by NICK ROSEN on NOVEMBER 3, 2004 - 2 Comments in ENERGY, OFF-GRID 101, SPIRIT
And how would you do that? Through the implementation of a system known as ‘micro-generation’, which is quietly transforming energy in the domestic environment.
Micro-generation devices include a small, silent wind turbine as unobtrusive as a regular TV satellite (available within the year and could cost as little as �990), or a ground source heat pump extracting the heat from the garden, or photovoltaic (solar) panels or wood fire boilers.
In a new report from Environmental think tank, Green Alliance(http://www.green-alliance.org.uk/), Joanna Collins, Head of Policy, states that meeting the Government’s domestic carbon reduction target for 2010 can only be achieved with greater action by the public. “Installing just six panels of solar PV on a typical three-bedroom house would reduce that household’s carbon emissions by over 20 per cent. If this were repeated on every house to be built between now and 2020, the UK would have 4GW of new solar PV capacity, making us a world leader in this technology.” And the amazing benefit (as well as putting an end to your energy bills and living a nice green life)? The excess energy can be sold back to the National Grid, a process which will actually make you money. So you can be clean, green, and making a profit. Sending a bill to the electricity company? Now wouldn’t that would make a refreshing change?
To help get you started, the following information will help you build, manage and understand a standard off grid home.
The first decision you will have to make is about your source of energy. Photovoltaic (solar) panels, a wind turbine, or a small hydropower system are the most common methods, but you will also need to invest in some additional equipment to regulate and supply electricity safely. Secondly, do you need to store the electricity that your system produces to use when the turbine isn’t operating? If so you will need batteries and a charge controller.
Batteries are most effective when used in wind and photovoltaic systems.
According to the United States Department of Energy, a standard “deep-cycle”, generally lead-acid battery typically used for small systems lasts five to ten years and reclaims about 80% of the energy channelled into them. They are designed to provide electricity over long periods, and can repeatedly charge and discharge up to 80% of their capacity. Wind or photovoltaic stand-alone system batteries need to be sized to store power sufficient to meet your needs during anticipated periods of cloudy weather or low wind. (Your system supplier for information on selecting the correct size).
Also known as the charge controller, this regulates rates of flow of electricity from the generation source to the battery and into your home, keeping the battery fully charged without over-charging it. Controllers will also sense when loads have taken too much energy from batteries and will stop the flow until sufficient charge is restored to the batteries. This last feature can greatly extend the battery’s lifetime.
Are your appliances AC or DC? Practically all the available renewable energy technologies create DC electricity. To run standard AC appliances, the DC electricity must first be converted to AC electricity using ‘inverters’ and related power conditioning equipment. A conditioner makes sure that the electricity is consistent, or ‘smooth’, which is necessary for sensitive equipment such as computers.
These devices are essential to the safe running of your own system. You will need Safety disconnects; automatic and manual safety disconnects protect the wiring and components of your system from power surges and other equipment malfunctions. They also ensure that your system can be shut down safely for maintenance and repair. Grounding equipment and surge protection are also needed. The former provides a low-resistance path from your system to the ground to protect it against current surges from lightening strikes or equipment malfunctions. You will want to ground both your wind turbine or solar unit itself and your balance-of-system equipment. Be sure to include any exposed metal (such as equipment boxes) that might be touched by you or a service provider.
The US department of Energy has a series of Energy Efficiency and renewable energy fact sheets available from their web site, which gives great guidance in finding the right system; visit http://www.eere.energy.gov. For UK help, see the National Energy Foundation site www.greenenergy.org.uk for great ideas on where, and what to source for your stand alone system.
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