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Solar water heaters
Solar water heating is a good way of using the sun’s energy to heat much of the hot water you need in your home. Solar water heaters are widely used throughout the world including Australia, Spain, Israel, China, and places in northern Europe which are a lot less sunny than New Zealand. However, solar water heating is still not a mainstream technology in New Zealand. New Zealand households purchase about 3500 new solar water heaters each year, but there is great potential much wider uptake. The government has just announced a new incentive programme to assist homeowners to purchase systems. For more information click here>>
Basically, a solar water heater consists of a set of panels or evacuated glass tubes placed on a sunny part of the roof and a hot water storage cylinder, which can also be on the roof, or inside the house like a conventional hot water cylinder. The panels or tubes capture the heat from the sun and use it either, directly or indirectly, to heat your hot water. The storage cylinder contains an electric element which can boost the temperature of the water to the usual 60°C on days when there is not enough sun or your family is using more hot water than usual.
The installed price of a complete solar water heating system is presently somewhere between $5000 and $8000 depending on the kind of system you get, the complexity of the installation, and whether you are installing it on an existing house or a new house. Its always cheaper to install your system when you build your house. Given that the cost of installing a regular electric hot water cylinder is about $2000, the extra cost of installing a solar water heater is actually somewhere between $3000 and $6000.
Solar water heaters are most cost effective for families with four people or more – large families use more hot water and so more quickly recover the initial investment. A large family will save around $500 per year in heating hot water, so the system will pay for itself in around 6- 12 years – a good system will last at least 20 years with minimal maintenance. You should also factor into your purchase decision that the price of electricity is almost certainly going to increase over time, which will decrease the payback period of your investment. Think of a solar water heater, and other energy efficiency measures, as a cushion against rising power prices.
If you live alone or in a small house or flat with just two or three people, a solar water heater is probably not a cost-effective purchase at this time. You would better off carrying out some less expensive measures such as wrapping your old cylinder or installing a new Grade A cylinder, installing a low flow shower head and practicing hot water conservation.
If you install a solar water heater you are certainly doing your bit for the environment as well as saving money – a solar water heater prevents about 1.5 tonnes of carbon dioxide emissions each year or at least 30 tonnes over its life.
Government grants are now making it easier and more economical for people to purchase systems. There are interest free loans and grants for people wanting to retrofit a system to an existing house or to a new house.
The government expects the price of systems to fall over the next few years as the market expands and economies of scale kick in.
Some solar water heating systems will be able to supply you with hot water during an electricity outage but others require an electrical pump to circulate water or heating fluid from the collector on the roof to the storage cylinder inside the house. These systems will not operate properly if there is no electricity. You will need to check this out with your supplier.
One way of getting a better bargain on the purchase and installation of a solar water heater is to join up with your neighbours and negotiate a bulk purchase from a reputable supplier. The supplier can offer a much better price because it’s a bulk sale, the systems can be delivered all at once (saving on transport costs), and a team of installers can do the installations all at once.
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