evaluating effect of insolation on pv cell output using

Journal <strong>of</strong> Engineering, Science and Management EducationThe Zenith Angle (Z) is the angle from the observer's zenithpoint to the suns' position in the sky. In order to calculate thezenith angle latitude, solar declination angle and hour anglemust be consideredZenith Angle (Z)ZenithZSurface <strong>of</strong> the EarthFig. 6 Zenith Angle The solar constant is the average amount <strong>of</strong> energy strikingone square meter (perpendicular to the suns' rays) eachsecond at the top <strong>of</strong> the earths' atmosphere. The satellite2measured solar constant is 1366 W/m . Of this energyreaching the top <strong>of</strong> the atmosphere as much as 70% can beabsorbed & reflected by the atmosphere. Solar <strong>insolation</strong>is the amount <strong>of</strong> energy received by the sun at the earths'2surface. On a clear day ~1000 W/m reaches a surfaceperpendicular to the incoming radiation. This energyvaries due to the angle <strong>of</strong> the incoming radiation and againcloud cover.Equations for Solar <strong>insolation</strong>S * cos ZSuns 1000whereZ cos 1 (sinsincoscoscos H )andH = 15O * (Time -12)Solar DeclinationAngles for the Northern HemisphereVernal Equinox Mar. 21/22Summer Solstice Jun. 21/22Autumnal Equinox Sept. 21/22Winter Solstice Dec. 21/22MAT LAB PROGRAM AND RESULTSun =0 O = +23.5 O =0 O = -23.5 OThe following MATLAB program calculates the I-Vcharacteristic <strong>of</strong> solar cell (with shunt resistance) taking<strong>insolation</strong> as a variable. This script calculates the outputcurrent corresponding to the required output voltage providedas the input. The <strong>effect</strong> <strong>of</strong> shunt resistance and the <strong>effect</strong> <strong>of</strong>variation <strong>of</strong> solar <strong>insolation</strong> are also considered. Solar<strong>insolation</strong> at a given place is calculated by taking intoconsideration the latitude <strong>of</strong> the place <strong>of</strong> incidence, time andday <strong>of</strong> the year. The <strong>effect</strong> <strong>of</strong> temperature variation with thepassage <strong>of</strong> time <strong>of</strong> day is also taken into account.Although thevariation <strong>of</strong> temperature as well as solar declination angle isassumed to be linear. The result is calculated for latitude =Oth23.2667 , for 15 <strong>of</strong> May function I = panelvarshunt(V,TeC)%PANELVARSHUNT - File to calculate output currentcorresponding% to required output voltage given as input.%Call syntax: I = panelvarshunt(V,TeC);%Input: V = output voltage required (may be a vector),% TeC = surrounding temperature in degree Celsius% (may be a vector)% latitude,time in 24 hr format (may be avector),date,month.%Output: I = output current corresponding to voltage V%-------------------------------------%% Constantsk = 1.38e-23; % Boltzman's constq = 1.60e-19; % charge on an electronn = 1.2; % diode quality factorVg = 1.1; % band gap voltage, 1.1eV for Si.Ns = 36; % No. <strong>of</strong> cells in a arrayRs = 0.008; % series resistance <strong>of</strong> cell(in ohms)Rsh = 200; % shunt resistance <strong>of</strong> cell(in ohms)S = 1000; % solar <strong>insolation</strong> on a clear sunny dayd2r = pi/180; % converts degree to radians%% Inputslatitude = 23.2667;time = linspace(6,18,50);date = 15;month = 5;%% Calculation <strong>of</strong> sunsswitch (month)case {1}dateeq = 12 + date;case {2}dateeq = 12 + 31 + date;case {3}dateeq = 12 + 31 + 28 + date;case {4}dateeq = 12 + 31 + 28 + 31 + date;case {5}dateeq = 12 + 31 + 28 + 31 + 30 + date;case {6}if(date

Journal <strong>of</strong> Engineering, Science and Management Educationcase {10}dateeq = 11 + 31 + 31 + 30 + date;case {11}dateeq = 11 + 31 + 31 + 30 + 31 + date;case {12}if(date = 6 && date >= 21) && (month

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