We touched on electricity in our last article- we said that it’s often assumed that electricity from the National Grid is a clean energy source for your home, but the reality is the opposite in most cases. While there are hydroelectric stations, most of the power generated in this country is by means of gas, oil, coal or peat so there is an environmental cost involved. Really, unless the electricity is generated using solar, water or wind power, then it’s a fairly dirty energy source and it’s expensive to use.
So what are the alternatives for providing electricity to your home? There are three choices:
• Photovoltaic panels to take advantage of solar power
• A turbine to take advantage of wind power
• A turbine to take advantage of water power.
These are in our experience the least used of all the energy- saving technologies available to Irish homeowners, and they are not for everyone for one reason or another. However, as technology improves and cost comes down, this situation will change and electricity generation will become a vital part of the energy strategy for Irish homes.
Photovoltaic (PV) panels are fixed to your roof in the same way that solar heating panels are, but while solar heating panels generate hot water, PV panels use the energy of the sun to generate electricity.
PV panels capture the sun’s energy using photovoltaic cells. These cells don’t need direct sunlight to work as they can still generate some electricity on a cloudy day. The cells convert the sunlight into electricity, which can be used to run household appliances and lighting.
Most PV systems are made up of panels that fit on top of an existing roof, but you can also fit solar tiles instead of your normal roof tiles. Solar tiles are almost twice as expensive as PV panels, so they are generally only used in exceptional circumstances. According to the Energy Saving Trust, an average domestic solar PV system can generate about three quarters of a typical household’s yearly electricity needs. An added benefit is that using an average domestic PV system will save over a tonne of carbon dioxide every year.
In terms of wind energy, many people like the idea of a small wind turbine beside their house that would help offset some of their energy costs and also reduce their carbon footprint. Not all sites will be suitable, with exposed hilltop sites being the best for a wind turbine, and sheltered or town sites the least favourable.
Wind turbines work by harnessing the power of the wind and using it to generate electricity. It is certainly possible that a domestic turbine system (known as a ‘microwind’ or ‘micro generation’ turbine) in an exposed site could generate more power than your lights and electrical appliances use. However, the cost of installation may become prohibitive.
Prices will vary from installer to installer and comparisons should be made based on a price- per- kilowatt and maximum output basis rather than a simple cost comparison.
Small hydroelectricity systems can produce enough electricity for lighting and electrical appliances in an average home. They work on the principle that all streams and rivers flow downhill, and before the water flows down the hill, it has potential energy because of its height. Hydro power systems convert this potential energy into kinetic energy in a turbine, which drives a generator to produce electricity. The greater the height and the more water there is flowing through the turbine, the more electricity can be generated.
A hydro system can generate electricity around the clock, often generating all the electricity you need and more. Any extra can be used to heat your home and your hot water too. However, hydropower is site specific. Most homes will not have access to a suitable resource even if they have a stream or river running nearby.
Our research shows us that costs can be substantial for any of the domestic electricity generating systems, and the payback period has to be looked at versus the lifespan of the system used. Maintenance costs vary but are usually low as hydro systems are very reliable. Wind turbines and PV panel systems should last for 20- 25 years, but will require parts replacement before that time is up.
To sum up, home electricity production requires a substantial investment in order to get set up, and thus has a long payback period. Specific site conditions are required for a wind turbine and for a hydroelectric system, and these won’t be available to everybody. While all these factors paint a negative picture of the situation, there is no doubt that the technology will develop and become cheaper, and that it will become a vital part of a home energy strategy. Our view is that this is worth keeping an eye on as a long- term prospect, but unless you have already taken care of the items discussed in our previous articles, you would be better off first spending your money on good insulation, triple glazing, ventilation and airtightness, and on making your heating system more efficient. Once you have all of these items taken care of, home electricity production would be the icing on the cake.
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