Sebastian Zainali

Agrivoltaic (AV) systems offer a promising solution to mitigate land-use competition between agricultural production and renewable energy conversion. However, photovoltaic (PV) modules and related supporting structures modify the local microclimate, influencing evapotranspiration (ET) processes. Despite recent advances in computational fluid dynamics (CFD) applications for AV systems, ET remains a complex microclimatic parameter that has received limited validation. This study develops a hybrid framework coupling a three-dimensional CFD model and field measurements with the Penman-Monteith FAO 56 approach to estimate the spatial distribution of reference evapotranspiration (ETo) in AV systems. The CFD model solves RANS equations, k-ε standard turbulence model, discrete ordinate radiation model, and it applies solar heat flux using solar load model with ray tracing approach. The proposed method is validated using field measurements from a vertically-mounted AV (VMAV) experimental facility at Kärrbo Prästgård, Sweden. The ETo is measured using an in-house developed weighing micro-lysimeter for three consecutive clear sky days. The validated model is then applied to investigate edge effects and compare ETo distributions among VMAV, ground-mounted AV (GMAV), and overhead AV (OAV) configurations. The results demonstrate that the hybrid framework accurately captures ETo variations that are otherwise overlooked by standard weather station data. By providing high-resolution spatiotemporal mapping, this approach serves as a decision-support tool for precision irrigation and the strategic optimization of monitoring networks to capture microclimatic heterogeneity. At the daily scale, comparative simulations show that, relative to the control area, GMAV, OAV, and VMAV configurations reduce ETo by 22%, 12.8%, and 13.1%, respectively.

Saffron is a bulbous herb with edible flowers and is considered a high-value crop. However, cultivating saffron at northern latitudes presents challenges, primarily due to adverse weather conditions during its productive phase. Therefore, this study tested whether microclimate modifications caused by a single-axis tracking agrivoltaic (AV) system could enhance saffron production. The experiment was carried out near Västerås, in central Sweden. A field trial was set up to cultivate saffron both under open-field conditions and beneath the photovoltaic (PV) modules of a single-axis tracking system, utilizing the area that is typically unused for cultivation. Beneath the AV system, the maximum density of 24.3 flowers/m2 was observed, compared with a maximum of 0.5 flowers/m2 in the open field. In total, 226 flowers were counted beneath the AV system, yielding 1.09 g dry stigma, whereas only three flowers were observed in the open field, corresponding to 0.02 g dry stigma. Results from this small-scale experiment correspond to a potential yield of up to 203.4 g/ha of dry stigma under a single-axis tracking AV system, compared with 90.1 g/ha in open-field conditions. In addition, intercropping saffron within AV systems improved land-use efficiency by reducing land loss due to PV panel structures from 10% to 3%. As a high-value, low-input crop, saffron cultivation under AV systems therefore offers potential economic benefits for farmers. Overall, these results demonstrate that AV systems can positively influence saffron productivity at northern latitudes. However, further research is required to assess the long-term productivity of saffron under AV systems, as the crop is cultivated for a single year in this study but can be maintained for 5 to 10 years.

Agrivoltaic (AV) systems offer a promising pathway for energy conversion on agricultural land while supporting crop cultivation. However, their widespread adoption is hindered by agronomic uncertainties, including the lack of quantitative and qualitative crop performance data across regions and system configuration. In this context, the present study investigated the growth, yield, and quality of oat cultivated under an AV system. The experiment was conducted near Fellingsbro, in central Sweden, under rainfed conditions. In May 2024, oats were cultivated under a vertical AV system and in a reference area without photovoltaic (PV) modules. Leaf area index (LAI), dry matter yield, thousand kernel weight (TKW), and crude protein and fat content were measured to evaluate morphological, productive, and qualitative parameters. The results show that LAI was significantly lower under the AV system. An 8.4% reduction in total biomass (kernel + straw, in dry matter kg/ha) was observed under the AV system; however, this difference was not statistically significant. TKW, crude protein, and crude fat contents (% of dry weight) under the AV system showed no significant differences compared to the reference. These findings highlight that moderate shading under vertical AV systems (with a seasonally average reduction of 41.8% in photosynthetically active radiation in our case) can sustain stable oat yields both quantitatively and qualitatively. Additionally, relative crop yields varied across the AV system row, where yield in the west, middle, and east part were 110.1%, 85.9%, and 78.8% with PAR reductions of 42.3%, 36.6%, and 46.6%, respectively. It highlights the importance of diurnal shading dynamics. This is likely due to favorable west-side shading, which provides full sun during peak photosynthesis and beneficial afternoon shade in accordance with the peak of vapor pressure deficit.

This study evaluated the economic feasibility of various agrivoltaic (APV) systems in Sweden using Monte Carlo simulations, focusing on two different scenarios: dynamic electricity prices (Wholesale Price Scenario) and fixed electricity prices (Power Purchase Agreement (PPA) Scenario). The assessment of small-scale systems (1-ha) revealed that using average PPA prices (0.058 €/kWh) can lead to unprofitable installations, particularly in the absence of government incentives. In contrast, simulations assessing the wholesale price scenario show that all systems achieve positive net present value (NPV), highlighting the importance of accounting for multi-year price variability. By exploring economies of scale for vertical APV systems, the Capital Expenditure (CAPEX) decreases significantly from 0.06 €/kWh for 1 ha to 0.043 €/kWh for 5 ha, representing a 28% reduction. At a scale of 5 ha for the vertical APV system (equivalent to 1.9 MWp installed capacity), the mean levelized cost of electricity (LCOE) approaches the PPA price of around 0.052 €/kWh. This suggests that even at a fixed contractual price near the PPA, a somewhat larger-scale APV system can yield positive income. The profitability of APV systems improves if self-consumption is considered. The one-axis APV system performs best, with NPVs rising from 63 k€ to 133 k€ and 229 k€ at 0%, 25%, and 50% self-consumption, respectively. The vertical APV system becomes viable at 25% and 50% self-consumption, with NPVs of 15 k€ and 91 k€, respectively. The elevated APV system is the least attractive option for the investigated location and assumptions.

Agrivoltaic (APV) systems, which co-locate photovoltaic (PV) panels with agricultural production, have emerged as a promising strategy to simultaneously address water, energy, and food sustainability challenges. However, the optimal design of such systems remains complex due to competing objectives, site-specific conditions, and increasingly stringent policy constraints. This study presents a multi-objective optimisation framework for APV systems design that integrates climatic variability, crop performance modelling, PV system behaviour, and national policy thresholds with a water-energy-food (WEF) nexus approach. Using a genetic algorithm (GA) as the optimisation technique, the model explores optimal configurations of three APV system types: vertical, one-axis tracking, and overhead fixed-tilt. The optimisation considers four design parameters including module tilt, azimuth orientation, row pitch, and system height. Simulations are carried out at three geographically diverse European locations: Sweden, Germany, and Italy, over a six-year crop rotation period. The framework incorporates constraints from Swedish subsidy requirements, German yield retention standards, and Italian guidelines. A composite WEF index enables flexible prioritisation among objectives and reveals strong trade-offs between energy conversion and crop productivity (correlation ≈ −0.99). The results demonstrate that combining national policies with recommended best practices can render APV deployment practically infeasible at the development stage if no accurate APV integrated models are available to clearly depict the impact of shading on microclimate and crop growth. The row pitch emerged as the most influential design variable, with optimal spacing between 5–10 meters depending on location and constraints. Furthermore, the land equivalent ratio (LER) for crops can vary by up to 10% depending solely on interannual weather variability.