7 Solar district heating
Considerable economies can be achieved when solar collectors are purchased and erected in bulk for large projects.
Since the 1980s there has been a steady stream of construction of large arrays of solar collectors for district heating systems in mainland Europe, mainly in Denmark, Sweden and Germany. The arrays can be very large. The 18 000 m2 array shown in Figure 18 includes a 12 100 m3 heat store and supplies 30% of the annual heat requirement for a district heating system supplying 1600 households.
Since the photograph was taken the array has been increased by a further 15 000 m2 with a further 75 000 m3 of storage, increasing the share of heat production for the district heating system to 55%.
Marstal is not the largest such facility in Denmark, which boasts four larger ones that entered service between 2009 and 2016 (SDH, 2016).
In what other ways can the Sun’s warmth be harnessed?