2016 Scientific Ballooning Technologies Workshop Title Efficient Solar Array Power System Author P. Bernasconi, B. Carkhuff (JHU/Applied Physics Laboratory) Abstract We present our custom designed maximum peak power tracker (MPPT) that we will first sue on the Stratospheric TeraHertz Observatory 2 (STO2) balloon gondola to maximize the solar power generation. A MPPT is a microprocessor controlled DC/DC step down converter used by a solar power system to charge a battery. It steps the higher solar panel voltage down to the charging voltage of the battery. The microprocessor tries to maximize the watts input from the solar panel by controlling the step down ratio to keep the solar panel operating at its Maximum Power Point. MPPTs are commonly used on balloon power systems. There are several commercially available units. However, those MPPTs have limitations on how much current they can handle and usually are heavy and produce a fair amount of heat that needs to be dissipated properly to avoid overheating of the unit. Furthermore, those units are designed to operate on the ground and some amount of retrofitting for stratospheric balloon missions is usually required. We have developed a small form factor MPPT that can be attached to a single solar panel module and is designed to operate at float altitude and at temperatures from -80C to +135C. This small MPPT module is light weight and can be produced in quantity so that each individual solar panel module, part of a larger solar array system, will have its dedicated MPPT circuit. Avery MPPT will also provide solar panel module voltage, current, and temperature, thus allowing independent monitoring of the performance of each individual solar panel module. This distributed approach also reduces the risk complete power generation loss in the case of failure of a single large common MPPT. For STO2 we have built 3 MPPT modules and attached them to 3 test solar panel modules that will be flown on STO2 in December 2016.

2016balloontech.umn.edu