Solar energy availability

The thermal solar farm operation will be optimum if it efficiently responds to both the variation in solar energy availability (insolation) and to both equipment limitations and market conditions. In order to do that, one of the first requirements is to determine the efficiency curves for each combination of equipment blocks as a function of load and then operate the system at that point. 

Munroe, M. and Shepherd, W., "Assessment of Solar Energy Availability in Different Regions of the Solar Spectrum," Solar Energy, 26, 41 (1981). 

The Earth s elliptical orbit causes the distance between the Earth and the Sun (the Earth s radius vector) to vary by 3.39% from perihelion (closest) to aphelion (farthest). These variations in distance cause the intensity of solar radiation at the top of the atmosphere to vary as 1/R2, where R is the radius vector. Thus the solar input at the top of the atmosphere varies from 1414 Wm 2 (in December) to 1321 Wm 2 (in July). Additional variations in solar intensity, or brightness, result from the solar sunspot cycle, and even solar oscillations. These slight variations in the solar output are usually accounted for in the calculation of solar energy available at the top of the atmosphere, or the total extraterrestrial solar radiation, referred to as ETR. The ETR has only been monitored from space since the early 1970 s, or almost three solar sunspot cycles. Excellent histories of ETR measurements and analysis are provided in Frohlich3 and Gueymard.4... 

Fig. 8. aheat, the fraction of solar energy available below the minimum sensitizer insolation frequency used to drive charge transfer, Vmm.3 The aheat is determined as 1- Pm, with Prei = / max/Psun, and using values of 7 max summarized in Fig. 7. The available incident power below Vmin will be aheatPsun. The bandgaps of various semiconductors are superimposed as vertical...

Total solar energy available on the acre during growing season Photosynthetic efficiency of com plants, i.e., percent of available energy used in photosynthesis Energy equivalent of earth s carbon production Mean solar radiation Photosynthetic efficiency of the world... 

The number 5 x 10 erg/year provides a reasonable resource estimate for a discussion of solar energy availability over the entire planetary sttrface. 

On the basis of the long-term collector efficiency, the collector surface necessary for the operation of the dryer can be determined. Because the instantaneous efficiency of the collector is over one part of operation time greater than the long-term efficiency, the energy utilized by the collector over this period is greater than the necessary value. The surplus energy can be stored for the period when there is no solar energy available. In cheap, simple construction dryers without... 

The future of chemurgy is intercoimected with the economic future of energy, environment, and food. Several scenarios exist for future sources of energy and materials. Some involve the use of nuclear or solar energy (qv) leaving coal and oil available for chemicals and transportation fuels. Some involve... 

Solar cells the difference between conduction and valence band chemical potentials is the available output voltage of a solar cell. Light creates the chemical potential difference simply by boosting a population of electrons from the valence band into the conduction band (see Photovoltaic cells Solar energy). 

Nuclear energy could be a compact source for application in an ion engine, but no practical devices have yet been constructed. Nuclear energy would be necessary for the ion drive of an interstellar mission for which solar energy would not be available. 

Many further solar energy developments and demonstrations took place m the first half of the twentieth century. However, only one solar technology survived the commercial competition with cheap fossil fuels. That exception was solar water heaters that were widely used in Japan, Israel, Australia and Florida, where electricity was expensive and before low-cost natural gas became available. 

When solar energy is available the diluted solution is regenerated to its original concentration in a regenerator, at temperatures of 70-80 °C. At this temperature water evaporates from the desiccant solution and is taken to the ambient by an air flow through the regenerator. The Lithium Chloride does not evaporate. It remains in the solution and in the cycle. Heat recovery for the air flow is used to keep up the thermal coefficient of performance. 

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