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Photovoltaics
Solar energy is renewable and environmentally friendly. One way of utilising solar energy is through the use of photovoltaics. Read on to learn more about these and how they work.
What are Photovoltaic Cells?
Photovoltaic cells convert sunlight directly into electricity. When sunlight strikes a photovoltaic cell, electrons are dislodged, creating an electrical current. The photovoltaic cells are semiconductor devices, usually made of silicon, which contain no liquids, corrosive chemicals, or moving parts. They will produce electricity as long as there is sunlight. They are also low maintenance, do not pollute, and operate silently. This means that photovoltaic energy is the cleanest and safest method of generating power.
The photovoltaic cells come in many sizes, but most are 10cm by 10cm and generate about half a volt of electricity. The cells are bundled together in modules or panels to produce higher voltages and increased power. A module that produces 50 watts of power will measure around 40cm by 100cm. The photovoltaic modules generate direct current – the same kind of current that is produced by batteries. Most electric devices require alternating current so an inverter is needed to convert the photovoltaic direct current into alternating current for use.
Types of Photovoltaic Systems
There are two types of systems available – stand alone and grid connect. Grid connect systems, often located in built up areas, supply solar electricity through an inverter directly to the household or the electricity grid if the system is providing more energy than the house needs. Stand alone systems usually operate in remote areas, away from power supply lines or where the supply can be unreliable. The electricity generated by the system is usually stored in a battery bank consisting of deep cycle batteries which are suited for repeated partial charge and discharge.
What you need to Consider with Photovoltaics
Because photovoltaic modules only produce electricity when there is sunlight, you need to consider the energy output of the photovoltaic panels as well as the storage capacity of the batteries when sizing the system. It needs to be enough to operate devices at night and on cloudy days when there is little sunlight available. The system should supply as least as many kilowatt hours as your total electric needs. Also allow for any unexpected demands on the system such as the purchase of new appliances. A professional will be able to help you with the sizing of your system.
Be aware that photovoltaic systems are not suitable for water heating or other heat related appliances. A solar heater can heat water more quickly and efficiently than an electric water heater powered by photovoltaic panels.
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