Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain

Kujawa, Anna; Hanrieder, Natalie; Rodríguez, Sergio González; Hristov, Lyubomir; Blanco, Manuel Jesus; Álvarez, Leontina Berzosa; Gallardo, Ana Martínez; González, Adoración Amate; Fernandez, Marina Casas; Luque, Francisco Javier Palmero; Godoy, Manuel López; Alonso-García, María del Carmen; Carballo, José Antonio; Tirado, Luis Fernando Zarzalejo; Cornaro, Cristina; Pitz-Paal, Robert

doi:10.3390/agriengineering8060245

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Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain

by

Anna Kujawa

^1,*

,

Natalie Hanrieder

¹,

Sergio González Rodríguez

¹,

Lyubomir Hristov

¹,

Manuel Jesus Blanco

²

,

Leontina Berzosa Álvarez

³,

Ana Martínez Gallardo

³,

Adoración Amate González

³,

Marina Casas Fernandez

³,

Francisco Javier Palmero Luque

⁴,

Manuel López Godoy

⁴,

María del Carmen Alonso-García

⁵

,

José Antonio Carballo

²

,

Luis Fernando Zarzalejo Tirado

⁶

,

Cristina Cornaro

⁷

and

Robert Pitz-Paal

^8,9

¹

Institute of Solar Research, German Aerospace Center (DLR e.V.), Calle Dr Carracido 44, 04005 Almeria, Spain

²

Plataforma Solar de Almería, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Ctra. de Senés s/n, 04200 Tabernas, Spain

³

Anecoop S. Coop., Calle Monforte 1, 46010 Valencia, Spain

⁴

Fundación Finca Experimental UAL-Anecoop, Paraje Los Goterones s/n, 04131 Almeria, Spain

⁵

Photovoltaic Solar Energy Unit, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Avda. Complutense 40, 28040 Madrid, Spain

⁶

Renewable Energy Division, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Avda. Complutense 40, 28040 Madrid, Spain

⁷

Department of Enterprise Engineering, University of Rome Tor Vergata, 00133 Rome, Italy

⁸

Institute of Solar Research, German Aerospace Center (DLR e.V.), Linder Hoehe, 51147 Cologne, Germany

⁹

Faculty of Mechanical Engineering, RWTH Aachen University, 52062 Aachen, Germany

^*

Author to whom correspondence should be addressed.

AgriEngineering 2026, 8(6), 245; https://doi.org/10.3390/agriengineering8060245 (registering DOI)

Submission received: 4 May 2026 / Revised: 28 May 2026 / Accepted: 12 June 2026 / Published: 14 June 2026

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Abstract

Watermelons account for 7% of the world’s fruit vegetable production. In the European market, Spain contributes around 35% of total watermelon supply, with the majority grown in greenhouses in Almería, Southern Spain. This study presents experimental results from the first agrivoltaic watermelon trial conducted in a raspa-y-amagado greenhouse during the 2024 growing season in Almería, Spain. Watermelons were cultivated under two shading treatments with 30% and 50% of the roof area covered with PV modules and compared against an unshaded control group. Throughout the experiment, temperature values in the 30% and 50% zones were

2.2

^{\circ} C

and

4.3

^{\circ} C

lower than in the control zone, respectively. The unshaded control zone and the 30% shading treatment maintained DLI conditions within the optimal range between 21/

m

/day and 32/

m

/day for most of the crop cycle, while the 50% shading zone remained largely above the minimum threshold of 15/

m

/day required for adequate crop growth. No statistically significant differences were observed in fruit weight, rind width, fruit firmness, or soluble solids content at harvest. In addition, the experimentally measured irradiance data from this study were compared with simulations from a previously established irradiance model. The model was applied to the raspa-y-amagado greenhouse, and the experimental data were used to perform a long-term comparison between simulated and measured irradiance for 265 days of data. The irradiance model accurately reproduced shading effects from both the PV modules and greenhouse structure, achieving nRMSE values of 0.09, 0.18, and 0.27 for the control, 30% shading, and 50% shading zones, respectively.

Keywords: agrivoltaic; photovoltaic greenhouse; watermelon; shading; microclimate; yield; fruit quality

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MDPI and ACS Style

Kujawa, A.; Hanrieder, N.; Rodríguez, S.G.; Hristov, L.; Blanco, M.J.; Álvarez, L.B.; Gallardo, A.M.; González, A.A.; Fernandez, M.C.; Luque, F.J.P.; et al. Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain. AgriEngineering 2026, 8, 245. https://doi.org/10.3390/agriengineering8060245

AMA Style

Kujawa A, Hanrieder N, Rodríguez SG, Hristov L, Blanco MJ, Álvarez LB, Gallardo AM, González AA, Fernandez MC, Luque FJP, et al. Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain. AgriEngineering. 2026; 8(6):245. https://doi.org/10.3390/agriengineering8060245

Chicago/Turabian Style

Kujawa, Anna, Natalie Hanrieder, Sergio González Rodríguez, Lyubomir Hristov, Manuel Jesus Blanco, Leontina Berzosa Álvarez, Ana Martínez Gallardo, Adoración Amate González, Marina Casas Fernandez, Francisco Javier Palmero Luque, and et al. 2026. "Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain" AgriEngineering 8, no. 6: 245. https://doi.org/10.3390/agriengineering8060245

APA Style

Kujawa, A., Hanrieder, N., Rodríguez, S. G., Hristov, L., Blanco, M. J., Álvarez, L. B., Gallardo, A. M., González, A. A., Fernandez, M. C., Luque, F. J. P., Godoy, M. L., Alonso-García, M. d. C., Carballo, J. A., Tirado, L. F. Z., Cornaro, C., & Pitz-Paal, R. (2026). Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain. AgriEngineering, 8(6), 245. https://doi.org/10.3390/agriengineering8060245

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Experimental Assessment and Modeling of Solar Irradiance for an Agrivoltaic Greenhouse for Watermelon Production in Southern Spain

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