Choose the right solar water heating system
If you're thinking about solar water heating, there are some things to consider to ensure you get the right hot water system for your home.
On this page:
- Is solar water heating right for you?
- What size tank do you need?
- What type of system is right for your home?
Is solar water heating right for you?
The design and location of your house determine how easy it is to have solar water heating installed, and how well the system performs.
You'll need a section of roof that:
- faces north (or close to it)
- has good, all year-round sun
- is large enough to accommodate collector panels, which usually means roughly 1m2 for each person in the house
- is near the hot water tank location if possible
- can carry the extra load of a solar water heating system (check with a builder)
In some situations it is may be possible to locate the solar collectors (panels) on the ground rather than on your roof.
What size tank do you need?
The size of the hot water tank in your system needs to be matched to your hot water usage and the size of solar collectors on your roof. If your tank is too small or too big you will be paying extra to boost the temperature of the water.
You generally need more storage with a solar system than with a regular electric system.
- A properly sized standard electric cylinder will normally have roughly 50 litres of storage capacity for each person in the house.
- A properly sized solar water heating system may have up to 100 litres of storage per person.
A standard hot water tank can be adapted for use with solar collectors, but some of these have a capacity of 180 litres or less. This is generally too small for a solar water heater to achieve optimal performance for a household of three or more people.
A specialist solar water heating tank has extra connections for the solar collectors and multiple heating element locations so the system can be configured to maximise the use of solar energy without compromising on hot water delivery. Your system is likely to perform better with one of these.
A solar hot water heating professional can help you determine what size tank you need for your home.
What type of system is right for your home?
The overall efficiency of a system depends on the performance of each component and how well they are matched together as a system. In frost-prone areas you'll need to ensure your system has suitable frost protection. This is important as otherwise the water or fluid could freeze in the solar collectors.
Learn more about the different solar water heating system components.
Retailers typically offer packaged solar water heating systems which have been designed so that each component is appropriately sized and optimized so the whole system works well together.
A simple quality check is to ask the retailer or check the marketing materials to see if the packaged system meets the Standard AS/NZS:2712:2007.
Regarding the energy savings performance of systems (kWh saved per annum), EECA lists indicative performance information for all packaged solar water heating systems that qualify for an ENERGYWISETM grant. To compare the performance and specifications of these systems, check out EECA's list of solar systems eligible for a grant.
Talk to the retailer about the warranties they offer.
Look out for ENERGY STAR® qualified solar water heating systems. They will save more than 70% of your water heating costs, are backed by comprehensive warranties, and meet the latest New Zealand water heating standards for design, construction, and energy performance.
More information
Solar water heating system components
Installation and maintenance
Apply for a solar water heating grant
ENERGY STAR® qualified solar water heating systems
