The trough collector is relatively insensitive to rises in the absorber fluid temperature. This is
the consequence of its small receiver surface area, which leads to low heat losses. The trough‘s
high energy yield results also from its tracking system: the trough already catches the sun in
the morning until the late evening. At temperatures above 65°C the parabolic trough collector
therefore yields more energy than a flat plate collector. The highest yield up to 150°C can be
achieved with a vacuum tube with CPC because it has low thermal losses and uses the global
radiation.
Finally decisive are the costs per kilowatt-hour for solar heat. Included in the costs are the
investment and installation costs of the collector field and the operation and maintenance costs
(Table 1). Because thermal losses increase with collector temperature, the heat price strongly
depends on the mean fluid temperature (Figure 14).