PV systems with combined power and heat production

For the above PV/T components, detailed mathematical models have been set and the detailed computer programs have been developed. The mathematical models have been verified by experimental results both for water-heating and air-heating components. After the theoretical-model verification, a multi-parametric analysis has been carried out in order to identify optimal design of the PV/T components. The effect of the influencing parameters on system performance (i.e. efficiency curve) for two basic types of collectors (selective and non-selective absorber) has been analysed. The analysis of energy yields shows that maximum energy yield can be obtained under the following conditions: The absorber absorptance should be as high as possible. The coefficient of emittance of 0.1 produces the best performance for fluid inlet temperatures 30, 50 and 70 deg. C. However, for inlet fluid temperature of 10 deg. C, the best results are achieved with coefficient of emittance of 0.95. A multi-parameter analysis has been carried out using two reference constructions of the PV/T-Wall. The first reference assumes a small light transparency for the solar spectrum and the second reference assumes a light transparency of 80%. Our first strategy was to determine the airflow rate, which leads to maximum annual yield. For the first reference, this rate was found to be 50 m3/h/M"2 and for the second it was found to be 40 m"3/h/m"2. After determination of optimum airflow rates for both systems, another study was performed in order to determine the combination design of parameters, which will lead to best energy yields. Investigation showed that the light transparency of PV wall and the incident angle modifier are most critical parameters of the system