The temperature requirements of solar industrial process heat applications range from 60
C
to 260
C. The characteristics of medium to medium-high temperature solar collectors are
given and an overview of efficiency and cost of existing technologies is presented. Five col-lector types have been considered in this study varying from the simple stationary flat-plate to
movable parabolic trough ones. Based on TRNSYS simulations, an estimation of the system
efficiency of solar process heat plants operating in the Mediterranean climate are given for the
different collector technologies. The annual energy gains of such systems are from 550 to 1100
kWh/m
2
a. The resulting energy costs obtained for solar heat are from 0.015 to 0.028 C£/kWh
depending on the collector type applied. The viabilities of the systems depend on their initial
cost and the fuel price. None of these costs however is stable but change continuously
depending on international market trends and oil production rates. The costs will turn out to
be more favourable when the solar collectors become cheaper and subsidisation of fuel is
removed. Therefore the optimisation procedure suggested in this paper should be followed in
order to select the most appropriate system in each case.
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