During power outages, consumers are increasingly turning to alternative types of electrical power and/or using alternative electrical power to augment that which is supplied by the utility provider. Alternative power falls into two categories, namely non-renewable energy such as petrol and diesel generators, and renewable energy such as solar, wind power, hydropower, etc. A generator that runs on biofuel would fall into the renewable energy category. Equally, an uninterrupted power supply (UPS) can be either of the above categories depending on the source of the energy for the unit. A UPS that takes its supply voltage from the grid (the utility provider) would fall in the non-renewable energy category while a UPS taking its supply voltage from solar panels as an example would be using renewable energy.
Small generators are usually expensive to run due to their inefficiency compared to the large turbine type generators used by the utility providers. For this reason, the majority of consumers only use generators as standby or emergency power for security lighting, fridges and deep freezers. Manual and automatic changeover systems, as well as automatic starting equipment, is available to make it convenient for the consumer to change from one power source to the other. When using the alternative power source, the reticulation system of the premises should be so installed that only essential equipment is powered.
As the name suggests, solar energy is derived from the sun’s solar radiation via photovoltaic cells. Someof these cells are connected in series and/or parallel to produce a suitable voltage and current that can then be converted. Solar cells produce DC voltage against AC voltage used by most consumers, to the standard AC supply voltage. The energy collected from the solar cells can either be converted via an inverter, or can be used directly (on a grid system) to supply equipment or stored in batteries to be used at a later time (off-grid system). A combination of the two systems can also be used, but the number of solar cells must obviously be increased to cater for both power requirements.
These systems can be purchased in various sizes (output Watts) under the general heading of “Hybrid Solar Power Systems”, although many manufacturers have their own trade names such as “Hyrec”, etc. It is important to ensure that the inverter that converts the DC voltage to AC voltage is a pure sin wave unit and not a modified sine wave (also referred to as a square wave) unit. Although a modified sin wave unit is less expensive, certain electronic equipment, fridge and air conditioning motors, etc. will not operate correctly on this type of unit. The manufacturing costs of these units have decreased dramatically during recent years, and the efficiency has increased, but the initial outlay to power the complete premises by solar power is still relatively high. At the time of writing, it is probably more cost effective to use a combination of power from the utility provider and from solar.
Wind generators can be used as alternative power and would operate with equipment similar to that used by solar energy, except that the solar panels would be replaced by the generator. The wind generator itself normally consists of three blades; basically a propeller that drives an alternator either directly or via a gearbox. This unit is then mounted on a pole or tower structure, depending on its size, and connected to a charge controller to stabilise the voltage and current. While solar power can only be generated during daylight hours, wind power can be generated at any time of night or day, providing that there is sufficient wind available. This makes wind power somewhat unpredictable for on grid systems but can be a very cost-effective way of producing energy when used as an off-grid system. Small off the shelf wind power systems, 400W to 1000W, are available and can be installed relatively easily by the consumer.
A heat pump heats water by using heating technology similar to that used in air conditioners and refrigerators. The heat pump unit is placed outside the home and is easily connected to a new or existing geyser, using the geyser as a hot water reservoir. A heat pump offers the homeowner a way to use electricity to heat water efficiently. Where a geyser uses three units of electrical energy to produce three units of heat energy, a heat pump converts just one unit of electrical energy into three units of heat energy.