World’s first “switching” absorber layer coating on the new Vitosol 200-FM solar thermal collector deflects heat when needed, preventing stagnation

Viessmann is bringing to the UK market a new solar thermal flat panel that ends the problem of overheating and stagnation and sets a new standard for solar system efficiency and reliability.

The Viessmann Vitosol 200-FM collector features ThermProtect, a patented "intelligent" absorber layer coating that, through temperature-dependent change in its crystal structures, adjusts automatically to changes in sunlight and heat absorption.

Traditional flat panel solar thermal collectors can be prone to steam production due to stagnation, which in turn leads to heat transfer medium degradation. This can be an issue in spring or summer when excess heat from the sun cannot always be used and the panels’ temperature rises. ThermProtect rejects the excess heat back to the environment.

“While there are practical and mechanical ways to design solar systems so that solar thermal stagnation is limited, overheating has been a bug bear to the solar industry,” says Christian Engelke, Viessmann technical director. “ThermProtect on the Vitosol 200-FM is a significant milestone in eradicating this issue and furthers Viessmann, already in the solar thermal market for over 40 years, as a pioneering manufacturer. It makes solar a more attractive proposition for installers and homeowners for whom oversizing is no longer an issue. They can now benefit from a much more reliable renewable technology to add to their homes. We hope this development increases the take-up of solar thermal in the UK.”

Flat plate collector with intelligent absorber layer

The patented coating, developed by Viessmann in partnership with Nancy University, France, prevents further energy absorption when the plate reaches a certain temperature. The absorber coating is based on the principle of "intelligent layers". The coating’s structure changes depending on the collector temperature. Above an absorber temperature of 75 °C the coating increases its emitting of incoming solar radiation and in effect ‘shuts down’.

If the temperature of the collector falls below 75 ° C, the structure of the coating will return to its original state and 95 per cent of the incoming solar energy is absorbed and converted into heat.

The change of the coating’s structure occurs unlimited times and means that the flat panel is never at risk of stagnation.

About Viessmann Limited

The Viessmann Group is one of the leading international manufacturers of heating, cooling and climate control technology. Founded in 1917, the family business maintains a staff of approximately 11,600 employees and generates 2.2 billion Euro in annual group turnover.

With 22 production divisions in 11 countries, subsidiaries and representations in 74 countries and 120 sales offices around the world, Viessmann is an internationally orientated company. 56 percent of sales are generated abroad.