Collectors have an average degree of efficiency of between 50 and 60 percent. The thermal behaviour of solar collectors is very well known, but our understanding of the interior climate of glass collectors and their long-term behaviour is still insufficient. It is now necessary to develop and test new lighter and thinner collectors that can be more readily integrated.
Solar collectors with a low concentration (1 to 10) are also suitable for solar energy use at between 60° and 100° C, and for this reason special optical and thermal studies are necessary in this area.
The service life of collectors is another aspect that needs to be researched.