ENGR 1181 First-Year Engineering Program College of Engineering Engineering Education Innovation Center First-Year Engineering Program Solar Cell Lab

ENGR 1181 First-Year Engineering Program Solar Cells – Current Applications Calculators that never need batteries Emergency road signs or call boxes, on buoys, even in parking lot lights Satellites where they are used to power the electrical systems Yard Lights Residential Limited commercial Solar Cells

ENGR 1181 First-Year Engineering Program Solar Cell Lab - Materials Silicon (not doped) is basically an insulator (with 4 valence electrons, all used in bonding crystal lattice => no 'free electrons) Solar Cell consists of 2 differently doped semiconductors layers (silicon) N-doping introduces free 'electrons' (introduce impurity into lattice with 5 valance electrons => 1 free electron per atom) P- doping introduces free 'holes' (introduce impurity into lattice with 3 valance electrons => 1 free 'hole' per atom) POSITIVE NEGATIVE

ENGR 1181 First-Year Engineering Program Solar Cell Lab – Electrical Concentration difference of holes and electrons – The important fact to note on the next slide is that when N and P doped materials are layered, a surplus of positive and negative charge carriers are produced so that when photons(light) hit the solar cell these additional charge carriers, which were initially in equilibrium, now cause an external voltage whose value is dependent upon the employed materials.

ENGR 1181 First-Year Engineering Program Solar Cell Lab - Electrical For more information refer to: cell.htm Depletion Region Sunlight or Light Source In Solar Cell Lab, Load = Resistor

ENGR 1181 First-Year Engineering Program P. 6 Solar Cell Lab - Device

ENGR 1181 First-Year Engineering Program Solar Cell Lab - Characteristics Energy generated by the solar cell is –Proportional to the intensity of the incident light –Dependent upon the load applied to the solar cell –Temperature dependent

ENGR 1181 First-Year Engineering Program Solar Cell Lab - Evaluation Advantages –Energy source is FREE (sun) –No emissions (earth friendly) –No moving parts (low maintenance) Disadvantages –Technology is presently very expensive –Low power conversion efficiency (5 – 17 %) –Intensity of light source impacted by geographical location and local weather conditions –Energy source available for limited time (daylight)

ENGR 1181 First-Year Engineering Program Solar Cell Lab - Schematic red banana plug lead ( resistive lead – negligible impact ) Light Source Indicates probe ends black banana plug lead ( resistive lead – negligible impact )

ENGR 1181 First-Year Engineering Program Solar Cell Lab Setup

ENGR 1181 First-Year Engineering Program Solar Cell Lab Circuit Diagram Wire connections Resistor Board Solar Cell DMM

ENGR 1181 First-Year Engineering Program Solar Power Conversion Efficiency V

ENGR 1181 First-Year Engineering Program Solar Cell Output as a function of Incident Light Angle

ENGR 1181 First-Year Engineering Program Solar Cell - Procedure Please note that you should use the on- line version of the Solar Cell Procedure in the lab since it is in color and thus is much easier to view and understand the various connections. You can use your hard copy as a reference when you are writing your memo.

ENGR 1181 First-Year Engineering Program Solar Cell – Procedure, one last hint Very slight changes of the solar cell location in the x and y directions are needed to maximize the voltage reading and thus the incident light! x y Voltage reading