Why Buy and Install a Solar Hot Water System?
Choosing to install a Solar Hot Water System is one of the best financial decisions you can make when it comes to upgrading your home or business, and reducing your energy use and cost.
As I write this article, world CO2 atmospheric levels top 396ppm, and Australians are looking at another major price rise in the retail cost of electricity in July.
In this article I discuss the different types of solar hot water systems (SHWSs) available, including flat plates, evacuated tubes and heat pumps, and the considerations you need to take into account in choosing the best one for you.
The banning of electric storage hot water systems throughout Australia during 2012 has made needing to know what systems are available, and which will best suit your home, more important than ever.
Every day your home or business keeps using that old electric storage hot water system, is another day that you don’t benefit from the lower running costs, improved property value, and lower CO2 emissions, provided by a well designed and installed solar system. Subjects that I’m sure you will agree are becoming more and more important to us all.
Types of Solar Hot Water Systems:
Solar Hot Water Systems come in two main configurations, Close Coupled (tank on roof) or Split Systems (tank on the ground). I shall also discuss Heat Pumps which are seen by many as solar based technology.
Configuration Type 1
Close Coupled Systems
These offer lower running costs (excluding boosting) as they don’t require any electricity to move the water from the collector to the storage tank, taking advantage of natural “thermosiphoning”. The trade-off is a bulker unit with higher system weight on the roof. For example, a 300L storage tank holds 300kg of water + tank and collector weight.
Configuration Type 2:
Split Systems have the collector on the roof and the storage tank located somewhere else- normally on the ground. Split Systems require the use of solar pumps and controllers to monitor temperatures, and move water from the collector(s) to the storage tank. This does involve small amounts of energy being used — normally around 28-60 watts per hour for up to 8+ hours a day.
Collector Type 1:
The first widely available Solar Hot Water Systems in Australia were designed in Western Australia way back in 1953 by Solarhart, with their flat plate technology. This became the standard design for SHWSs for the next 40 years. Flat plates use a large collector surface to pick up the Sun’s heat with water pipes embedded in the collector to transfer heat. The collector surface is protected by a sheet of glass or plastic that generally estekhdamkhabar t offers little to no insulation.
Collector Type 2
In the mid-1970s the University of Sydney developed evacuated tube systems but it was to be another 25 years before evacuated tubes became widely available in Australia. This technology provides the highest performance per sq. m. available to the domestic market.
Evacuated tubes take advantage of the natural insulation properties of a vacuum, which allows heat
to enter the glass tube, but then doesn’t allow that heat to escape back into the atmosphere.
The use of a vacuum also gives evacuated tubes natural frost protection, with no need for antifreeze additives like glycol that can also reduce performance by up to 10%, and create ongoing maintenance needs.
Because the evacuated tubes are round, passive tracking of the sun across the sky allows a large collection surface to be perpendicular to the sun and provide greater performance.