General dimensional aspects

In Hungary based on its meteorological conditions, only solar collectors cannot produce the all year round thermal need for the various fields of use. Therefore the solar collector systems are utilized parallel with the traditional energy carrier heat producers. When designing the dimensions of the solar collector the most important aim is to realize which size is the optimal system, and in what proportion it can meet the heat need for a given task. The quotient of the heat need covered by the collectors, and the completely needed heat need is called the solar partial proportion.

The other important aspect of the solar collectors is the system efficiency, which is the quotient of the utilized solar radiation by the collector, and the solar radiation arriving to the surface of the collectors.

Drawing the two characteristics into a chart, we can realize that their direction is just opposite. The systems with low solar partial proportion work with high efficiency, though high solar partial proportion can only be reached by low system efficiency. The optimal solar partial proportion depends on several factors. In the case of small systems producing warm water for use, or family houses the 50-70% efficiency most probably can be reached. In the case of bigger systems the lower, 20-50% value should be aimed at, the saving is still significant. In both cases the all year round efficiency of the solar collector, the trustable operation, and the refund of the investment expenses are important.

                                                              Heat amount of collectors

          Solar partial proportion =--------------------------------------------------------         

                                                                  Complete heat need

                                                                 Utilized solar radiation

          System efficiency =  -----------------------------------------------------------

                                            The utilizable heat amount by solar collector systems

Globális Yearly sum of overall radiation in Hungary [kWh/m²/year]

Average daily value of the solar radiation energy arriving to horizontal surface [kWh/m²/day]

More accurate dimension setting of a solar collector can be done through a computer simulation software, which is able to make all the complex calculations, of collectors dimensions depending on several factors, after given all the parameters found in natural systems.

Without a computational method it is difficult to design the dimensions of solar collector systems. Simplifying formula, maps or monograms exist, with which approaching pre-measurements can be made.

Complete power of radiation, arriving to southbound, 35° leaned surface, based on the calculation of average value of a day of months: [Wh/m²]

Complete power of radiation, arriving to southbound, 35° leaned surface

Complete power of radiation, arriving to southbound, 45° leaned surface, based on the calculation of average value of a day of months: [Wh/m²]

Complete power of radiation, arriving to southbound, 45° leaned surface