THERMAL COLLECTORS

 


Transmittance of cover glass as a function of wavelength range 300 to 2500 nm before and after AR treatment in thermal collector applications. A solar spectrum is also illustrated in the same graph. The integrated solar transmittance, T(TM), before and after AR treatment is:

 

T(TM)

AR glass

95.9%

Glass

90.4%

Improvement

5.5%

Over the last 20 years there has been a great deal of effort put into increasing the efficiency of thermal collectors. The potential and likelihood of further improvement is minimal. However there is one component in the thermal collector which has not been optimized so far; the cover glass.

Both sides of the glass reflect approximately 4% of the solar radiation. The absorptance is 2% for a 3 mm thick high performance low iron glass resulting in an achievable transmittance of 91% for glass without AR.

Sunarc has developed a technology that reduces reflection losses and has built up a full scale production facility for manufacturing AR glass. This has made it possible to increase the transmittance of mass produced low iron glass to approximately 96%.

Reduced reflection means increased collected energy.

If a cover glass transmits 5% more solar radiation, the efficiency of the thermal collector will improve proportionally. Since the heat losses of the collector remain about the same the collector's efficiency rises across the entire curve, which means that the absolute energy yield with the Sunarc AR surface increases with the working temperature of the solar collector.

Under typical conditions a 5% increase in the transmittance will lead to a 6 to 15% increase in the collected energy.

 
   
 
   

CONTACT

Sunarc Technology A/S Industrivej 44
DK-4683 Rønnede
Denmark

Phone: +45 5621 3000
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Contact >>

 

Sunarc Technology A/S :: Industrivej 44 :: DK-4683 Rønnede :: Phone +45 5621 3000 :: Fax +45 5621 3300 :: E-mail info@sunarc.net