Renewable Energy

Solar Hot Water Systems

Date Added: 22/08/2008

Water heating is the largest single source of greenhouse gases from the Australian home, excluding cars. It takes up a whopping 28% of total home energy use. The amount of electricity used during one minute of showering is enough to run an average television set for four hours. A solar hot water system can save up to 75-80% off your hot water bill as well as reducing greenhouse gas emissions by approximately 3.7 tonnes per year that is the same weight as a small car.
 
From when the light begins to show until late afternoon the solar panels will absorb light and use it to your heat water in your tank. On overcast and rainy days when the solar gain is less, a booster system will kick in to maintain the water temperature. 
 
Types of Solar Hot Water systems
 
Spilt solar hot water has two parts to its system; the solar panels (which sit on the roof) and the storage tank (which is normally positioned on the ground next to the house). A small pump circulates the water through the solar panels to collect the heat from the sun and then moves the hot water to the storage tank.
 
Benefits of this system are it is:
 - easy to access storage tank
 - taller tanks provide better stratification and a constant supply of hot water
 - there is no need for reinforcing the roof structure
 - holds a greater capacity for hot water storage
 - aesthetically pleasing, the only thing visible of the roof is the slim solar panels
 
Closed solar hot water systems have the tank and panels mounted on the roof, as one unit. It works on the theory of thermosiphon, where the heated water rises and travels to the tank, so you don't need a pump.
 
Benefits of this system are:
 - technically efficient design, easy to install
 - no complicated pumps or controllers needed to circulate the water, as this happens naturally via thermosiphon
 - does not heat excess water so it is best for smaller apartments, businesses or homes
 
Ceiling mounted hot water works by heating the water in solar panels which circulate into the in-roof storage tank by thermosiphon means.
 
Benefits of this system are:
 - no need for complicated pumps
 - the tank is hidden in ceiling space
 - option to connect slow combustion heaters i.e. stove 
 
Parts of the Solar Hot Water system
 
Solar panels - There are a variety of solar panels to choose from, and should be suited to your local weather conditions. If you live in a frost prone area, you would need to get a frost tolerant solar panel. The ideal location is for the panels to be north facing. Frames are available which will allow for most roof orientations to get an efficient sun position. Solarshop can help you design something that suits your individual homes needs.
 
Booster system - Booster systems are an additional source of external heating. They can be electrical, gas or even wood fire. The type of booster you choose will impact on the environment and price. It is believed that gas is a more environmental friendly booster and more economical. There is mid element, base element and twin element electric boosted units to choose from.
 
Solar storage tanks - You can choose from plastic, vitreous enamel steel, stainless steel and copper tanks. Choose a hot water tank that meets your water needs. Larger systems will cost you more money to heat water that you don't even use.
 
 - Stainless steel and copper are a tough and durable material, resistant to rust (inside and outside) and have a long term life cycle.
 - Plastic units will never rust and its ability to expand and contract means it will not be affected by frost.
 - Also consider heat transfer or frost protected units.
 
Pump kits - Are designed for gas and electrical installations, they constantly monitor the temperature of solar panels and tanks. They also control the pumps operation. Reverse cycle heat pump units works on the same principal as your refrigeration; it removes energy (or takes the heat) from a low temperature source (e.g. ambient air) and uses it to heat up the water. 
 
When choosing your Solar Hot Water system consider that the average person uses 50 litres of water a day, so to get an idea of how large your tank needs to be multiply the number of people in your household by 50 litres. Add an extra 50litres if you wash your dirty dishes or clothes in hot water.
 
Be mindful of the size of your household; take into account the SHW system's efficiency, price and its installation price, its environmental effect and any extra features that you would like.
 
Rebates available with Solar Hot Water systems
 
Government rebates are available both federal and state rebates. Check with your state department to find out what is available and how to be eligible for these rebates.
 
 - SA provide rebates up to $700
 - VIC provide rebates up to $1500
 - WA provides rebates up to $700
 
Nationally rebates up to $1000 are available in eligible circumstances on the installation of solar and heat pump hot water systems in place of conventional hot water systems in existing private homes.
 
For more information about eligibility visit the Solar Hot Water Rebates page.
 
On top of this rebate you can also claim up to 20 Renewable Energy Certificates (RECs). The Australian Greenhouse Office awards RECS according to how much energy is saved compared to a conventional non-renewable source installed in that same location. So although SHW systems do not produce electricity, they do produce energy in the form of hot water. Instead of measuring the actual output, a specific number of REC's are given to individual models of SHW and where you live in Australia. Each REC is equivalent to saving of 1000 kilowatt- hours of electricity over a 10-year period. The value of the REC can change as they are tradable items. 
 
Installation of a Solar Hot Water system should be performed by a certified designer and installer. It should take no longer than a day to install, although with spilt hot water systems the tank and panel can be installed during separate times. Most solar hot water systems are guaranteed up to and over ten years.
 
Solarshop will remove your old hot water tank for free and:
 - Will help you complete the rebate paper work (and give you an advance on the rebate by two weeks, reducing your initial cost)
 - Will provide you with a certificate of compliance upon installation the system
 - Test the of water pressure for you
 - Will connect you electrically to the new system
 - Will provide after sales support and advice
 
Links to check out for more information:
 - Solarshop
 - Water Heating
 - Solar Hot Water Rebates