POSCAS is a modular, open-source cold-frame system designed to integrate semi-transparent photovoltaic (PV) modules for agrivoltaic research and small-scale food production. It enables testing of various PV transparency levels and spectral properties to optimize crop growth and energy generation. The design is parametric, allowing customization of dimensions, tilt angles, and insulation via OpenSCAD scripts. Components can be fabricated using distributed recycling and additive manufacturing (DRAM) techniques, utilizing recycled plastics. POSCAS serves as both a passive cold frame and a platform for automated greenhouse systems.