Great Solar Product Shame About The Budget

New solar thermal panels end stagnation with unique, automated ‘temperature shutdown’ coating

The word stagnation brings anybody involved with solar thermal shudder, frankly the shudder is twofold with regard to heat issues and also UK government having a total inability to keep to its promises. The budget favours nuclear power and not catching rays from the sun.


Christian Engelke, Viessmann technical director pictured above.

Going back a decade the solar thermal industry had a simple grant scheme backed by the Low Carbon Buildings Programme and then it was scrapped at the time of the crash and we all had to wait for RHI to replace the LCB-Programme. Now RHI and solar thermal have parted company.

It seems as though the thermal ship has sailed just as Viessmann decide it is time to bring 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’.


Nancy University, France Source Wikipedia.

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.

I love it but wonder if it will ever see the light of day (excuse the pun) and we can only live in hope for some sort of subsidy to help the industry back on its feet.

This manufacturer might sell EUR 2 billion but sadly not much of this comes from UK solar sales and its a shared effort from 120 global offices.

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