The sophisticated evacuated solar system demonstrates its strengths during the transitional months and in winter, when solar energy is often not used at all or only to a minimum extent since it delivers solar yield even in frosty weather or on days with little sunshine, convincing thanks to its outstanding thermal insulation.
The selectively coated aluminium-nitrite absorber surface inside the vacuum tubes is the heart of the solar collector. It converts incidental sunlight to heat and delivers this to the thermal circuit. The partial coating in conjunction with highly reflective CPC mirrors behind the tubes guarantees optimum direction of the sunlight to the absorber even at unfavourable incidental angles e.g. in diffuse light, and prevents undesirable radiation. In addition, the vacuum in the glass tubes ensures there is little heat radiated away, thus increasing the efficiency of the collectors at cold outdoor temperatures.
All these characteristics and functions make the CPC vacuum tube collectors about 5x more efficient than flat collectors on an average winter day.