The article summarizes the results of the operation of the two solar power plants of the SSPS project (Small Solar Power Systems) at Almeria, carried out within the framework of the International Energy Agency. The two power plants were built side by side in order to compare two thermal-electric techniques, one being a distributed collector system (DCS) with arrays of parabolic troughs and the other a central receiver system (CRS) with heliostats concentrating the sunlight onto the top of a tower. Each plant was constructed with a nominal capacity of 500 kWel and was expected to have a net yearly output on the order of 1 GWh.—Only the DCS plant was in operation sufficiently to enable an assessment of possible annual production of electricity. Through extrapolation one finds that the gross output of the built plant was maximal 0.25 GWh with an overall efficiency of 2.3 percent for a plant with 100 percent availability and no malfunctions. Internal electricity consumption correspondingly calculated amounts to 0.11 GWh resulting in only 0.14 GWh yearly net output. Using the experimental values from the CRS plant, it appears that its yearly gross output could have been similar to that of the DCS plant but at higher internal electricity consumption, particularly due to the trace heating of the heat transfer medium (sodium).—The technical reasons for the poor efficiency of the SSPS installation were largely that the solar climate was less favorable then assumed, dirt accumulated on the mirrors at a more rapid rate than foreseen, the nonsolar specific components were badly matched and yielded low efficiencies, and thermal inertia was crucial and almost overlooked in the planning stage.—A detailed loss analysis is presented in the article.

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