Sandbox Solar, a solar developer and recipient of a US federal grant, has released a beta version of its software modeling tool for agricultural power plants. It supports the design and optimization of solar panels and the crops below them.
Agrivoltaics, combining food production and solar energy, is an emerging technology that makes better use of limited land and soil resources. Because the industry is young, there isn’t yet a nifty web-based app like Aurora or Helioscope to help solar developers quickly design plans and factor in the crops below.
Sandbox Solar, a solar contractor, has developed such a tool called Spade. Spade’s goal is to help solar developers determine the best crop types and solar panel layouts for their projects. The tool made it to the fifth and final round of the Department of Energy’s “American Made” solar innovation program. An early beta version of Spade is now available and has already been used to develop solar power projects with potatoes, hemp, hops and other crops.
The software produces several key numerical outputs: irradiance, as well as photosynthetically active radiation (PAR) and mean photosynthetic photon flux density (PPFD), two types of light measurements less familiar to the solar industry.
PAR refers to wavelengths useful for photosynthesis, while PPFD measures the density of photons in this range that reach a given surface area. Not all wavelengths of light are equally effective for photosynthesis; plants generally use blue (400 nm to 500 nm) and red (600 nm to 700 nm) light more efficiently than green (500 nm to 600 nm) light. PAR and PPFD are both important in understanding and optimizing light conditions for plant growth and photosynthesis.
The data is displayed both visually in graphs and numerically in watts per square meter and PAR/PPFD values. Again, PAR is the amount of useful light that reaches the plants growing among the solar panels. Most crops compatible with agriculture actually benefit from the reduced radiation provided by solar panel shading.
Spade’s team told us that a fundamental approach to optimizing agri-electricity projects involves the three Cs: configuration, climate and crops. By carefully considering these factors, a developer can refine their strategies for placing and raising solar panels to maximize land use, ensuring the best possible balance between energy production and agriculture.
The graphic below depicts Spade designer Tom Hickey’s changing inputs to solar designs, which then produce different potential solar design outcomes that meet the project’s requirements. Hickey has worked at Sandbox for over five years and currently works part-time with the National Renewable Energy Laboratory. He uses Spade directly in customer design work and in Sandbox’s agricultural projects.
“Spade has revolutionized what I’ve been able to do in-house,” said Hickey.
In a recent conversation with pv-lehti USA, Alexis Pascaris—director of Spade software development—noted the unique incentives of Massachusetts’ agrovoltaic program and the state’s SMART solar program. While Hickey and Pascaris lead the processes, Spade has partnered with developers as a subcontracting professional who liaises with the Department of Agriculture to move projects through the SMART application process. Pascaris suggested that Spade’s tone analysis tools are more accurate than those currently mandated by Massachusetts.
Sandbox Solar founder Ian Skor said he believes the current iteration of the tool is robust enough to meet the immediate needs of both the company and its consulting clients. However, he admits that there is room for growth in the development of the software’s user interface to improve online interaction and improve its overall functionality.
Alexis said the company is developing a budget to take Spade to the next level so that they can begin a request for investment proposals sometime in 2023. Currently, the team does not have any fully installed projects developed with Spade. However, construction is slated to begin soon on several Spade-designed projects, including an in-house vertical bifacial project.
