District and block heating applications offers good conditions for the use of solar thermal for existing buildings and there are a number of demonstration plants with ground-mounted as well as roof-mounted collector arrays.

A major advantage is that the solar plant can be of considerable size that leads to lower specific costs. The largest solar district heating plant comprises 18.300 m² of collector area (~10 MW thermal capacity).

The main barriers to growth are low alternative fuel costs and lack of confidence for solar heating in thermal utilities. Once cost-effective seasonal heat storage will be widely available, large-scale applications will become more competitive, resulting in a strong increase of the potential for solar thermal.

Further information:

• Jan-Olof Dalenbäck of Chalmers University, Sweden, maintains an excellent overview of large-scale solar thermal systems - most of which are used for district heating.