Showing papers on "Solar energy published in 1968"

Calculated efficiencies of practical GaAs and Si solar cells including the effect of built-in electric fields. Technical report

Abstract: Abstract The performance of GaAs solar cells has been calculated as a function of the doping levels, using practical values for the transport parameters. Calculations show that surface recombination is a more probable cause than recombination in the junction region of the poor efficiencies obtained in practice. Electric fields built into the cell by doping gradations may be used to reduce surface losses and produce an efficiency exceeding 20 per cent for a surface recombination velocity of 10 6 cm/sec. This figure allows for the finite resistance of the surface layer, the effect of which is considered in detail for several cases. Results for Si cells are also presented. These are well in accord with the values obtained in practice. For both materials consideration is given to the degradation brought about by particle bombardment.

The Solar Constant Based on New Spectral Irradiance Data from 310 to 530 Nanometers.

Abstract: Solar constant based on spectral irradiance data from spectroradiometer and photoelectric filter radiometer

Acceleration of cosmic rays at the solar-wind boundary.

Abstract: Acceleration of cosmic rays at solar wind boundaries by outward moving magnetic irregularities

Solar X-rays.

Abstract: Solar X-ray data from rocket and satellite-borne equipment, discussing spectrum of quiet corona and active region

On the Solar Energy Balance of Rice Population in Relation to the Growth Stage

Abstract: The utilizing efficiency of solar energy (Eu) in dry matter production of plant population consists of two components: one is the efficiency for absorbing the solar energy by the stand (α) and the other is the efficiency for fixing the absorbing energy for dry matter production (Eφ). With the aim to find out the actual values of these components as well as the utilizing efficiency in a rice population, measurement of the following items was carried out using rice plants, Norin No. 29 which were cultivated in the paddy field at the density of 16 hills/m2 (25×25cm): total incident energy (S), the rate of energy reflection by the canopy (albedo, a), the rate of energy transmittance at the surface of flooding water (t), the rate of energy reflection by the surface of water, the amount of dry matter produced in a certain period (ΔW), the leaf area index (LAI), and the heat of combustion per gram dry matter. Measurements were made continuously from August to October. The results are as follows: 1. The albedo (a) of the rice population before heading stage was almost constant (22%). However, it decreased gradually after heading to reach 18 per cent at maturity. This decrease may be related to the fact that the albedo of ears is lower than that of leaves (table 1). 2. The decrease in the rate of energy transmittance by the canopy according to the advancing growth stage was attributed both to the increase in LAI before heading, and to such changes in the structure of the crop stand as the emergence of ears and decrease in the inclination of leaf-blade after heading (fig. 6, table 1). 3. The efficiency for absorbing the solar energy (α) increased with the growth of rice plants to reach the maximum value (about 70 %) on 30 days after heading. The change of α was closely related to that of t (fig. 4). 4. The heat of combustion per gram of each organ in each growth period was measured by use of a calorimeter. The value, K, was in the following order: Leaf-blade>Leaf-sheath>Root but its variation during the whole growth season was as small as four per cent (table 2). The mean value of K of the whole plant was 3.76 Kcal per gram. 5. The efficiency for fixing the absorbed solar energy (Eφ) was calculated by the following formula: Eφ=(K·ΔW)/(α·ΣS)×100 (%) The value of Eφ for 40 days in total before and after heading varied between 4.1 and 6.9, maximum value being seen at heading stage (table 3). 6. The utilizing-efficiency of incident energy (Eu) is given by the following formula: Eu=(K·ΔW)/(ΣS)×100 (%) The value of Eu fluctuated from 0.8 to 3.7 by growth stage, maximun value being found at heading stage (table 3).

On solar operation of absorption air conditioners

Abstract: Economic exploitation of such a widely distributed resource as solar energy is an exciting challenge to man’s ingenuity; no prospect is more intriguing than solar air conditioning. Techniques of air conditioning are discussed sufficiently to define the compatability with solar conversion methods and to enable calculation of the performance of solar air conditioning cooling cycles. From the various possibilities, absorption refrigerators operated by flat-plate solar collectors are chosen for detailed investigation. After a discussion of the prospects of the system in Australia and a consideration of the environmental conditions, the system is scrutinized with particular emphasis on the refrigerator and the enclosure. Lithium bromide-water refrigerators are shown to have desirable characteristics which can be matched to the solar energy source. Preliminary results of experiments on a residence, air conditioned by a makeshift solar absorption device, are given. The performance is sufficiently encouraging to warrant further work with equipment specifically designed for the application. An economic evaluation of the system reaches the conclusion that, if air conditioning can be justified for residences, solar power will be the cheapest power source for most of tropical Australia.

Thermal radiative and electrical properties of a cadmium sulfide solar cell at low solar intensities and temperatures

Abstract: Thermal radiative and electrical properties of cadmium sulfide solar cell at low simulated solar intensities and temperatures