Characteristics solar constant

The operation of a photovoltaic system is governed by the current-voltage characteristic curves of the photovoltaic module. Such a set of curves, for different values of the incident solar irradiance and constant photovoltaic module temperature, is shown in Figure 2.4. The curves consist of two parts. In the first part the photovoltaic module behaves as a constant-current source, with amplitude proportional to the solar irradiance level. In the rest of the curve, current decays... 

Fig. 1 Matching of current-voltage characteristics of solar cell and electrolyzer (a) at constant light power density 1, 2, 3 - characteristics of solar cell at Ng = 1,2, and 4 (at Sj = const) 4 - characteristic of electrolyzer (Ng = 1) o - maximum power point (MPP) dashed line shows the locus of maximum cell output power at the given radiation power density (b) at varying radiation power density 1 , 2, 3, -characteristics of solar cell dashed line - locus of MPP hatched area - variations of MPP in the most probable limits of variation of the light power density and temperature 4 - characteristic of electrolyzer.

Principles of simulation have been elaborated by Carpetis [22] who introduced the current-voltage characteristic of the solar cell in an implicit form, O (I, Vj, T, J) = 0 where Ig and Vg are the cell output photocurrent and voltage respectively, T is the cell temperature, and J is the solar radiation intensity. Besides four variables the function O contains also five constants which are to be determined from five independent sets of experiments. 

Both mammals and birds are homeotherms, which means that they attempt to keep their body temperature constant. Animals produce heat continuously and, if they are to maintain a constant body temperature, must lose heat to their surroimd-ings. The two main routes of heat loss are the so-called sensible losses by radiation, conduction and convection from their body surface, and evaporative losses of water from the body surface and lungs (2.52 MJ/kg water). The rate at which heat is lost is dependent in the first instance on the difference in temperature between the animal and its surroimdings for farm animals, the rectal temperature, which is slightly lower than the deep body temperature, lies in the range 36-43 C.The rate of heat loss is also influenced by animal characteristics, such as insulation provided by the tissues and coat, and by environmental characteristics, such as air velocity, relative humidity and solar radiation. In effect, the rate of heat loss is determined by a complex interaction of factors contributed by both the animal and its environment. 

The textile with embedded flexible solar cells overcomes the aforementioned technical problems. According to a first aspect, its subject matter is a reliable photovoltaic composite, employed in particular for solar protection, which includes at least one flexible photovoltaic panel and at least one textile panel on the outside face, on which the said photovoltaic panel is laminated by means of a first connecting layer. In a characteristic manner, in the direction transverse to that in which it is to be rolled and at any level of the photovoltaic panel, the said composite is of more-or-less constant thickness, including one or more reduced thickness zones, where the said reduced thickness corresponds to the thickness of the textile panel possibly covered with a film on its inside face. This particular arrangement is used to prevent the formation of folds in the composite, whether during the rolling operation or in the deployed position. 

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