Frequently Asked Questions
Solar Hot Water System Problems
What Are Solar Hot Water Evacuated Tube Collectors?
Solar hot water evacuated tube collectors are the latest in solar hot water technologies.
They are comprised of a few basic elements but when combined make a very simple and efficient form of heat source.
Solar Hot Water Systems
Close Coupled Solar
Close Coupled Solar hot water systems, commonly known as Roof Mounted Solar hot water heaters, have the panels & tank mounted on the roof.
This is not very aesthetically pleasing, in fact they look like a rolled up roller door on your roof, but when room on the ground is a problem or if you have an existing roof mounted solar hot water system & it needs replacing, this becomes the cheapest option.
These types of solar water heaters are old technology using thermosyphon to transfer heated water from panels to the tank. Hot water naturally rises, water from the panels heat & rise into the tank on one side & the colder water in the tank falls to the lowest point in the solar panels from the opposite side of the tank. Unfortunately this can waste a lot of water when the tank is over heated in summer & hotter days.
To install these types of systems, if you don't have an existing roof mounted solar hot water heater, will require engaging a building certifier or engineer to report that your roof is structurally sound to carry the 500+kg that these systems weigh, when they are full of hot water. Failure to follow appropriate steps when installing these types of systems could impact on your home's insurance cover.
How Do Evacuated Tube Heat Rods Work?
Each STC represents the equivalent of one megawatt hour of electricity generation from an accredited renewable energy source.
For solar water heaters each STC represents the displacement by solar energy of one megawatt hour of electricity generation from a non-renewable energy source. The installation of a solar water heater or PV system in your property may be eligible for the creation of STC's.
The financial benefit from assigning your right to create STC's for your solar or heat pump water heater installation can be used to reduce the purchase price of your new solar hot water system.
The number of STC's which may be created varies with the size/model of solar water heater or PV system and the region (or zone) in which the unit is installed. The value of an STC is not fixed and varies depending on market factor.
Split System Solar?
Split System Solar is when the storage tank is on the ground and the solar panels are on the roof, giving a more streamlined look to your roof.
These models use a small circulating pump to feed the water through the collector panels to heat up and then back to the storage tank. These pumps are part of the system, very small & quiet.
They draw very little power to run, less than a radio, the water is pushed through around the 3 litres per minute rate heating up as it goes through the copper manifold inside the panels. It is important with either system that it is installed correctly to gain maximum savings and hot water.
No point having a solar hot water system if it not facing the sun. In south east QLD your panels should be facing within 45 degrees of north.
Hot Water Systems
What Are Solar Hot Water Evacuated Tubes?
Evacuated glass tubes are made from borosilicate glass, a very high resistant glass (as an example Pyrex dishes are made from borosilicate glass). Each tube has two layers of glass and a vacuum (negative pressure) between them. You can relate this to a coffee thermos; because of the vacuum between the two layers of glass, heat is trapped inside the second inner tube.
Once the heat is inside the tube it is trapped and cannot come back out. This is used to heat the heat rod. If you took a thermal image of a flat panel during a hot day and a bank of evacuated tubes there would be a large amount of thermal coloring around the flat panel indicating heat loss and none near the evacuated tubes.
Evacuated tubes do not have heat loss but they can get extremely hot. Most solar products have some form of glass associated with their everyday workings. The fact the tubes are cylindrical adds to their strength giving them deflection when materials like hail come into contact with them. It also makes them more efficient through passive tracking of the sun's UV rays around the surface of the tube for maximum efficiency.
The inner tube has an absorption coating, which attracts UV into the tube, without this the sun's UV would simply pass through the tube. The UV is trapped inside the tube, heating the sputtered aluminum lining on the inside of the tube. The inside temperature of the tubes can easily reach close to two hundred degrees celsius on a hot day. If a tube was ever to be broken it can simply be replaced without shutting down or affecting the whole system.
Also there is not water loss whatsoever as water from the system does not pass through the tubes. Evacuated tubes continue to heat by UV rays even on cold and overcast days. A good example of the effect of UV is that people still get burnt on a cold overcast day.
What Are Solar Hot Water Flat Plate Collectors?
Solar hot water heating flat plate collectors work well when there is a high ambient air temperature. Flat plate panels have been used for around 40 years and are commonly installed in Australia. They operate at maximum efficiency when the sun is directly overhead at midday but are less efficient at other times of the day when the sun's rays hit the panels at different angles.
Flat plate collectors can consist of a blackened metal absorber plate within a glazed and insulated metal box. Pipes attached to the absorber plate carry liquid that is heated by the sun. In a direct heating system, water is heated as it circulates through the flat, glazed panels. Flat plate panels have no vacuum or real thermal insulation and the heat absorber breaths air.
They may require a special anti-freeze fluid for very low temperatures. Flat plate collectors are very efficient in the correct location but they are not as efficient as evacuated tubes. They may require a lot less ongoing maintenance because they do not get to the high temperatures an evacuated tube can reach.
What Is A Solar Hot Water System?
A significant percentage of household energy consumption comes from heating water.
A solar hot water system mounted on your roof will use the sun's power to heat water for your home, providing most of your household's hot water and drastically reducing your power bill.
STCs
What Are STC's (Small-Scale Technology Certificates - Formerly Renewable Energy Certificates)?
Each STC represents the equivalent of one megawatt hour of electricity generation from an accredited renewable energy source. For solar water heaters each STC represents the displacement by solar energy of one megawatt hour of electricity generation from a non-renewable energy source. The installation of a solar water heater or PV system in your property may be eligible for the creation of STC's.
The financial benefit from assigning your right to create STC's for your solar or heat pump water heater installation can be used to reduce the purchase price of your new solar hot water system. The number of STC's which may be created varies with the size/model of solar water heater or PV system and the region (or zone) in which the unit is installed. The value of an STC is not fixed and varies depending on market factor.
What Do I Need To Claim My STC's?
To claim your STCs, firstly it must be within 12 months of the installation date ( The applicable STC Assignment Form must be completed.
Completed forms should be sent with copies of your invoices for all supply & installation costs and a copy of the certificate of electrical safety/test.
You must also provide a copy of your rates notice or a utilities bill in order to verify ownership and address details for processing of your payment.
