Parametric Open-Source Cold-Frame Agrivoltaic Systems (POSCAS)

An open-source cold-frame agrivoltaic system or a greenhouse with photovoltaic modules.


Parametric via OpenSCAD scriptFor the frame, the thickness of the walls, type of wall insulation, possessing a floor or being directly located on the ground, & the tilt angle of the module
3D printed partsMethod: DRAM
Material: any waste plastics/thermopolymers
Material: any waste plastics/thermopolymersCable zip ties
Material: nylon (Type 21 UL)
Features: Heavy-duty, marine grade, UV resistant,
Size: 8.5 mm wide, 355 mm long
Tensile strength rating: 54 kg
Withstand temperatures from -40 to 85 C
PV modulesthin-film based semi-transparent PV
crystalline-silicon spherical solar microcells


This tech spec was submitted by Joshua Pearce as part of the University Technology Exposure Program.

Problem / Solution

Since PV systems are considered significant net energy producers, their growth is essential for the environment. The continuous development helps them to pay for their energy in a year, but it also has drawbacks. Cities with a high population density do not have enough solar array space to cover their power needs, especially when heating and transportation are not included. Land use conflicts occur because PV demands large surface areas, frequently found in rural areas where agriculture is produced. Fortunately, agrivoltaics may co-develop land for both PV electrical generating and agriculture, satisfying escalating energy and food demands without causing conflict. However, agrivoltaic optimization has barely started.

The study developed a brand-new testing method known as the parametric open-source cold-frame agrivoltaic system (POSCAS). It is employed as a tiny greenhouse for agricultural protection in cold weather. Additionally, it is designed to test transparent solar photovoltaic (PV) modules with an emphasis on the agrivoltaic sector. The integrated PV module roof also powers the controls and may be connected to a microinverter to generate electricity. Additionally, it can be used in an experimental array to test food and energy production. Any sort of PV module with partial transparency can use the invention. Additionally, a variety of POSCAS systems allow for the testing of agrivoltaic effects from the percentage of transparency of the modules by varying the density of silicon-based cells or the thickness of a thin film PV material, as well as different types of optical enhancement, anti-reflection coatings, and solar light spectral shifting materials in the back sheet. Additionally, every agrivoltaic characteristic can be altered to find the best PV designs for a particular agricultural crop.


Parametric Frame Design

PV modules already come in at least hundreds of different types, and it is anticipated that they will expand in size and materials as time goes on. The design was put up parametrically to allow adaptation of any size of PV module and utilize distributed manufacturing, ensuring that POSCAS systems are known to be universally usable and future-proof. A parametric OpenSCAD script stored at the Open Science Framework determines the frame's thickness of the walls, kind of wall insulation, position, and tilt angle of the module in the design. The solid modeling application used in the design, OpenSCad version 2019.05, is regarded as a free and open-source script. The utilized script generates a 3-D printed file (STL) that enables the frame body to be produced utilizing distributed recycling and additive manufacturing DRAM methods using scrap plastics.


Using DRAM to Fabricate a POSCAS

Open source waste plastic extruders (recyclebots) convert post-consumer plastic waste into 3-D printing filament that may be used in traditional fused filament 3-D printers for the construction of POSCAS. The recycle bots are now mounted on 3-D printers for direct printing with fused filament fabrication. After democratizing additive manufacturing, the open source 3-D printing community has adopted open source techniques for recycling 3-D printing waste. The number of DRAM for thermo polymers demos is currently very high. Since most labs have easy access to various thermoplastics, these examples offer material versatility for producing components of the POSCAS.

Additionally, CURA v 4.11.0, a well-known open source slicing application for various infill parameters, is used in this study to calculate the mass of the plastic frame. The cost of ASA is sensitively computed using the following prices: (1) commercial filament from Amazon costs $30/kg; (2) commercial pellets cost $8/kg; (3) recycled commercial pellets cost $2.50/kg; and (4) DRAM costs $0.025/kg. Since ASA is resistant to weather and UV rays, it is used as an example polymer. Zip ties are used as fasteners in the design's heavy-duty marine-grade nylon cable to provide a cheap and straightforward system. The structural frame of the POSCAS is connected to the module frame using cable zip ties.

Additionally, POSCAS has 355 mm long PV aluminum frames with a tensile strength rating of 54 kg that cost $0.09 each and 8.5 mm UV-resistant black zip ties. The zip ties are constructed with type 21 UL industrial strength nylon 6/6 that is UV resistant and resistant to temperatures ranging from 40 to 85 C. Additionally, the manufacturer of the module affects how many fasteners are used.


Agrivoltaic Module Experimental Design with a POSCAS

Even if PV modules are regularly used in agrivoltaics, the POSCAS was created to investigate the effectiveness of PV modules specifically designed for semi-transparent agrivoltaic applications. Semi-transparent PV utilized for integrated PV (BIPV) construction can be either thin-film based, where the thickness of the active layer is changed to affect the module's transparency, or crystal silicon technology, where the cell spacing is changed to control the transparency. Solar microcells made of crystalline-silicon must be used for the later technique. The matrix can also be produced for thin films by increasing the RGB color. Additionally, a white-black OpenSCAD script is utilized to arrange the cells following the input specifications.


A research paper describing the challenge, design, and outcome of the research.

Joshua M. Pearce

Wevolver 2023