Keywords: atmosphere layers, photovoltaics, solar exergy, solar irradiation, thermodynamics, exergy efficiency, PV cells, photovoltaic cells, temperature changes, heat losses
Vertically solar irradiation exergy changes in the different layers of atmosphere
The thermodynamic characteristics of solar irradiation in the different layers of atmosphere are investigated from a perspective based on exergy. It is known that the main energy source of photovoltaic (PV) cells, solar power satellites and solar thermal devices is the solar irradiance incident on modules. To evaluate the exergy efficiency of PV cells, therefore, firstly we need the exergy of the total solar irradiation for considered locations. In this paper, firstly changes of temperature and solar irradiation in the vertical structure of the atmosphere would be considered and after that solar exergy values for different altitudes are estimated. Especially on the upper layers of the atmosphere, solar irradiation potential is higher than in the lower levels, but considering, higher temperature gradient between stratosphere and thermosphere causes important heat losses in PVs along with efficiency decreasing. In addition, vertically temperature gradient decreasing in the troposphere causes increasing solar exergy values.