The EU-funded REGACE Project and the University of Thessaly (UTH) completed installation of Trisolar photovoltaic (PV) systems with CO₂ enrichment in a UTH greenhouse located near Velestino, Greece, with the project’s various components falling into place.
CO₂ enrichment began following completion of the inverters in mid-October. CO₂ is stored in a set of 12 containers with a total capacity of 450 kg, to be used for the enrichment of the plants’ environment within the greenhouse, increasing photosynthesis.
Once CO₂ concentration levels within the greenhouse’s relevant compartments reach the target needed (850 ppm), the greenhouse’s vents automatically close. The greenhouse’s internal climate is monitored using a Sercom NL greenhouse climate control system.
As part of the project’s research component, plants undergo different treatments in the greenhouse’s different compartments, numbered GH2, GH3, GH4 and GH5. Plants in both GH2 and GH5 receive CO₂ enrichment, while those in GH3 and GH4 do not. Plants in GH4 and GH5 are placed under the Trisolar PVs, while those in GH2 and GH3 are not.
This will allow researchers to understand how both the CO₂ enrichment and presence of the Trisolar PVs influence the plants. A new soilless cucumber crop was transplanted to the greenhouse already in mid-September.
“We are confident that we will be able to demonstrate that agrivoltaics can be a major contributor to the EU clean energy portfolio, simultaneously addressing green energy and food security needs,” commented REGACE coordinator Dr. Ibrahim Yehia of the Alzahrawy Society.
The greenhouse is designed to house hydroponic agriculture, and also contains tomato crops. Each compartment within it measures 9.6m wide, 20m long and 5m high, and has hollow PC walls, an arched roof and upper polyethylene cover. Within each compartment, REGACE installed 96 PV panels capable of producing 8 kilowatts.
Climatic data are measured both outside and inside the greenhouse compartments, including air temperature, water vapour pressure, global radiation, CO₂ levels, and PV-cell temperatures. This monitoring is done through the greenhouse’s own climate computer, the PV control computer, and wireless sensors connected to the UTH network.
All measurements are collected by a data logging system and shown real-time online in the project’s web-based database. Measurements of the spectral transmittance of the cover material (including the PVs) are carried out regularly.
The installation in Greece joins earlier completed installations in greenhouses in Germany, Italy and Israel, and is part of REGACE’s goal of demonstrating its solution in six operational research and farming environments with different greenhouse types and crops.
The REGACE system, based on an initial prototype developed by partner TriSolar, intends to provide affordable clean energy combining optimum crop conditions with significant energy generation. The use of CO2 enrichment will expand agrivoltaics usage to areas with low sunshine and low light conditions, as well as warmer Mediterranean locations such as the latest installation in Thessaly.
The UTH team working on the REGACE project in Greece comprises two professors, two senior researchers, two researchers, two PhD students and two BSc students.
