SPANDEX FRR

Mission Goal We aim to measure solar panel efficiency as a function of altitude. We would like to determine if the lower temperature and thinner air of the upper atmosphere have an effect on the efficiency of a PV cell. Science Objectives We seek to determine the efficiency of the solar cell, discover what effect varying temperatures have on the efficiency, and to discover if the Sun’s radiation in the upper atmosphere has a different effect from the radiation in the lower atmosphere. Technical Objectives We will construct a well-insulated box, voltmeter, and MPP (maximum power point) tracker. We also want to keep the payload level at all times.

Background and Requirements

P out = V^2 / R Efficiency = P out / P in Area of cell = cm^2 The solar cell data sheet claims that the cell should put out 1.55 watts at 25 degrees Celsius with an irradiance of 1000 W/m^2 shining directly on it We expect a max of 1.84 W at -60 degrees Celsius with the sun at 21 degrees from its normal with an irradiance measurement of 1000 W/m^2. We expect a min of 0.08 W at 80 degrees Celsius with an irradiance measurement of 625 W/m2 with the sun at 64.8 degrees from the normal on a cloudy day.

Mechanical Structure

Electronics

Flight Software

Ground Software

Thermistors

Thermal Test Results We immersed our payload in the dry ice chamber from 4:30 to 6:30 pm. We determined that the test was successful because all of the electronics and software were functioning when the box was removed from the chamber. However, the delay time between the relays switching increased during approximately the last 15 minutes of the test. This should not be a problem during flight since the payload will only experience temperatures around -60 degrees C for 30 minutes instead of 2 hours. The temperature inside the payload after the test was 10 degrees C. We also placed a pv cell rubber cemented to a piece of foam in the dry ice (-60 degrees C) as well as in a furnace (80 degrees C). The rubber cement held and the solar cell did not warp.

Pressure Test Results Since the payload cannot fit in the vacuum bell jar, we only placed our electronics in it. We performed the test from 7:00 to 7:30 and we encountered no problems with the electronics or software.

Shock Test Results After the pressure test, we dropped the box from about 10 feet. We did not include the pivot or solar cell because we expect these to break on impact. The payload landed on mulch while collecting nonexistent data and functioned properly afterwards. All components within the payload remained in place on impact.