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%.

Figure 17 An 18 000 m² array of collectors feeding a district heating system at Marstal in Denmark

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?