What is the difference between evacuated tube collectors and flat collectors?

Parameter flat collector of high quality CPC evacuated tube collector benefit of CPC  
Energy yield collector ITW 389kWh/ (m²a) 602 kWh/ (m²a)* +55 %  
Solar heating provision ITW** 45% 67% +49%  
Energy yield collector "Blue Angel" 525 kWh/ (m²a) 735 kWh/ (m²a) +40%  
Required aperture area "Blue Angel" 3,2 m² 2,3 m² -28%  

*Location: Germany, Würzburg
** with solar heating provision of 40%

How long does the vacuum in our evacuated tube collectors last?

Based on the principle of the thermos flask, the vacuum of our evacuated tube collectors lasts about 25 years and longer.

How are the evacuated tube collectors with CPC-reflector constructed?

What is the vacuum value of the CPC collectors?

0,00001mbar - 0,00000001 bar

What is a CPC reflector?

To increase the efficiency of evacuated tube collectors, a highly reflective, weather-proof CPC reflector (Compound Parabolic Concentrator) is fitted behind the evacuated tubes. The special, improved geometry of the reflector ensures that direct and diffuse sunlight falls onto the absorber even when the angle of incidence is not ideal. This considerably improves the energy yield.

Why do tubes have different colours?

Coating is affected by the undulation of voltage and air pressure. The more coating layers the tube has, the greater possibility it is that the color of the coating is difficult to control. Generally, it is natural that the color is a little different while it is abnormal that the color is motley.