Solar Collectors' Operation Methods Effect on System Efficiency

A control system has been designed for controlling the circulation pumps of a solar collector system depending on weather conditions. To achieve the maximum efficiency of a solar collector system it is necessary to provide the optimum heat flow rate. Decrease in speed of heat flow leads to increasing heat losses in the pipes, especially between the solar collector and the accumulation tank. At the same time, increased flow rate reduces the efficiency of the heat exchanger, so the coolant flow will go at high temperatures thus causing increased energy losses. The operation modes of solar collector systems were investigated at the Institute of Physical Energetics (IPE) solar energy testing polygon for different parameters. The most common types of solar collector operation modes were studied and compared: based on time, on the difference between the input and output temperatures of the heat carrier, on the solar radiation intensity, as well as control techniques in various combinations. The theoretical and practical advantages and disadvantages of using each control technique were analyzed and recommendations given as to the efficiency improvement