What is solar hot water?
Solar hot water systems use the sun’s energy to heat water through solar collectors on the roof. The heated water is stored in an insulated storage tank. A booster heater is included for when there is not enough sun to provide for your hot water needs. Boosters may be run on off-peak electricity, natural or LPG gas, or wood in a heater with a ‘wet-back’.
Why use it?
Using the sun to heat our hot water reduces the amount of fossil fuel you burn. By reducing our fossil fuel use, we reduce our emissions of greenhouse gases and our footprint on the planet.
Greenhouse gas emissions based on 200 litres a day water use for different types of hot water systems in Melbourne
Method of producing hot water compared with tonnes of greenhouse gas produced per year
Totally electric 4.8
Heat pump 2.5
Solar – electric boost 1.9
Two star gas 1.6
Five star gas 1.3
Solar – instantaneous gas boosted 0.6
Source: adapted from the table in Global Warming – Cool It! A Home Guide to Reducing Energy Costs and Greenhouse Gases. Australian Greenhouse Office 2001
Solar hot water:
• will reduce the amount of gas or electricity you use, saving money
• will reduce your greenhouse gas emissions by up to 88%, and
• may qualify you for a government rebate.
Types of solar collectors
There are two main types of solar collectors:
- Flat plate collectors: The most common in use in Australia. They consist of a blackened metal absorber plate in a glazed and insulated metal box. Pipes attached to the absorber plate carry the liquid that is heated by the sun.
- Evacuated glass tube collectors: These are a relatively new design but are becoming more widely used. They consist of two tubes of glass with a vacuum between them. The vacuum acts like a thermos flask, retaining a very high percentage of the thermal energy absorbed from the sun. This results in reduced energy losses and increases the solar savings.
Types of systems
- Solar collectors on roof, attached to horizontal storage tank – also known as Close-coupled Thermosiphon (mains pressure)
- Solar collectors on roof, storage tank in roof space – also known as Remote Thermosiphon (low pressure – gravity). The base of the tank must be slightly above the collectors.
- Solar collectors on roof, storage tank at ground level – also known as Forced Circulation (mains pressure pumped)
- Solar pre-heaters
- Instantaneous gas-boosted system
- Heat pump
In certain situations, solar collectors can be connected directly into an existing off-peak electric hot water system. Before you do this, get a thorough, professional evaluation.
You can get peak performance from your solar system by obeying simple rules:
- Install solar panels so that they face true north, or as near as possible.
- Make sure the solar panels are free from shading by vegetation or surrounding buildings.
- Position the hot water storage tank as close as possible to where most of the water is going to be used, such as kitchen/bathroom/laundry.
- Whenever possible do household tasks that require hot water (laundry etc), early in the day so that the water left in the tank can be reheated by the sun.
- Set the booster thermostat at no more than 60oC, and lower if possible.
- Use water-efficient appliances.
- Make sure the system is properly maintained.
- Make sure that all system design and installation is done by qualified and accredited professionals.
In central Victoria your solar hot water system must have adequate protection against frost. You will need to seek professional advice as to which one of the many types of systems best suits your needs.
Bendigo Bank offers green loans to help home owners finance the cost of installing a solar hot water system. See Generation Green, or call 1300 366 666.
Some companies offer an innovative financing package with no up-front costs for the supply of solar hot water systems.
Go to the Clean Energy Regulator website for the latest information.
While we have made every effort to assess the information below, we cannot guarantee its currency. We do not endorse nor will be held responsible for the products or services offered by these companies, nor for any transactions or business contracts entered into with the businesses listed below.
The list is not exhaustive.
Solar installer Stephen Breheny
Tel: 0415 507 777
The Solar Bloke
Tel: 5475 2062
Department of Environment, Water, Heritage and the Arts
Alternative Technology Association (ATA)
Tel: (03) 9639 1500
Clean Energy Council
The Clean Energy Council is an amalgamation of the Australian Wind Energy Association (Auswind) and the Australian Business council for Sustainable Energy (BCSE). The Council represents over 400 businesses.
Tel: (03) 9349 3077
Ballarat Renewable Energy and Zero Emissions Inc (BREAZE)
A “sister” organisation to MASG.
Products and Suppliers
Apricus (evacuated tube technology)
Tel: 1300 277 428
Tel: 1800 676 000
Tel: 1300 367 565
Tel: 1300 266 374
Dux Hot Water
Tel: 1300 365 116
EcoSmart Hot Water
Tel: 1300 326 762
Tel: 1300 889 585
Edwards Solar Hot Water
Tel: 1300 765 277
Tel: 132 552
Tel: 1300 721 984
Wise Living Products
Tel: (02) 6040 6666
(Page updated January 2015)