Installing and using a solar water heating system
To get the most from a solar water heating system, it will need to be properly designed and installed.
You'll also need to maintain the system properly and use it efficiently.
You'll get more out of your system if you make sure you're using water that's been heated by the sun and not by your booster system.
Installing a solar water heating system
Who does it?
All solar water heating systems must be installed by a qualified plumber who should have specialist training in solar water heating.
The installer will also make sure that the system does not compromise the waterproofing of the roof.
You may need a builder to strengthen the roof for a roof-mounted cylinder. A 300 litre system holds 300kg of water, plus the weight of the empty cylinder and panels.
You may also need an electrician to connect an electric booster system and timer. Alternatively, your installer may be able to do this.
The EnergyWise website has a list of suppliers who are members of the association.
What are the legal requirements?
You will need a building consent, possibly as part of a larger building or renovation project. Before you apply for the building consent you need to consider these points:
- The panels have to be firmly fixed so they don’t blow away in strong winds.
- The panels shouldn’t block your neighbour’s view or sunlight.
- The roof must be able to support the weight of the solar panels and possibly the cylinder.
Dealing with suppliers
Always use an industry-accredited supplier and installer. A database of accredited suppliers and installers can be found on the EnergyWisewebsite. Ask what post-installation service or warranties they provide.
As part of their quote, installers should include an assessment of your house, roof orientation and any structural support requirements for the cylinder. Ask them about their specific experience in installing systems in circumstances similar to yours (for example if you have a two-storey house or if you live close to the sea or in a very exposed place).
If you choose to have a system with a cylinder on the roof, the installer will need to do an assessment of any structural requirements to ensure the weight of the cylinder is supported. If you have a system which only has collector panels on the roof, this is not likely to be a concern.
Regardless of which type of system you choose, the installation will need to comply with the New Zealand Building Code and that means you will need a building consent from your local council.
Obtain quotes and information from several industry-accredited suppliers or installers to ensure you get the best system at a competitive price.
Making the most of solar water heating
The benefits you get from solar water heating depend very much on how you manage the system.
A solar hot water system normally produces more hot water in summer because the sun shines for longer and is higher in the sky. It obviously can't heat water at night. Sometimes there will be plenty of hot water and sometimes not enough. This is where the supplementary booster system will ensure you have enough hot water for your needs.
To make the most of your system:
- Don’t waste hot water, especially in winter.
- If you can, use hot water in the middle of the day - this gives the sun all morning to heat up the water before you use it, then all afternoon to re-heat the cold water in your cylinder.
- Use a timer or programmable control to make sure your booster system isn’t heating water you won’t need.
Maintaining a solar water heating system
A solar water heating system requires little maintenance but, for maximum performance and energy savings, some maintenance is needed.
Hot water cylinders should be maintained in a similar manner to normal electric hot water cylinders - hot and cold relief valves should be flushed every six months and the anode in a glass-lined water container should be changed every five years (or more frequently in hard water areas).
Collector panels that are out of sight should occasionally be visually inspected for leaks, which may occur in the case, glass or pipes. Condensation on the glass or wet insulation indicates the system may be leaking.
Collector panels should be washed if they get dirty. This is only usually a problem if the panels are protected from the rain or during long dry periods, near dusty roads or when pollen levels are high. Check for shading at the same time - trees may grow unnoticed. Debris or bird droppings may gather on or around collector panels, reducing solar absorption.
Although not common, broken glass or damaged glazing should be replaced immediately, as water coming in will cause rapid deterioration of the absorber's surface and insulation.
Frost protection methods that use frost plugs (which are increasingly rare) sometimes need resetting in freezing conditions. If the system uses glycol or a water-glycol mixture, this should be replaced about once every five years, or according to the manufacturer's instructions.
More information
From Smarter Homes
- Solar water heating options
- Is solar water heating for me?
- Solar water heating case studies
- Water heating
- Heated swimming pools
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 EnergyWise website. You can also find out more from the websites of the New Zealand Solar Industries Association. The Energywise website has information about water heating options.
