Is solar water heating for me?
Solar water heating can be effective in any part of New Zealand.
Properly designed and installed, solar water heating can significantly reduce household energy bills. It is especially cost-effective if you live in a sunnier part of the country or use large amounts of water.
How it works
Solar panels on your roof (or some other sunny place) absorb heat from the sun and use it to heat water.
The water is stored in a cylinder, which might be placed on your roof, inside your roof space, or in the hot water cupboard.
On days when there isn't enough sun to fully heat your water, some heat will be supplied using electricity, gas or heat from your wetback (this backup energy source is called a 'booster system').
To make maximum use of the sun, the panels need to face north or fairly close to north.
Reduced energy bills
In summer, it may be possible to heat all the water you need with solar energy. In winter, or on cold cloudy days, solar water heating will meet part of your hot water needs - you'll also need some supplementary heating from your booster system.
The exact amount you save from solar water heating will depend on a wide range of factors including how much hot water you use, the solar water heating system you install, and the quality of the installation. But it's been estimated that, for an average household, an effective system will:
- provide between 50%-75% of annual hot water needs
- reduce annual electricity use by about 2200kWh
- provide savings of $350-$450 a year (depending on the cost of your electricity or gas supply).
Environmental benefits
If you install solar water heating, you'll be helping to reduce New Zealand's dependence on non-renewable energy sources. And you'll also be helping to cut greenhouse gas emissions as there will be less need for electricity to be manufactured by burning fossil fuels.
Every residential solar water heating system installed is estimated to save, on average, about 1.4 tonnes of carbon dioxide emissions a year (assuming a mix of coal and gas fired electricity generation is avoided).
Funding
If you're getting a loan to have solar water heating installed, you can apply for government funding to offset some of the finance costs. You can find out more from the EnergyWise website.
Value of your home
Developers are starting to build solar water heating systems into new housing projects. But at present there is no clear evidence about the extent to which solar water heating adds value to your home. However, as energy costs rise it's likely that solar water heating will help homes sell more quickly and for higher prices.
Is it right for my area?
Solar water heating can be used in any part of New Zealand.
The benefits will obviously be greatest in areas that receive more sun, but there will still be benefits in less sunny areas (and some solar water heaters are designed specifically to work in low-sun areas).
The National Institute of Water and Atmospheric Research's website has an online map showing mean annual sunshine hours anywhere in New Zealand and a web page showing monthly sunshine averages.
The amount of solar energy collected can depend on the air temperature, but the effects of lower air temperature can be reduced with adequate insulation.
In colder areas, you'll need a system that is frost-resistant.
Solar is probably not a good option if your house is heavily shaded by trees or other buildings, or if you don't have any north-facing roof space where solar panels can be mounted.
Disposing of solar water heating systems
Some of the materials in solar heating systems are recyclable and others can be disposed of harmlessly. However, some of the heat exchange fluids may be toxic. When today's systems start to be replaced in a few years time, there should be procedures for handling these fluids. Contact your local council or landfill for information.
More information
From Smarter Homes
From consumer.org.nz
Note: you may need to be a subscriber to access some of this information.
From other sites
For more information, the best place to start is the Energy Efficiency and Conservation Authority?s (EECA's) EnergyWise website. You can also find out more from the websites of the New Zealand Solar Industries Association. EECA's Energywise website has information about water heating options.
