Design of a Plant Leaf Area Meter Using PV Cell and Embedded Microcontroller

Dilşad Engin,Mustafa Engin

doi:10.1155/2013/393045

Abstract

This paper presents the development of a solar cell based simple and practical leaf area meter. The system has a silicon solar module which is composed of 6 series connected cells, a light source, and a parabolic reflector with opal glass for diffusing the light. Partial shading effect on PV cell’s voltage and current are evaluated with different geometrical shapes for testing the performance of the model, and the resulting equations for voltage and current changes with respect to measured areas are obtained. The measured current has a good correlation: <svg style="vertical-align:-0.20474pt;width:65.1875px;" id="M1" height="16.1" version="1.1" viewBox="0 0 65.1875 16.1" width="65.1875" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,15.775)"><path id="x1D445" d="M627 18l-10 -26q-79 6 -116 27t-69 76q-41 71 -71 138q-13 29 -27.5 39t-42.5 10h-46l-27 -145q-13 -74 -2.5 -88.5t78.5 -20.5l-6 -28h-271l5 28q66 6 82.5 21.5t30.5 87.5l71 387q12 66 2 78.5t-77 19.5l8 28h233q102 0 147 -29q65 -43 65 -129q0 -69 -45.5 -117
t-115.5 -72q40 -86 66 -133q39 -68 65 -101q28 -37 73 -51zM491 483q0 67 -33.5 101t-91.5 34q-35 0 -51 -10q-13 -8 -20 -48l-45 -245h49q71 0 113 28q79 52 79 140z" /></g> <g transform="matrix(.012,-0,0,-.012,11.013,7.613)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g> <g transform="matrix(.017,-0,0,-.017,22.062,15.775)"><path id="x3E" d="M512 230l-437 -233v58l378 199v2l-378 200v58l437 -233v-51z" /></g><g transform="matrix(.017,-0,0,-.017,36.749,15.775)"><path id="x30" d="M241 635q53 0 94 -28.5t63.5 -76t33.5 -102.5t11 -116q0 -58 -11 -112.5t-34 -103.5t-63.5 -78.5t-94.5 -29.5t-95 28t-64.5 75t-34.5 102.5t-11 118.5q0 58 11.5 112.5t34.5 103t64.5 78t95.5 29.5zM238 602q-32 0 -55.5 -25t-35.5 -68t-17.5 -91t-5.5 -105
q0 -76 10 -138.5t37 -107.5t69 -45q32 0 55.5 25t35.5 68.5t17.5 91.5t5.5 105t-5.5 105.5t-18 92t-36 68t-56.5 24.5z" /></g><g transform="matrix(.017,-0,0,-.017,44.909,15.775)"><path id="x2E" d="M113 -12q-24 0 -39.5 16t-15.5 42q0 24 16 40.5t40 16.5t40 -16.5t16 -40.5q0 -26 -16 -42t-41 -16z" /></g><g transform="matrix(.017,-0,0,-.017,48.785,15.775)"><path id="x39" d="M244 635q90 0 143 -72t53 -177q0 -133 -65 -229.5t-171 -139.5q-79 -32 -140 -32l-5 30q109 18 185 91t101 186l-68 -36q-29 -16 -60 -16q-79 0 -129 51.5t-50 130.5q0 80 57 146.5t149 66.5zM228 602q-52 0 -78 -45.5t-26 -98.5q0 -69 36.5 -115.5t97.5 -46.5
q53 0 90 28q4 31 4 66q0 51 -9.5 95.5t-39 80.5t-75.5 36z" /></g><g transform="matrix(.017,-0,0,-.017,56.944,15.775)"><use xlink:href="#x39"/></g> </svg> for regularly shaped leaves and <svg style="vertical-align:-0.20474pt;width:65.1875px;" id="M2" height="16.1" version="1.1" viewBox="0 0 65.1875 16.1" width="65.1875" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,15.775)"><use xlink:href="#x1D445"/></g> <g transform="matrix(.012,-0,0,-.012,11.013,7.613)"><use xlink:href="#x32"/></g> <g transform="matrix(.017,-0,0,-.017,22.062,15.775)"><use xlink:href="#x3E"/></g><g transform="matrix(.017,-0,0,-.017,36.749,15.775)"><use xlink:href="#x30"/></g><g transform="matrix(.017,-0,0,-.017,44.909,15.775)"><use xlink:href="#x2E"/></g><g transform="matrix(.017,-0,0,-.017,48.785,15.775)"><use xlink:href="#x39"/></g><g transform="matrix(.017,-0,0,-.017,56.944,15.775)"><path id="x35" d="M153 550l-26 -186q79 31 111 31q90 0 141.5 -51t51.5 -119q0 -93 -89 -166q-85 -69 -173 -71q-32 0 -61.5 11.5t-41.5 23.5q-18 17 -17 34q2 16 22 33q14 9 26 -1q61 -50 124 -50q60 0 93 43.5t33 104.5q0 69 -41.5 110t-121.5 41q-53 0 -102 -20l38 305h286l6 -8
l-26 -65h-233z" /></g> </svg> for irregularly shaped ones. The resulting voltage and current measurements are then fed to an ARM Cortex M3 core 32-bit LM3S1968 microcontroller via a voltage and current measuring unit. The calculated leaf areas from the obtained area-current relations are shown on an OLED graphics display. The whole system is easy to use and user-friendly. The leaf area measurements are confirmed by comparing the results with measurements of grid counting method.

Full Text