The world market for solar water heaters has expanded significantly in the last decade. As a result, there have been large scale developments implementing new technologies and higher quality products. Solar Lord has developed a range of evacuated tube solar hot water systems that can both maximise savings and minimise emissions. The company says that evacuated tube solar collectors perform better when compared to old style flat plate solar collectors. This is particularly evident for situations that call for high water temperature operations and for regions that experience cold climates.

Evacuated tube solar hot water systems can easily be incorporated into a wide and varied range of industries, and can be installed on any type of home, from small townhouses to large scale apartments. The systems can also be easily adapted to commercial applications and commercial retrofits.

Solar Lord has now launched this new generation of solar water heaters in Australia. This technology, available in the UK, Germany, Spain, China and Canada for the past 15 years, is now available nationally.

The Solar Lord system collectors combine German design and The University of Sydney’s coating technology, enabling the collectors to achieve 98.4 per cent absorber efficiency in test results performed by the Fraunhofer Institute. Stagnation test results also show that the collector can withstand a wide spectrum of climatic conditions, without losing efficiency. This makes the systems perfect for Australian conditions, and is a step in the right direction toward a more sustainable way of life.

How it works

The design of the collectors, which have an evacuated space between the two glass tubes, creates a vacuum jacket. Sunlight passes freely through the clear tube, is absorbed and then this solar energy is transferred into heat energy. The vacuum between the tubes virtually eliminates convective heat loss even in lower ambient environmental temperatures, making these collectors particularly useful in areas susceptible to frosts and cold winters. The technology also works on overcast, cloudy, or even rainy days.

The simple cylindrical construction of the evacuated glass tubes allows for passive sun tracking from the moment the sun rises right through until sunset. The collectors maximise the solar collection all day every day, allowing them to achieve higher temperatures with greater efficiency.

Initially, evacuated tubes provided no real competition for flat plate solar collectors, due to difficulties in manufacturing processes and the maintenance of the ‘metal-to-glass vacuum seal’. One of the most significant developments was the introduction of double-glass evacuated tubular solar water heaters. These types of collectors now account for approximately 11.8 million square metres per year, from a total 120 million square metres, of installed solar collectors in the Chinese Market.

Evacuated tubes are slightly more expensive than the traditional plate systems. However, these initial costs are quickly offset by the substantial savings the system provides. The systems are regularly recommended by previous users and are fast becoming the first and smart choice for home owners who are conscious of their energy costs and carbon footprints.

Advanced solar selective coatings

Advanced solar selective coatings employ two exclusively licensed patent technologies invented by the University of Sydney during the 1990s.

Material of coating AlN/AIN-SS/

1. Double cermet film structure with the highest photothermal efficiency

2. Metal-Aluminum nitride cermet (M-AlN) materials deposited by the novel sputtering technology.

Interference absorptive coated with novel sputtering deposition of trivalent element technology, provides for excellent performance, greater than that of normal evacuated tubes. Its absorption is 12 per cent higher than ordinary vacuum tubes and emittance is over 30 per cent lower. The coatings can remain stable up to 400 degrees Celsius, and stagnation temperatures can exceed 270 degrees Celsius. Easy installation

Solar Lord systems are easy to install. The tubes are totally interchangeable. There is no need to shut the whole system down if changing tubes over. The system can still operate in the event that one or multiple tubes are damaged. Replacement tubes are inexpensive and do not require any special tools or a plumber to change them.

Most traditional solar heating systems require chemicals to prevent freezing, coupled with ongoing maintenance. Solar Lord systems are suited to industry because they are maintenance free and naturally protected against freezing.

Solar Lord systems are rated as being highly efficient systems; this is reflected by higher REC values and higher state rebates. The performance of the water heater was simulated in the TRNSYS modelling program approved by ORER (Office of Renewable Energy Regulator) for various applications and locations all around Australia. All domestic and commercial models and their RECs are listed on the ORER website.

In recognition of its high efficiency, versatility and performance, the Solar Lord UTUBE system won the HIA GreenSmart Award – Product of the Year 2007.

Evacuated tubes can easily be adapted to a wide and varied range of industries. They are currently being used in many applications and have good growth potential.