Heat pipes are inserted into the aluminium absorbers forming assemblies, which in turn are inserted into the glass tubes. The tubes are made of borosilicate glass which is strong and has a high transmittance for solar irradiation. In order to reduce the convection heat loss, glass tubes are evacuated to vacuum pressure of <10-5 mbar. Sunda uses a patented technique employing high heat and pressure to insure stable glass-to-metal vacuum seals. In order to keep the stability of the vacuum for a long time, a barium "getter" is used. Through evacuating air out of the glass tube the absorber material and the selective coating are protected from corrosion and other environment influences. This ensures a lifetime of at least 15 years without loss of efficiency.
Advantages of the Technology
Resistance in harsh environments, e.g. against corrosive materials, vibrations, serious temperature fluctuations
Long-term, reliable protection of the packaged component