Solar radiation variability

Labed S., Lorenzo E., The impact of solar radiation variability and data discrepancies on the design of PV systems. Renewable Energy 2004 29 1007-1022. 

The amount of solar radiation that reaches any point on the ground is extremely variable. As it passes through the atmosphere, 25 to 50 percent of the incident energy is lost due to reflection, scattering nr absorption. Even on a cloud-free day about 30 percent is lost, and only 70 percent of 1,367 W/nf, or 960 W/m, is available at the earth s surface. One must also take into account the earth s rotation and the resultant day-night (diurnal) cycle. If the sun shines 50 percent of the time (twelve hours per day, every day) on a one square meter surface, that surface receives no more than (960 W/m ) X (12 hours/day) X (365 days/year) =... 

The concept of global radiative equilibrium is useful in identifying the various factors that govern climatic variability. At radiative equilibrium, the flux of solar radiation absorbed by the planet equals the flux of infrared radiation to space. That is. 

This chapter summarizes climate projections presented by the recent Fourth Assessment Report (AR4) of the IPCC, both for the global scale and for the so-called European and Mediterranean region. Besides the IPCC projections, other results regarding the Mediterranean area will be reviewed as well. The emphasis will be mostly placed on temperature and precipitation projections, while other variables, such as wind, solar radiation, or sea level, will not be commented in depth. Some attention will be paid to methodologies used to develop projections, and the corresponding uncertainties will be commented. In general, projections will be given for the end of the current century. 

Significant economies of computation are possible in systems that consist of a one-dimensional chain of identical reservoirs. Chapter 7 describes such a system in which there is just one dependent variable. An illustrative example is the climate system and the calculation of zonally averaged temperature as a function of latitude in an energy balance climate model. In such a model, the surface temperature depends on the balance among solar radiation absorbed, planetary radiation emitted to space, and the transport of energy between latitudes. I present routines that calculate the absorption and reflection of incident solar radiation and the emission of long-wave planetary radiation. I show how much of the computational work can be avoided in a system like this because each reservoir is coupled only to its adjacent reservoirs. I use the simulation to explore the sensitivity of seasonally varying temperatures to such aspects of the climate system as snow and ice cover, cloud cover, amount of carbon dioxide in the atmosphere, and land distribution. 

The solar radiation had a certain variability, although in general it took values around 200-300 W/m2... 

Find the structure parameters x and the properties y of a given compound at room temperature and pressure. What are the properties of the compound at elevated or lowered temperatures and pressures, as well as of other environmental variables, such as electromagnetic field and solar radiation, so that this search can be written as y = f x, T, P)1... 

An analysis of the solar distillation process shows that performance is remarkably insensitive to all variables except solar radiation rate. As atmospheric temperature changes, basin and cover temperatures move similarly, so that their difference remains... 

Regression analysis in time series analysis is a very useful technique if an explanatory variable is available. Explanatory variables may be any variables with a deterministic relationship to the time series. VAN STRATEN and KOUWENHOVEN [1991] describe the dependence of dissolved oxygen on solar radiation, photosynthesis, and the respiration rate of a lake and make predictions about the oxygen concentration. STOCK [1981] uses the temperature, biological oxygen demand, and the ammonia concentration to describe the oxygen content in the river Rhine. A trend analysis of ozone data was demonstrated by TIAO et al. [1986]. 

Different variables affect the intensity of solar radiation. As the emission of solar radiation is considered constant, the summer sun is stronger than the winter sun, the sun on the equator stronger than the sun in Lapland, and the midday sun burns more than the afternoon sun. Eog does not slow down UV penetration, but urban pollution is, on the contrary, a powerful sunblock because of the presence of aromatic hydrocarbons, which make excellent UV blocks. Altitude in itself has less influence than the angle of incidence, but snow, on the other hand, reflects 85% of UV rays, whereas dry sand only reflects 17%, water 5% and grass 2%. Therefore, places lying between snow-covered mountains on a very sunny day are particularly dangerous. 

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