Photovoltaic greenhouses are mixed systems, combining electricity and agricultural production in the same area. Moreover, this type of greenhouse conserves all the properties of a conventional greenhouse, as well as offering the possibility of producing and selling electricity. The aim of the present study is to assess both the impact of the shade caused by the photovoltaic panels on the microclimate and the quality of fruits in the greenhouse. Measurements were carried out in an experimental Canary type greenhouse covered with flexible photovoltaic panels on 10% of its total roof area. Results illustrate that this occupancy rate of the photovoltaic panels arranged in checkerboard pattern does not have a significant effect on the agronomic parameters e.g. height, stem diameter and tomato yield, and climatic parameters under the greenhouse cover. Additionally, the presence of photovoltaic panels has a negative effect on the development of the population of Tuta absoluta.

Introduction

Greenhouse technology is a major breakthrough in agriculture, because it favors off-season cultivation and also gives greater crop productivity. The greenhouse is used to protect crops from severe weather conditions such as rain or wind (Dannehl et al., 2014). The greenhouse microclimate is characterized by a set of climatic parameters, such as temperature (Sethi and Sharma, 2008), relative humidity (Kim et al., 2008), carbon dioxide (CO2) concentration (Körner et al., 2007) and solar radiation (Ioslovich, 2009); which are different from the outside conditions. Each of these parameters is strongly linked to the outside weather conditions as well as the particular characteristics of the greenhouse. The greenhouse like all agricultural structures consumes energy either in a direct way i.e. irrigation, artificial lighting, heating, air cooling, aeration (Vox et al., 2010; Hardin et al., 2008), or in an indirect way i.e. nitrogen fixation technology and acquisition of fertilizers ‘transport’ (Allardyce et al., 2017; Sonneveld et al.,2010; Stanghellini, 1987; Bot et al., 2005). Currently most of this energy is fossil (Campiotti et al., 2010; Vourdoubas, 2015) e.g. oil, coal, natural gas. Although diversified and very abundant, these resources are becoming harmful on human the health and the environment. Their use generates considerable carbon dioxide, partly responsible for global warming. This effect threatens many populations around the world, endangering the geopolitical stability in certain regions of the globe due to major climatic phenomena. To address these concerns, more and more countries are putting into place incentives not only to save energy but also to produce energy by other means, often referred to as “clean” in reference to the fact that it does not generate carbon dioxide. These means of production are mainly derived from renewable energies, that is to say, whose resources are sustainable. These include “solar” energy. The latter term actually covers many technologies, including photovoltaic energy. This system transforms sunlight directly creating electricity immediately. Photovoltaic energy is renewable, natural (Wand and Leuthold, 2011), readily available, sustainable, clean and cheaper than fossil energy (Ftenakis and Kim, 2009). This energy is becoming increasingly used. Moreover, this energy is the most used and the most widespread in the world. Therefore, the use of photovoltaic energy in greenhouses is a major objective for sustainable greenhouse crop production (Kadowaki et al., 2012).