This limits the system size. Systems in the medium range of 100–500 m2 are common in Austria, with around eight times more systems built in this range between 2010 and 2016 compared to large-scale systems . Recently, combining large-scale solar thermal systems with heat pumps has become more common.
China, Germany and Austria have a broader variety of large-scale solar thermal applications including solar process heat, partly due to incentive schemes based on installation cost of plants rather than market-based instruments like in Denmark.
The market potential of large-scale solar thermal systems depends on the availability, price and environmental impact of competing technologies and heat sources. Coal, natural gas and oil are the prevailing fossil fuels in DH networks and industrial processes both worldwide and in Denmark, China, Germany and Austria .
Another typical business strategy for large-scale solar thermal systems in Germany is the change from fossil fuels to renewable energies in DH systems. One regulatory reason for this effort is the reduction of the primary energy factor of the DH network.
Large-scale solar thermal plants can be used in a broad variety of industrial processes but this market is much smaller. Realized plants are providing heat for brewing, an absorption chiller in steel production, greenhouses, cleaning processes in food production and car washing .
The most common application of large-scale solar thermal systems is heat supply to DH networks and local heating networks with residential, commercial and public buildings, which makes up 88% of the total installed and operated capacity. Solar process heat, which is mainly used in the mining, textile and food industry, amounts to 12% .