Impact of Additive Manufacturing Materials on Thermal Performance of Silicon Reference Cells.

Additive manufacturing, or 3D printing, is quickly becoming a widespread manufacturing method offering timely and cost-effective build times for unique part geometries with an increasing range of material offerings. One unique use for additive manufacturing is constructing the housing for reference solar cells, which are crucial instruments for evaluating the electrical performance of photovoltaic solar cells and modules. These instruments, which require good thermal conduction, are costly to manufacture because they are usually machined from aluminum using precision milling machines. In this work, we set out to evaluate several presently available additive manufacturing materials for their thermal properties when used to house reference solar cells. We fabricated several types of reference cell instruments with a tabletop, filament-based 3D printer using polylactic acid (PLA) and composite PLA/metal materials with different infill percentages. Furthermore, we fabricated several all-metal 3D printed reference cells using a binder jet printed stainless steel-bronze material blend and compared the thermal properties of all 3D printed instruments against a standard aluminum housing reference cell. Measurements included temperature monitoring of an embedded thermocouple sensor on an isothermal plate under the ambient environment and when exposed to high irradiation under a solar simulator. Current vs voltage measurements were also taken under the solar simulator and the open circuit voltage results were used to verify the actual silicon cell temperature. Our findings indicate that the stainless steel-bronze option can function well as an alternative to traditional aluminum-based housings, while the lower-cost metal-PLA composite can only be used under indoor light spectra or when used in a flash-type solar simulator when the instrument is not exposed to excessive radiation and heat.