Engineering On The Edge

Possibly the best possible alternative energy solution for automobiles comes from a free and abundant source: the sun. Think about how fantastic it would be to own an automobile powered at least in part by photovoltaic cells. Carbon emissions? Nope. Stopping to recharge batteries? Negative.

The American Solar Challenge is a yearly collegiate competition in which contestant universities race across eight states in eight days. The vehicles are allowed two hours at dawn and dusk to recharge. The rest of the trip is powered by stored energy and continued solar absorption.

Oregon State University's solar-powered vehicle, the Phoenix. Courtesy of OSU.

This year, Keithley Instruments lent a helping hand to Oregon State University’s (OSU) team with the donation of a Model 2440 5A SourceMeter to analyze and troubleshoot mono-crystalline silicon solar modules. The donation led to a 50% increase in the speed of OSU’s solar vehicle, the Phoenix.

To get the most out of the vehicle, OSU needs parametric data from each of the solar modules on thePhoenix. This data allows them to arrange sub-arrays on the car to provide the most efficient flow of energy. The SourceMeter is used to record each module’s overall and maximum power output, using an I-V curve tracing technique.

“The data we obtained on maximum power output, open-current voltage, short-circuit current, maximum voltage, and maximum current let us detect problems like shorted and cracked cells, as well as to determine the best sub-array location for each module to maximize overall power output or to reject a module outright,” said Kathy Han, the OSU manager and lead for the body and co-lead for the solar module team.

“Before we had access to the Model 2440, we had problems with one of our previous solar arrays that used solar cells that had been laser-cut from the front side, which we now know produces some melting of the p/n junction. This caused internal shorts and increased internal resistance in the cells,” Han added.

OSU finished in sixth place in the American Solar Challenge and in fifth place in the Formula Sun Grand Prix.

Below you’ll find a video that discusses thePhoenix.

Source: Keithley Instruments