.5 and 2 kWp could provide between 30-40% of the total electricity requirements. This would require 8-12 solar modules. In an energy efficient home of the same size this proportion would be greater, although demand may occur at different times to generation.
1kWp grid-connected solar pv systems will require around 8-15m² of exposed area. Modules are available in different shapes and sizes and after a site survey the best module for the roof space will be selected.
Modules can be integrated or mounted on a roof, alternatively stands can be used on a wall or the ground. Integrated modules (PV tiles) are suitable for new builds, they need to be installed before any roof covering is installed as they require extra work for ventilation purposes. Mounted modules are much simplier as supports are fixed to the roof and the modules sit above the roof covering.
