D., “ Low Light Performance of Mono-Crystalline Silicon Solar Cells”, in 4th World Conference on Photovoltaic Energy Conference, Waikoloa, HI, 2006, pp. Bunea, Wilson, K., Meydbray, Y., Campbell, M., and Ceuster, D. Consequently, under cloudy conditions, a solar cell with a high shunt resistance retains a greater fraction of its original efficiency than a solar cell with a low shunt resistance 1. When these two resistances are similar, the fraction of the total current flowing through the shunt resistance increases, thereby increasing the fractional power loss due to shunt resistance. As the light intensity decreases, the bias point and current through the solar cell also decreases, and the equivalent resistance of the solar cell may begin to approach the shunt resistance. At low light levels, the effect of the shunt resistance becomes increasingly important. Solar cells experience daily variations in light intensity, with the incident power from the sun varying between 0 and 1 kW/m 2. As losses due to short-circuit current depend on the square of the current, power loss due to series resistance increases as the square of the concentration. The efficiency benefits of concentration may be reduced by increased losses in series resistance as the short-circuit current increases and also by the increased temperature operation of the solar cell. The cost of a concentrating PV system may be lower than a corresponding flat-plate PV system since only a small area of solar cells is needed. Where X is the concentration of sunlight.įrom the equation above, a doubling of the light intensity (X=2) causes a 18 mV rise in V OC. Therefore, under concentration, V oc increases logarithmically with light intensity, as shown in the equation below Instead, the efficiency benefits arise from the logarithmic dependence of the open-circuit voltage on short circuit. However, this effect does not provide an efficiency increase, since the incident power also increases linearly with concentration. The short-circuit current from a solar cell depends linearly on light intensity, such that a device operating under 10 suns would have 10 times the short-circuit current as the same device under one sun operation. Concentrators have several potential advantages, including a higher efficiency potential than a one-sun solar cell and the possibility of lower cost. Many workplanes are not perpendicular to the direction of light intensity, which is why calculating light level at a point is useful for such applications. The incident sunlight is focused or guided by optical elements such that a high intensity light beam shines on a small solar cell. ConcentratorsĪ concentrator is a solar cell designed to operate under illumination greater than 1 sun. The series resistance has a greater effect on performance at high intensity and the shunt resistance has a greater effect on cell performance at low light intensity. Earthquakes spread out, so they do less damage the farther they get from the source.The effect of concentration on the IV characteristics of a solar cell. The intensity of the light is related to the number of photons that pass by us per second, while the energy per photon is dependent upon its frequency (or wavelength, since wavelength and frequency of light are related by the formula c, where c, the speed of light in a vacuum, is a constant and equal to 3.0 x 10 8 m/s). Sunlight, for example, can be focused to burn wood. Waves can also be concentrated or spread out. Problem 1: Calculate the intensity of a wave whose power is 25 KW and the area of cross-section is 35×10 6 m 2 Answer: Known measures are, P 25 KW 25×10 3 W, A 35×10 6 m 2. For example, the longer deep-heat ultrasound is applied, the more energy it transfers. Let us discuss the questions related to intensity. The energy effects of a wave depend on time as well as amplitude. In fact, a wave’s energy is directly proportional to its amplitude squared because Because work \(W\) is related to force multiplied by distance (\(F_x\)) and energy is put into the wave by the work done to create it, the energy in a wave is related to amplitude. The larger the displacement \(x\) the larger the force \(F = kx\) needed to create it. More quantitatively, a wave is a displacement that is resisted by a restoring force. To find a more precise relationship, we fit a curve to our points and the best equation to represent our data was Illumination A/(Distance)2+B where A. Large ocean breakers churn up the shore more than small ones. Loud sounds have higher pressure amplitudes and come from larger-amplitude source vibrations than soft sounds. Large-amplitude earthquakes produce large ground displacements. The amount of energy in a wave is related to its amplitude. (credit: Petty Officer 2nd Class Candice Villarreal, U.S. The Richter scale rating of earthquakes is related to both their amplitude and the energy they carry. \): The destructive effect of an earthquake is palpable evidence of the energy carried in these waves.
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