Simulation of Radiation and Crop Activity in a Greenhouse Covered with Semitransparent Organic Photovoltaics

Abstract

A solution to the problem of reduction of available photosynthetically active radiation (PAR) due to the cover with conventional opaque photovoltaics (PV) of greenhouses is the use of semitransparent PV. The question is how dense the semitransparent PV should be and how dense the coverage should be in order not to burden plant growth. The present paper assesses the effect of the use of semitransparent organic photovoltaics (OPV) on the greenhouse roof cover on the available PAR inside the greenhouse. The method used is to simulate the transmission of radiation through the cover and into the greenhouse with computational fluid dynamics (CFD) using the discrete ordinates (DO) model. Three combinations of OPV/cover that give a normal (perpendicular) transmittance to PAR of 30%, 45%, and 60%, defining the required PV covering, were examined. Then the radiation transmission during eight indicative solar days was simulated. The results are given in terms of available PAR radiation inside the greenhouse and of crop photosynthesis rate, comparing them with the results of a polyethylene cover without OPVs and external conditions. The reduction observed to the mean daily PAR radiation integral for the cases with normal PAR transmittance of 30%, 45%, and 60% in relation to the bare polyethylene (PE) was 77%, 66%, and 52%, respectively while the respective simulated reduction to the daily average photosynthesis rate was 33%, 21%, and 12%, respectively. Finally, the yearly power production from the OPV per greenhouse length meter for the cases with normal PAR transmittance of 30%, 45%, and 60% was 323, 242, and 158 kWh m−1 y−1, respectively. The results of this work could be further used for the optimization of greenhouse design for maximizing the PAR at the crop level.

Research on the Microclimate of Protected Agriculture Structures Using Numerical Simulation Tools: A Technical and Bibliometric Analysis as a Contribution to the Sustainability of Under-Cover Cropping in Tropical and Subtropical Countries

“…In this regard, it should be mentioned that for daytime climate conditions in low latitude and warm climate regions, it is necessary to limit the incident radiation on the interior of the structures to reduce the generated thermal gradient. This can be achieved through the use of shading screens [134] or from the use of photovoltaic panels that also allow the generation of energy that can be used for other air conditioning tasks [5,206,207].…”

Yield Response and Physiological Adaptation of Green Bean to Photovoltaic Greenhouses

“…However, the common shading applied using shading nets or during intercropping is considerably different from the shading of a PVG, which is higher and persistent, since opaque PV panels shade the direct radiation completely. For this reason, semi-transparent and organic PV technologies are recommended for PVG applications to reduce the impact on the available irradiation and add photo-selective properties that can enhance the crop growth ( Li et al, 2018 ; Baxevanou et al, 2020 ; Friman-Peretz et al, 2020 ).…”

Machine Learning-Based Crop Stress Detection in Greenhouses

“…To further validate the accuracy of the P s_mesR , the recorded values were correlated with P s calculated (P s_cal ) according to the following relationship: P = (αI + Pmax − sqrt((αI + Pmax) 2 − 4θαIPmax))/2θ, where P is the calculated photosynthesis (P s cal ); α is light-limited quantum efficiency (~0.5 µmol (CO 2 ) µmol −1 (photons)); I is the incident PAR radiation in µmol (photons) m −2 s −1 (in the PAR spectrum 1 W m −2 ~ 2 µmol m −2 s −1 ); Pmax is the maximum photosynthesis rate (here considered equal to 30 µmol CO 2 m −2 s −1 ), and θ is the convexity (here considered equal to 0.7, dimensionless) [ 18 ]. This model is known as nonrectangular hyperbola model, and is used to fit the light-response curves and to estimate photosynthetic parameters.…”