- Email: [email protected]
Performance of photovoltaic canarian greenhouse: A comparison study between summer and winter seasons
Solar Energy 198 (2020) 275–282
Contents lists available at ScienceDirect
Solar Energy journal homepage: www.elsevier.com/locate/solener
Performance of photovoltaic canarian greenhouse: A comparison study between summer and winter seasons
T
⁎
K. Ezzaeria, , H. Fatnassib, A. Wifayac, A. Bazgaoua, A. Aharounea, C. Poncetb, A. Bekkaouid, L. Bouirdena a
Thermodynamics and Energetic Laboratory, Faculty of Sciences, Agadir, Morocco Université Côte d'Azur, INRA, CNRS, ISA, France c Regional Centre of Agricultural Research, Agadir, Morocco d Mechanization Agricultural Department, IAV Hassan II, Rabat, Morocco b
A R T I C LE I N FO
A B S T R A C T
Keywords: Flexible photovoltaic panels South Mediterranean area Tomatoes Microclimate Shading Renewable energy
A large-scale use of the renewable energy in agriculture has become an optimal way to successfully deal with the issues of sustainability and climate change. Recently, the integration of solar panels on the roof of the greenhouse gave birth to a new crop production system called photovoltaic greenhouse. In this paper, we investigated the shading effect of the flexible photovoltaic panels, mounted on the greenhouse roof area in the checkerboard format, on the microclimate and the tomatoes yield during the summer and winter period. This study was undertaken in a two tomato canarian greenhouses, typical of the south Mediterranean region. The results of our study showed that the photovoltaic panels covering 40% roof area of the canary type greenhouse does not have a significant effect on the climatic parameters. Additionally, during the hot period, the photovoltaic panels reduced the temperature inside the greenhouse and sometimes falling in the optimum range for the tomatoes growth. Furthermore, this occupancy rate of the photovoltaic panels does not have a significant effect on the overall yield of tomatoes.
1. Introduction In recent decades, the cultivation of horticultural plants in greenhouses, knew a growing throughout the world. The reason for this development is due to population growth and the increased demand for fresh produce throughout the year. Nevertheless, this agro-system is threatened by several recent evolutions that weaken it. One of the major problems facing by the producers, is the significant increase of the price in energy. For that, the farmers who want to remain competitive must invest at the same time in the greenhouse agricultural production and other production e.g. the photovoltaic electrical production. The photovoltaic energy is an attractive renewable energy among electrical power resources (Ezzaeri et al., 2019a), because it is abundant, free (Tripathy et al., 2017), and have less environmental impact (Selvi and Baskaran, 2015; El-khatib et al., 2017). However, with the generous government subsidies allocated to conversion to clean energy in agriculture, agricultural lands experienced the invasion of the photovoltaic installations in recent years (IPCC, 2011; U.S. Energy Information Administration, 2016). To resolve
⁎
this energy-food conflict, it is more judicious to combine these two production systems under the same area (Ezzaeri et al., 2018; Wang et al., 2016; Xue, 2017; Esen et al., 2013). The fundamental challenge of this technology is to maintain a higher quality of agricultural produce and a lower impact on the environment (Poncet et al., 2012). The challenge is, therefore, to arrive to a real photons sharing between electrical production and crops to allow profitable agricultural activity (Ezzaeri et al., 2019b). The spectrum sunlight ranging from 400 nm to 700 nm is exactly what plants needs for the photosynthesis process, and wavelengths more than 700 nm could be useful for other than photosynthesis (Sonneveld et al., 2010; Yano et al., 2007). Several research studies have been conducted on the greenhouses equipped by flexible and semi-transparent photovoltaic panels (Marucci et al., 2012; Yano et al., 2014; Yang et al., 2015; Buttaro et al., 2016; Cossu et al., 2016; Minuto et al., 2009; Sugiura et al., 2002; UrenaSanchez et al., 2012; Yano et al., 2007; Kadowaki et al., 2012; Saifultah et al., 2016). Trypanagnostopoulos et al. (2017) studied the performance results of energy production and lettuce plant growing inside the greenhouse
Corresponding author.
https://doi.org/10.1016/j.solener.2020.01.057 Received 12 September 2019; Received in revised form 17 January 2020; Accepted 21 January 2020 0038-092X/ © 2020 Published by Elsevier Ltd on behalf of International Solar Energy Society.
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Fig. 1. Photos of the photovoltaic and the control greenhouses.
system under two seasons winter and summer i.e. when the intensity of solar radiation is at these two extremes (weak and strong). (iii) Also new, installing the PV panels on 40% of the roof surface of the greenhouse represents special challenge since there is a risk of affecting the crop production under this kind of greenhouse. Therefore, the paper results can be useful for farmers in south Mediterranean region to measure the maturity level of this innovative agro-system and to see if they can achieve a balance between crop and photovoltaic electricity production.
when 20% of their roof area was occupied by the photovoltaic panels’ pc-Si type. The results showed that the photovoltaic panels produced 50.83 kWh m−2 for the characteristic cultivation period of Feb-MarApr, and the lettuce plants growing results under the shading effect were satisfactory. Marucci et al. (2017) analysed the variation of shading under a tunnel greenhouse provoked by the flexible and transparent photovoltaic panels in a checkerboard arrangement. The results show some regularity in the shading percentage, mainly due to the format greenhouse, the shading in the middle of the day is almost always under the tunnel greenhouse, from mid-March to mid-September, and partly outside partly inside the greenhouse in the other months of the year. Castellano et al. (2016) investigated experimentally and numerically the variation over space and time of the amount photosynthetic photons flux density inside a mono-span greenhouse their roof entirely covered by the polycrystalline photovoltaic panels, the analysis showed a good capability of the numerical model to predict the shading effect under a photovoltaic greenhouse. Al-Shamiry et al. (2007) studied photovoltaic hybrid system for cooling a tropical greenhouse, this system includes 48 photovoltaic solar Panels with 18.75 W each, one inverter, 1 charge controller and a battery bank (including 12 batteries). The PV system is located at University Putra Malaysia (UPM) Research Park. The national electricity grid was used as a backup unit. The load consisted of two misting fans for cooling greenhouse (during test period time) with 400 W electric power and five hours (11:00 am to 16:00 pm) daily operation. The results showed that the photovoltaic system would be suitable to supply electricity to cover the loads requirement demands without using energy from the grid. Sonneveld et al. (2010) proposed a new type of greenhouse, which combines reflection of near infrared radiation with electrical power generation using hybrid photovoltaic cell/thermal collector modules. The experimental results with the electricity-producing greenhouse prototype prove that part of the near infrared radiation can be converted into useful electrical and thermal energy. The reflected near infrared radiation can be focused with a circular trough reflector integrated in the greenhouse cover resulting in a geometrical concentration factor of 30. An electrical peak power of approximately 30 Wm−2 and a thermal peak power of 121 Wm−2 are expected with an illumination of 900 Wm−2. Previous photovoltaic greenhouse studies have commonly used conventional flat or planar flexible photovoltaic panels (Urena-Sanchez et al., 2012; Yano et al., 2010; Sugiura et al., 2002; Sonneveld et al., 2008; Alonso et al., 2012; Yano et al., 2007; Kadowaki et al., 2012; Al-Ibrahim et al., 2006; Yano et al., 2005). In this context, this work aims to assess the shading effect of the flexible photovoltaic panels, mounted on 40% of the canarian greenhouse roof area, on the microclimate and the crop yield during summer and winter periods. The novelty of this study is threefold: (i) It presents a first application of the PV panels on the canarian greenhouses i.e. greenhouses widespread in the south Mediterranean region. (ii) It evaluates this
2. Materials and methods 2.1. Site The measurement campaigns were performed from January to June 2018 in the Regional Center for Agricultural Research INRA in southern Agadir (Latitude: 30° 13′ N, Longitude: 9° 23′ W, Altitude: 80 m) on the Atlantic coast of Morocco where the weather is moderate. During winter season, the weather in this region is not so cold, the minimal daytime winter temperatures is around 11 °C. 2.2. Greenhouse description The measurements were carried out in two identical North- South oriented canarian greenhouses, were located along their common North-South axis with 7 m separation. Each greenhouse occupies a surface area of 172 m2, with the dimensions, 11.0 m wide, 15.6 m long, 4.0 m gutter height, 5.0 m in the ridge and a roof slope of 10°. The greenhouses cover material was a plastic polyethylene film with 200 µm of thickness and 75% of light transmission. The ventilation was provided by manually opened side equipped with insect-proof nets. One of the two greenhouses was covered by opaque photovoltaic panels and the second without. As shown in Fig. 1, 132 opaque photovoltaic panels were fixed on the roof of the greenhouse at tilted angle of 10°, placed in checkerboard format to promote the solar radiation transmission (Fatnassi et al., 2015). Each photovoltaic module has the following dimensions: 1000 mm × 500 mm × 3 mm (Table 2). The photovoltaic panels were located at 3 cm over the plastic cover to allow air to circulate circulation between the panels and the plastic cover. 2.3. Crop Tomato (Solanum lycopersicum, cultivar: Pristyla, Rijk Zwaan Company) were planted on October, 11th 2017 in pots, with a density 0.7 plants/m2, there were 40 pots divided in four rows, each row contains 10 pots, each pot had three plants. The distance between rows was 120 cm and between plants was 30 cm. All tomato plants get the same drip irrigation quantity. The agronomic parameters measurements were plants height, leaf area, steam diameter and number of leaves inside the photovoltaic and control greenhouses. Six tomato plants were picked in each row. The planting rows inside the two greenhouses are 276
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Fig. 2. Location of the photovoltaic greenhouse in the experimental field, and the positioning of each pyranometer in this greenhouse.
Fig. 3. Section of the experimental greenhouse and the location of the experimental sensors used in the present experience.
oriented North-South, perpendicular to the wind direction.
Table 1 Specification of the instruments. Instrument name
Measurement range
Accuracy
2.4. Microclimate monitoring
Pyranometer Kipp&zonen CMP11 Pyranometer SP1110 Vaisala HMP60
0–2000 W/m2 0–3000 W/m2 T: −40 °C to +60 °C RH: 0–100%
± 5% ± 5% ± 0.6 °C ± 5%
Microclimate variables such as temperature, relative humidity, solar radiation, were measured on the two greenhouses i.e. photovoltaic and control, throughout a crop cycle from January 3, to September 24, 2018. In addition, meteorological data were measured by an external weather station. The solar radiation was measured in nine locations in the 277
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
3. Observations and results
Table 2 Characteristics of the photovoltaic panels. Name
MX-FLEX Protect
Peak power (Pmax) Open Circuit Voltage (Voc) Short circuit Current (Icc) Voltage (Vmp) Current (Imp) dimensions Weight Module efficiency
100Wc 23.4 V 5.4 A 19.8 V 5.05 A 1000 × 500 × 3 mm 1.7 kg 19%
Fig. 4 shows the variation of global solar radiation inside and outside the two greenhouses during nine months. The analysis of theses graphs shows that the high value of solar radiation was detected during July when the mean of the external global radiation is 949.11 W/m2. These values are respectively 617.37 W/m2 and 305.13 W/m2inside the control and the photovoltaic greenhouse, which presents a reduction of 50.50% of the solar radiation due to the presence of the PV panels, compared to the control greenhouse. This value drops to 41% during the cold period in January. Figs. 5 and 6 show the variation of air temperature during the cold and hot period inside and outside the two greenhouses (photovoltaic and control). Based on these two figures we can see that the temperature inside the two greenhouses follows an almost sinusoidal evolution; the difference of air temperature between the shaded and unshaded greenhouse was higher during summer, the temperature was higher in the unshaded greenhouse by 8% compared to the shaded greenhouse, due to the presence of photovoltaic panels, therefore, during the winter season the air temperature inside the photovoltaic and control greenhouses is almost at the same level, the high values of the temperature inside the photovoltaic greenhouse was 23.93 °C and inside the control greenhouse was 23.51 °C, the maximum difference between the two greenhouses reach a values of 0.75 °C. This small difference of air temperature is due to the photovoltaic panels shading which causes an accumulation of solar radiation inside the greenhouse, which led to a slight rise in air temperature. During the summer period, it appears a difference between the temperatures of the two greenhouses in daytime. The high values were detected in the control greenhouse vary between [46.81 °C, 48.37 °C] compared to the photovoltaic greenhouse [43.78 °C, 44.68 °C] representing a high difference reaches 3.69 °C between the two greenhouses. Figs. 7 and 8 shows the variation of relative humidity inside and outside the two greenhouses during the cold and hot period. The relative humidity in the two greenhouses does not show great variations during the night for the cold or the hot period. Outside temperature is
photovoltaic greenhouse (Fig. 2) and in one location in the control greenhouse using nine pyranometers CMP3 and SP1110 (Campbell Scientific Ltd. UK) positioned at 3 m above the ground level. The CMP3 (Kipp&Zonen, Campbell Scientific, UK) instruments have a flat spectral response from 300 to 2800 nm and the cosine effect is less than 3% for solar elevation above 1°. CMP3 and SP1110 sensors are regularly calibrated by comparison with a reference sensor at Kipp&Zonen manufacturer and the differences obtained in percentage are lower than 10%. Direct solar irradiance SRdir was calculated from global SRg and diffuse solar SRdif components (Bilbao et al., 2014):
SRdir = SRg − SRdif
(1)
The air temperature and relative humidity were measured by three HMP60 sensors placed in ventilated shelters at 1.0 m (below the vegetation), 2.0 m (in the middle of the vegetation) and 3.0 m (above the vegetation) inside each greenhouse (Fig. 3). The specifications of the used sensors are listed in Table 1. To assess the comparison between the hot and cold period of the different microclimatic parameters inside the greenhouse, only measurements taken when the sky is clear of cloud were used. All the inside and outside sensors were connected to two data loggers (model CR 3000, Campbell, Shepshed, United Kingdom) on which data were measured every 5 s and the average value was recorded every 10 min.
Exterior Control greenhouse
1000
Photovoltaic greenhouse
900
2
Solar Radiation (W/m )
800 700 600 500 400 300 200 100
r
t
be em Se
pt
A
ug
us
ly Ju
ne Ju
M
ay
pr il A
ar ch M
ry br ua Fe
Ja
nu
ar y
0
Fig. 4. Monthly-averaged of solar radiation: inside the photovoltaic greenhouse, the control greenhouse and outside. 278
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Exterior Control greenhouse
Temperature (°C)
24
24
22
22
20
20
18
18
16
16
14
14
12
12
10
10
8
8
6
6
4
4
2
2
0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 5. Evolution of air temperature: inside the photovoltaic greenhouse, the control greenhouse and in outside from 23–24.02.2018. Photovoltaic greenhouse Exterior Control greenhouse
Temperature (°C)
50
50
45
45
40
40
35
35
30
30
25
25
20
20
15
15
10
10
5
5
0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 6. Evolution of air temperature: inside the photovoltaic greenhouse, the control greenhouse and in outside from 24–25.09.2018.
first harvest to the end of the experiment i.e. the 15th harvest from the two greenhouses (photovoltaic and control). During the first harvest that was done in 23 January, the weight of tomatoes harvested from the control and the shaded greenhouse differed significantly. The values were respectively, 39.24 kg from the control greenhouse and 25.02 kg from the photovoltaic greenhouse. Furthermore, at the last harvest that was done in 25 June, the tomato production of the photovoltaic greenhouse is higher than that of the control greenhouse; it reached respectively 52.8 and 34.8 kg/greenhouse. In order to quantify the effect of the presence of PV panels on the production of tomatoes, we calculated the cumulated yield of tomatoes as a function of the cumulated solar radiation received inside the
always higher than that inside the two greenhouses. By analyzing the Fig. 5, we note that the high value of the relative humidity during the cold period was observed in the control greenhouse 93.1% in average, compared to 91.15% in the photovoltaic greenhouse. The difference between the two greenhouses reaches almost 2%. Furthermore, during the summer period we observed that the relative humidity inside the photovoltaic greenhouse is higher than that in the control greenhouse. The maximum difference between the two greenhouses was 7.74%. 4. Agronomic results Fig. 9 shows the total yield in kg/greenhouse measured from the 279
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Control greenhouse Exterior
Relative humidity (%)
100
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
10
10 0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 7. Evolution of air relative humidity: inside the photovoltaic greenhouse, the control greenhouse and in outside from 23–24.02.2018. Photovoltaic greenhouse Exterior Control greenhouse
Relative humidity (%)
100
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
10
10 0
0 4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 8. Evolution of air relative humidity: inside the photovoltaic greenhouse, the control greenhouse and in outside from 28–29.09.2018.
increase and a decrease in relative humidity under the photovoltaic greenhouse. Conversely, during the hot period, air temperature is low under the photovoltaic greenhouse compared to the control compartment. This effect is due to the shade induced by the photovoltaic panels, which is likely a critical factor on the tomato grown in Mediterranean climate (El Aidy, 1986; El Gizawy et al., 1993). Moreover, the photovoltaic panels play a positive role in reducing excess temperature during the summer season and increases the relative humidity; however, the lower relative humidity and high temperature is unsuitable for tomato cultivation resulting in restricts plant-environment gas exchanges and closure of the stomata thus immediately impacting photosynthesis as well as many physiological processes (Ezzaeri et al., 2018).
photovoltaic greenhouse and we compared them to data from the control greenhouse (Table 3). At the end of the tomato cycle, the ratio of the cumulated tomato yield per the cumulated solar radiation in the photovoltaic greenhouse and in the control one, reaches 13.98 kg/kW/m2, 23.28 kg/kW/m2 respectively. These values highlight the extent of the reduction of the solar radiation on the crop yield under this kind of greenhouses due to the negative effect on the vegetal biomass production.
5. Discussion During the winter season at nighttime, there is a slight temperature 280
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Control greenhouse
70
50
45
45
40
40
35
35
30
30
25
25
20
20
15
15
10
10
9t
8t
7t
6t
5t
h 10 th 11 th 12 th 13 th 14 th 15 th
50
h
55
h
55
h
60
h
60
4t h
65
3r d
65
1s t 2n d
Total yield (kg)
70
Harvest Fig. 9. Comparison between the tonnage in control and photovoltaic greenhouses from the 1st to the 15th harvest.
temperature and humidity variability, with the tomatoes crop for the test. It was found that the photovoltaic modules reduced the availability of solar radiation inside the greenhouse by 64%, compared to the greenhouse without photovoltaic modules, and the tomato yield was decreased compared to the control greenhouse.
Table 3 Cumulated global radiation (kW/m2) and cumulated yield (kg/m2) in terms of days after transplanting, inside the two greenhouses photovoltaic and control. Days after transplanting
104 111 119 125 133 143 150 157 164 170 176 183 197 205 227
Cumulated solar radiation to the tomato yield (kg tomato/ kW solar radiation/m2) Photovoltaic greenhouse
Control greenhouse
1.58 3.51 5.56 6.85 8.04 9.10 9.82 11.60 12.54 13.07 13.50 13.74 13.68 13.84 13.98
4.26 7.24 10.11 13.49 16.44 17.03 18.09 20.79 22.25 22.98 23.22 23.73 23.37 23.46 23.28
6. Conclusion This work provides a comparative study of the climate parameters and the tomato yield during two different periods (cold and hot) in two greenhouses, one with photovoltaic panels and the other without. Moreover, the climate data analysis (global solar radiation, air temperature and relative humidity) during the different seasons provides a good support to better judge the photovoltaic shading effect on crop yield. During the summer period, the photovoltaic panels have the advantage of reducing the temperature inside the greenhouse and sometimes falling in the optimum range for the tomatoes growth. The photovoltaic panels protect the crop from intense solar radiation in summer as they play the role of shading screens. Conversely, during the winter period the photovoltaic panels does not have a significant effect on the microclimate (temperature and relative humidty). In other, the negative effect of the photovoltaic panels during the cold period was manifested in delay of tomato maturity. The results of this study encourage testing other occupancy rate of the photovoltaic panels, analyzing the effect of shade induced by the PV on other crops than tomatoes, and test LED to solve the delay of maturity during the cold period.
The reduction of solar radiation inside the photovoltaic greenhouse during the cold period causes a delay of maturity which explains the big difference in the first harvest between the two greenhouses; furthermore, we can used the LED supplemental lighting to solve the delay of maturity during the cold period. Sun Yi Lee et al. (2014), Julienne Fanwouaa et al. (2019) both found that the use of LED supplemental lighting for tomato cultivation increasing the harvesting profit and improving the tomato fruit quality. Comparing the performance of this experience to those studied by other researchers, we can find that the degree of influence related to the climatic condition, shading degree and distribution format of photovoltaic panels. Ezzaeri et al. (2018), who studied 10% of shade, find that this ratio of coverage during warm month April, does not have any significant effect on the microclimate or on the tomato yield. Cossu et al. (2017) assessed the climate conditions inside a greenhouse east-west oriented with 50% of the roof area was covered by the photovoltaic panels, studying the solar radiation distribution and the
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgment We are grateful to INRA Agadir for support of our experience and we greatly appreciate CNRST (Centre National pour la Recherche 281
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Scientifique et Technique, Morocco) for their financial support.
Marucci, A., Monarca, D., Cecchini, M., Colantoni, A., Manzo, A., Cappuccini, A., 2012. The semitransparent photovoltaic films for Mediterranean greenhouse: a new sustainable technology. Math. Probl. Eng. 14. Marucci, A., Monarca, D., Colantoni, A., Campiglia, E., Cappuccini, A., 2017. Analysis of the internal shading in a photovoltaic greenhouse tunnel. vol. XLVIII. https://doi: 10. 4081/jae.2017.622. Minuto, G., Bruzzone, C., Tinivella, F., Delfino, G., Minuto, A., 2009. Photovoltaics on greenhouse roofs to produce more energy. Inf. Agrar. Suppl. 65, 16–19. Pérez-Alonso, J., Pérez-Garcıa, M., Pasamontes-Romera, M., Callejón-Ferre, A.J., 2012. Performance analysis and neural modelling of a greenhouse integrated photovoltaic system. Renew. Sustain. Energy Rev. 16 4675e4685. Poncet, C., Muller, M.M., Brun, R., Fatnassi, H., 2012. Photovoltaic greenhouses, nonsense or a real opportunity for the greenhouse systems?. pp. 75–80. https://doi: 10. 17660/ActaHortic.927.7. Saifultah, M., Gwak, J., Yun, J.H., 2016. Comprehensive review on material requirements, present status, and future prospects for building-integrated semitransparent photovoltaics (BISTPV). J. Mater. Chem. A 4, 8512–8540. Selvi, S.R., Baskaran, R., 2015. Solar photovoltaic-powered membrane distillation as sustainable clean energy technology in desalination. pp. 1247–1254. Sonneveld, P.J., Holterman, H.J., Swinkels, G.L.A.M., van Tuijl, B.A.J., Bot, G.P.A., 2008. Solar energy delivering greenhouse with an integrated NIR filter. Acta Hortic. 801, 703e710. Sonneveld, P.J., Swinkels, G.L.A.M., Campen, J., Van Tuijl, B.A.J., Janssen, H.J.J., Bot, G.P.A., 2010. Performance results of a solar greenhouse combining electrical and thermal energy production. Biosyst. Eng. 106 (1), 48–57. Sugiura, H., Yano, A., Tsuchiya, K., Iimoto, M., Tagawa, A., 2002. A model experiment for a plastic house ventilator driven by electricity from photovoltaic generators. J. Japanese Soc. Agric. Mach. 64(6), 128e136 (in Japanese with English abstract). Sun Yi, Lee, Kwon, Joon Kook, Park, Kyoung Sub, Choi, Hyo Gil, 2014. The effect of LED light source on the growth and yield of greenhouse grown tomato. Acta Hortic. 1037, 789–793. DOI: 10.17660/ActaHortic.2014.1037.104. Tripathy, M., Kumar, M., Sadhu, P.K., 2017. Photovoltaic system using Lambert W function-based technique. Solar Energy 158 (August), 432–439. Trypanagnostopoulos, G., Kavga, A., Tripanagnostopoulos, Y., 2017. Greenhouse performance results for roof installed photovoltaics. Renew. Energy 2017. https://doi. org/10.1016/j.renene.2017.04.066. Urena-Sanchez, R., Callejón-Ferre, A.J., Pérez-Alonso, J., Carreñ o-Ortega, A., 2012. Greenhouse tomato production with electricity generation by roof-mounted flexible solar panels. Scientia Agricola 69(4), 233e239. U.S. Energy Information Administration, June 2016 Monthly Energy Review. U.S. Department of Energy. Office of Energy Statistics. Washington, DC. Wang, T., Wu, G., Chen, J., Cui, P., Chen, Z., Yan, Y., 2016. Integration of solar technology to modern greenhouse in China: Current status, challenges and prospect. Renew. Sustain. Energy Rev.(November). Xue, J., 2017. Photovoltaic agriculture - New opportunity for photovoltaic applications in China. Renew. Sustain. Energy Rev. 73 (January), 1–9. https://doi.org/10.1016/j. rser.2017.01.098. Yang, F., Zhang, Y., Hao, Y.Y., Cui, Y.X., Wang, W.Y., Ji, T., Shi, F., Wei, B., 2015. Visibly transparent organic photovoltaic with improved transparency and absorption based on tandem photonic crystal for greenhouse application. Appl. Opt. 54, 10232–10239. Yano, A., Tsuchiya, K., Nishi, K., Moriyama, T., Ide, O., Toya, M., 2005. Development of a photovoltaic module as a power source for greenhouse environment control devices and a study on its mounting in a greenhouse. J. Japanese Soc. Agric. Mach. 67 (5), 124e127. Yano, A., Furue, A., Moriyama, T., Ide, O., Tsuchiya, K., 2007. Development of a greenhouse shading screen controller driven by photovoltaic energy. J. Japanese Soc. Agric. Mach. 69(6), 57e64 (in Japanese with English abstract). Yano, A., Kadowaki, M., Furue, A., Tamaki, N., Tanaka, T., Hiraki, E.Y., Kato, F., Ishizu, S., Noda, 2010. Shading and electrical features of a photovoltaic array mounted inside the roof of an east west oriented greenhouse. Biosyst. Eng. 106(4), 367e377. Yano, A., Onoe, M., Najata, J., 2014. Prototype semi-transparent photovoltaic modules for greenhouse roof applications. Biosyst. Eng. 122, 62–73.
References Al-Ibrahim, A., Al-Abbadi, N., Al-Helal, I., 2006. PV greenhouse system e system description, performance and lesson learned. Acta Hortic. 710, 251e264. Al-Shamiry, F.M.S., Ahmad, D., Sharif, A.R.M., Aris, I., Janius, R., Kamaruddin, R., 2007. Design and development of a photovoltaic power system for tropical greenhouse cooling. Am. J. Appl. Sci. 4 (6), 386–389. Bilbao, J., Román, R., Yousif, C., Mateos, D., de Miguel, A., 2014. Total Ozone column, water vapour and aerosol effects on erythemal and global solar irradiance in Marsaxlokk, Malta. Atmos. Environ. https://doi.org/10.1016/j.atmosenv.2014.10. 005. Buttaro, D., Renna, M., Gerardi, C., Blando, F., Santamaria, P., Serio, F., 2016. Soilles production of wild rocket as affected by greenhouse coverage with photovoltaic modules. Acta Sci. Pol.-Hortic Cultus 15, 129–142. Castellano, S., Santamaria, P., Serio, F., 2016. Solar radiation distribution inside a monospan greenhouse with the roof entirely covered by photovoltaic panels. Vol. XLVII, pp. 1–6, https://doi.org/10.4081/jae.2016.485. Cossu, M., Yano, A., Li, Z., Onoe, M., Nakamura, H., Matsumoto, T., Nakata, J., 2016. Advances on the semi-transparent modules based on micro solar cells: First integration in a greenhouse system. Appl. Energy 162, 1042–1051. Cossu, M., Luigi Ledda, Giulia Urracci, Antonella Sirigu, Andrea Cossu, LeliaMurgia, Antonio Pazzona, Akira Yano, 2017. An algorithm for the calculation of the light distribution in photovoltaic greenhouses. Solar Energy 141, pp. 38–48. El Aidy, F., 1986. Tomato production under simple protective tunnels in Egypt. Acta Hort. 190, 511–514. https://doi.org/10.17660/ActaHortic. 190.58. El Gizawy, A.M., Abdallah, M.M.F., Gomaa, H.M., Mohamed, S.S., 1993. Effect of different shading levels on tomato plants: Yield and fruit quality. Acta Hort. 323, 349–354. El-khatib, M.F., Shaaban, S., El-sebah, M.I.A., 2017. A proposed advanced maximum power point tracking control for a photovoltaic-solar pump system. Solar Energy 158 (September), 321–331. Esen, M., Yuksel, T., 2013. Experimental evaluation of using various renewable energy sources for heating a greenhouse. Energy Build. 65, 340–351. https://doi.org/10. 1016/j.enbuild.2013.06.018. Ezzaeri, K., Fatnassi, H., Bouharroud, R., Gourdo, L., Bazgaou, A., Wifaya, A., Demrati, H., Bekkaoui, A., Aharoune, A., Poncet, C., Bouirden, L., 2018. The effect of photovoltaic panels on the microclimate and on the tomato production under photovoltaic canarian greenhouses. Sol. Energy 173, 1126–1134. https://doi.org/10.1016/j.solener. 2018.08.043. Ezzaeri, K., Fatnassi, H., Bouharroud, R., Poncet, C., Bouirden, L., 2019a. Microclimate and tomato production under canarian greenhouse equipped with flexible photovoltaic panels. Acta Hort. (article accepted in April 2019) http://www.ihc2018.org/ en/S17.html. Ezzaeri, K., Fantassi, H., Bouirden, L., Aharoune, A., 2019b. Spatial distribution of air temperature and solar radiation in the Canarian photovoltaic greenhouse in arid climates. International Meeting on Advanced Technologies in Energy and Electrical Engineering 2018, http://doi.org/10.5339/qproc.2019.imat3e2018.13. Fanwoua, J., Vercambre, G., Buck-Sorlin, G., Dieleman, J.A., de Visser, P., Génard, M., 2019. Supplemental LED lighting affects the dynamics of tomato fruit growth and composition. Sci. Hortic. 256, 108571. https://doi.org/10.1016/j.scienta.2019. 108571. Fatnassi, H., Poncet, Ch., Bazzano, M.M., Brun, R., Bertin, N., 2015. A numerical simulation of the photovoltaic greenhouse microclimate. Sol. Energy 120, 575–584. https://doi.org/10.1016/j.solener.2015.07.019. IPCC, 2011. IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Prepared by Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kadowaki, M., Yano, A., Ishizu, F., Tanaka, T., Noda, S., 2012. Effects of greenhouse photovoltaic array shading on Welsh onion growth. Biosyst. Eng. 111 (3), 290e297.
282
Contents lists available at ScienceDirect
Solar Energy journal homepage: www.elsevier.com/locate/solener
Performance of photovoltaic canarian greenhouse: A comparison study between summer and winter seasons
T
⁎
K. Ezzaeria, , H. Fatnassib, A. Wifayac, A. Bazgaoua, A. Aharounea, C. Poncetb, A. Bekkaouid, L. Bouirdena a
Thermodynamics and Energetic Laboratory, Faculty of Sciences, Agadir, Morocco Université Côte d'Azur, INRA, CNRS, ISA, France c Regional Centre of Agricultural Research, Agadir, Morocco d Mechanization Agricultural Department, IAV Hassan II, Rabat, Morocco b
A R T I C LE I N FO
A B S T R A C T
Keywords: Flexible photovoltaic panels South Mediterranean area Tomatoes Microclimate Shading Renewable energy
A large-scale use of the renewable energy in agriculture has become an optimal way to successfully deal with the issues of sustainability and climate change. Recently, the integration of solar panels on the roof of the greenhouse gave birth to a new crop production system called photovoltaic greenhouse. In this paper, we investigated the shading effect of the flexible photovoltaic panels, mounted on the greenhouse roof area in the checkerboard format, on the microclimate and the tomatoes yield during the summer and winter period. This study was undertaken in a two tomato canarian greenhouses, typical of the south Mediterranean region. The results of our study showed that the photovoltaic panels covering 40% roof area of the canary type greenhouse does not have a significant effect on the climatic parameters. Additionally, during the hot period, the photovoltaic panels reduced the temperature inside the greenhouse and sometimes falling in the optimum range for the tomatoes growth. Furthermore, this occupancy rate of the photovoltaic panels does not have a significant effect on the overall yield of tomatoes.
1. Introduction In recent decades, the cultivation of horticultural plants in greenhouses, knew a growing throughout the world. The reason for this development is due to population growth and the increased demand for fresh produce throughout the year. Nevertheless, this agro-system is threatened by several recent evolutions that weaken it. One of the major problems facing by the producers, is the significant increase of the price in energy. For that, the farmers who want to remain competitive must invest at the same time in the greenhouse agricultural production and other production e.g. the photovoltaic electrical production. The photovoltaic energy is an attractive renewable energy among electrical power resources (Ezzaeri et al., 2019a), because it is abundant, free (Tripathy et al., 2017), and have less environmental impact (Selvi and Baskaran, 2015; El-khatib et al., 2017). However, with the generous government subsidies allocated to conversion to clean energy in agriculture, agricultural lands experienced the invasion of the photovoltaic installations in recent years (IPCC, 2011; U.S. Energy Information Administration, 2016). To resolve
⁎
this energy-food conflict, it is more judicious to combine these two production systems under the same area (Ezzaeri et al., 2018; Wang et al., 2016; Xue, 2017; Esen et al., 2013). The fundamental challenge of this technology is to maintain a higher quality of agricultural produce and a lower impact on the environment (Poncet et al., 2012). The challenge is, therefore, to arrive to a real photons sharing between electrical production and crops to allow profitable agricultural activity (Ezzaeri et al., 2019b). The spectrum sunlight ranging from 400 nm to 700 nm is exactly what plants needs for the photosynthesis process, and wavelengths more than 700 nm could be useful for other than photosynthesis (Sonneveld et al., 2010; Yano et al., 2007). Several research studies have been conducted on the greenhouses equipped by flexible and semi-transparent photovoltaic panels (Marucci et al., 2012; Yano et al., 2014; Yang et al., 2015; Buttaro et al., 2016; Cossu et al., 2016; Minuto et al., 2009; Sugiura et al., 2002; UrenaSanchez et al., 2012; Yano et al., 2007; Kadowaki et al., 2012; Saifultah et al., 2016). Trypanagnostopoulos et al. (2017) studied the performance results of energy production and lettuce plant growing inside the greenhouse
Corresponding author.
https://doi.org/10.1016/j.solener.2020.01.057 Received 12 September 2019; Received in revised form 17 January 2020; Accepted 21 January 2020 0038-092X/ © 2020 Published by Elsevier Ltd on behalf of International Solar Energy Society.
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Fig. 1. Photos of the photovoltaic and the control greenhouses.
system under two seasons winter and summer i.e. when the intensity of solar radiation is at these two extremes (weak and strong). (iii) Also new, installing the PV panels on 40% of the roof surface of the greenhouse represents special challenge since there is a risk of affecting the crop production under this kind of greenhouse. Therefore, the paper results can be useful for farmers in south Mediterranean region to measure the maturity level of this innovative agro-system and to see if they can achieve a balance between crop and photovoltaic electricity production.
when 20% of their roof area was occupied by the photovoltaic panels’ pc-Si type. The results showed that the photovoltaic panels produced 50.83 kWh m−2 for the characteristic cultivation period of Feb-MarApr, and the lettuce plants growing results under the shading effect were satisfactory. Marucci et al. (2017) analysed the variation of shading under a tunnel greenhouse provoked by the flexible and transparent photovoltaic panels in a checkerboard arrangement. The results show some regularity in the shading percentage, mainly due to the format greenhouse, the shading in the middle of the day is almost always under the tunnel greenhouse, from mid-March to mid-September, and partly outside partly inside the greenhouse in the other months of the year. Castellano et al. (2016) investigated experimentally and numerically the variation over space and time of the amount photosynthetic photons flux density inside a mono-span greenhouse their roof entirely covered by the polycrystalline photovoltaic panels, the analysis showed a good capability of the numerical model to predict the shading effect under a photovoltaic greenhouse. Al-Shamiry et al. (2007) studied photovoltaic hybrid system for cooling a tropical greenhouse, this system includes 48 photovoltaic solar Panels with 18.75 W each, one inverter, 1 charge controller and a battery bank (including 12 batteries). The PV system is located at University Putra Malaysia (UPM) Research Park. The national electricity grid was used as a backup unit. The load consisted of two misting fans for cooling greenhouse (during test period time) with 400 W electric power and five hours (11:00 am to 16:00 pm) daily operation. The results showed that the photovoltaic system would be suitable to supply electricity to cover the loads requirement demands without using energy from the grid. Sonneveld et al. (2010) proposed a new type of greenhouse, which combines reflection of near infrared radiation with electrical power generation using hybrid photovoltaic cell/thermal collector modules. The experimental results with the electricity-producing greenhouse prototype prove that part of the near infrared radiation can be converted into useful electrical and thermal energy. The reflected near infrared radiation can be focused with a circular trough reflector integrated in the greenhouse cover resulting in a geometrical concentration factor of 30. An electrical peak power of approximately 30 Wm−2 and a thermal peak power of 121 Wm−2 are expected with an illumination of 900 Wm−2. Previous photovoltaic greenhouse studies have commonly used conventional flat or planar flexible photovoltaic panels (Urena-Sanchez et al., 2012; Yano et al., 2010; Sugiura et al., 2002; Sonneveld et al., 2008; Alonso et al., 2012; Yano et al., 2007; Kadowaki et al., 2012; Al-Ibrahim et al., 2006; Yano et al., 2005). In this context, this work aims to assess the shading effect of the flexible photovoltaic panels, mounted on 40% of the canarian greenhouse roof area, on the microclimate and the crop yield during summer and winter periods. The novelty of this study is threefold: (i) It presents a first application of the PV panels on the canarian greenhouses i.e. greenhouses widespread in the south Mediterranean region. (ii) It evaluates this
2. Materials and methods 2.1. Site The measurement campaigns were performed from January to June 2018 in the Regional Center for Agricultural Research INRA in southern Agadir (Latitude: 30° 13′ N, Longitude: 9° 23′ W, Altitude: 80 m) on the Atlantic coast of Morocco where the weather is moderate. During winter season, the weather in this region is not so cold, the minimal daytime winter temperatures is around 11 °C. 2.2. Greenhouse description The measurements were carried out in two identical North- South oriented canarian greenhouses, were located along their common North-South axis with 7 m separation. Each greenhouse occupies a surface area of 172 m2, with the dimensions, 11.0 m wide, 15.6 m long, 4.0 m gutter height, 5.0 m in the ridge and a roof slope of 10°. The greenhouses cover material was a plastic polyethylene film with 200 µm of thickness and 75% of light transmission. The ventilation was provided by manually opened side equipped with insect-proof nets. One of the two greenhouses was covered by opaque photovoltaic panels and the second without. As shown in Fig. 1, 132 opaque photovoltaic panels were fixed on the roof of the greenhouse at tilted angle of 10°, placed in checkerboard format to promote the solar radiation transmission (Fatnassi et al., 2015). Each photovoltaic module has the following dimensions: 1000 mm × 500 mm × 3 mm (Table 2). The photovoltaic panels were located at 3 cm over the plastic cover to allow air to circulate circulation between the panels and the plastic cover. 2.3. Crop Tomato (Solanum lycopersicum, cultivar: Pristyla, Rijk Zwaan Company) were planted on October, 11th 2017 in pots, with a density 0.7 plants/m2, there were 40 pots divided in four rows, each row contains 10 pots, each pot had three plants. The distance between rows was 120 cm and between plants was 30 cm. All tomato plants get the same drip irrigation quantity. The agronomic parameters measurements were plants height, leaf area, steam diameter and number of leaves inside the photovoltaic and control greenhouses. Six tomato plants were picked in each row. The planting rows inside the two greenhouses are 276
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Fig. 2. Location of the photovoltaic greenhouse in the experimental field, and the positioning of each pyranometer in this greenhouse.
Fig. 3. Section of the experimental greenhouse and the location of the experimental sensors used in the present experience.
oriented North-South, perpendicular to the wind direction.
Table 1 Specification of the instruments. Instrument name
Measurement range
Accuracy
2.4. Microclimate monitoring
Pyranometer Kipp&zonen CMP11 Pyranometer SP1110 Vaisala HMP60
0–2000 W/m2 0–3000 W/m2 T: −40 °C to +60 °C RH: 0–100%
± 5% ± 5% ± 0.6 °C ± 5%
Microclimate variables such as temperature, relative humidity, solar radiation, were measured on the two greenhouses i.e. photovoltaic and control, throughout a crop cycle from January 3, to September 24, 2018. In addition, meteorological data were measured by an external weather station. The solar radiation was measured in nine locations in the 277
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
3. Observations and results
Table 2 Characteristics of the photovoltaic panels. Name
MX-FLEX Protect
Peak power (Pmax) Open Circuit Voltage (Voc) Short circuit Current (Icc) Voltage (Vmp) Current (Imp) dimensions Weight Module efficiency
100Wc 23.4 V 5.4 A 19.8 V 5.05 A 1000 × 500 × 3 mm 1.7 kg 19%
Fig. 4 shows the variation of global solar radiation inside and outside the two greenhouses during nine months. The analysis of theses graphs shows that the high value of solar radiation was detected during July when the mean of the external global radiation is 949.11 W/m2. These values are respectively 617.37 W/m2 and 305.13 W/m2inside the control and the photovoltaic greenhouse, which presents a reduction of 50.50% of the solar radiation due to the presence of the PV panels, compared to the control greenhouse. This value drops to 41% during the cold period in January. Figs. 5 and 6 show the variation of air temperature during the cold and hot period inside and outside the two greenhouses (photovoltaic and control). Based on these two figures we can see that the temperature inside the two greenhouses follows an almost sinusoidal evolution; the difference of air temperature between the shaded and unshaded greenhouse was higher during summer, the temperature was higher in the unshaded greenhouse by 8% compared to the shaded greenhouse, due to the presence of photovoltaic panels, therefore, during the winter season the air temperature inside the photovoltaic and control greenhouses is almost at the same level, the high values of the temperature inside the photovoltaic greenhouse was 23.93 °C and inside the control greenhouse was 23.51 °C, the maximum difference between the two greenhouses reach a values of 0.75 °C. This small difference of air temperature is due to the photovoltaic panels shading which causes an accumulation of solar radiation inside the greenhouse, which led to a slight rise in air temperature. During the summer period, it appears a difference between the temperatures of the two greenhouses in daytime. The high values were detected in the control greenhouse vary between [46.81 °C, 48.37 °C] compared to the photovoltaic greenhouse [43.78 °C, 44.68 °C] representing a high difference reaches 3.69 °C between the two greenhouses. Figs. 7 and 8 shows the variation of relative humidity inside and outside the two greenhouses during the cold and hot period. The relative humidity in the two greenhouses does not show great variations during the night for the cold or the hot period. Outside temperature is
photovoltaic greenhouse (Fig. 2) and in one location in the control greenhouse using nine pyranometers CMP3 and SP1110 (Campbell Scientific Ltd. UK) positioned at 3 m above the ground level. The CMP3 (Kipp&Zonen, Campbell Scientific, UK) instruments have a flat spectral response from 300 to 2800 nm and the cosine effect is less than 3% for solar elevation above 1°. CMP3 and SP1110 sensors are regularly calibrated by comparison with a reference sensor at Kipp&Zonen manufacturer and the differences obtained in percentage are lower than 10%. Direct solar irradiance SRdir was calculated from global SRg and diffuse solar SRdif components (Bilbao et al., 2014):
SRdir = SRg − SRdif
(1)
The air temperature and relative humidity were measured by three HMP60 sensors placed in ventilated shelters at 1.0 m (below the vegetation), 2.0 m (in the middle of the vegetation) and 3.0 m (above the vegetation) inside each greenhouse (Fig. 3). The specifications of the used sensors are listed in Table 1. To assess the comparison between the hot and cold period of the different microclimatic parameters inside the greenhouse, only measurements taken when the sky is clear of cloud were used. All the inside and outside sensors were connected to two data loggers (model CR 3000, Campbell, Shepshed, United Kingdom) on which data were measured every 5 s and the average value was recorded every 10 min.
Exterior Control greenhouse
1000
Photovoltaic greenhouse
900
2
Solar Radiation (W/m )
800 700 600 500 400 300 200 100
r
t
be em Se
pt
A
ug
us
ly Ju
ne Ju
M
ay
pr il A
ar ch M
ry br ua Fe
Ja
nu
ar y
0
Fig. 4. Monthly-averaged of solar radiation: inside the photovoltaic greenhouse, the control greenhouse and outside. 278
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Exterior Control greenhouse
Temperature (°C)
24
24
22
22
20
20
18
18
16
16
14
14
12
12
10
10
8
8
6
6
4
4
2
2
0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 5. Evolution of air temperature: inside the photovoltaic greenhouse, the control greenhouse and in outside from 23–24.02.2018. Photovoltaic greenhouse Exterior Control greenhouse
Temperature (°C)
50
50
45
45
40
40
35
35
30
30
25
25
20
20
15
15
10
10
5
5
0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 6. Evolution of air temperature: inside the photovoltaic greenhouse, the control greenhouse and in outside from 24–25.09.2018.
first harvest to the end of the experiment i.e. the 15th harvest from the two greenhouses (photovoltaic and control). During the first harvest that was done in 23 January, the weight of tomatoes harvested from the control and the shaded greenhouse differed significantly. The values were respectively, 39.24 kg from the control greenhouse and 25.02 kg from the photovoltaic greenhouse. Furthermore, at the last harvest that was done in 25 June, the tomato production of the photovoltaic greenhouse is higher than that of the control greenhouse; it reached respectively 52.8 and 34.8 kg/greenhouse. In order to quantify the effect of the presence of PV panels on the production of tomatoes, we calculated the cumulated yield of tomatoes as a function of the cumulated solar radiation received inside the
always higher than that inside the two greenhouses. By analyzing the Fig. 5, we note that the high value of the relative humidity during the cold period was observed in the control greenhouse 93.1% in average, compared to 91.15% in the photovoltaic greenhouse. The difference between the two greenhouses reaches almost 2%. Furthermore, during the summer period we observed that the relative humidity inside the photovoltaic greenhouse is higher than that in the control greenhouse. The maximum difference between the two greenhouses was 7.74%. 4. Agronomic results Fig. 9 shows the total yield in kg/greenhouse measured from the 279
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Control greenhouse Exterior
Relative humidity (%)
100
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
10
10 0
0 0
4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 7. Evolution of air relative humidity: inside the photovoltaic greenhouse, the control greenhouse and in outside from 23–24.02.2018. Photovoltaic greenhouse Exterior Control greenhouse
Relative humidity (%)
100
100
90
90
80
80
70
70
60
60
50
50
40
40
30
30
20
20
10
10 0
0 4
8
12
16
20
24
28
32
36
40
44
48
Time (h) Fig. 8. Evolution of air relative humidity: inside the photovoltaic greenhouse, the control greenhouse and in outside from 28–29.09.2018.
increase and a decrease in relative humidity under the photovoltaic greenhouse. Conversely, during the hot period, air temperature is low under the photovoltaic greenhouse compared to the control compartment. This effect is due to the shade induced by the photovoltaic panels, which is likely a critical factor on the tomato grown in Mediterranean climate (El Aidy, 1986; El Gizawy et al., 1993). Moreover, the photovoltaic panels play a positive role in reducing excess temperature during the summer season and increases the relative humidity; however, the lower relative humidity and high temperature is unsuitable for tomato cultivation resulting in restricts plant-environment gas exchanges and closure of the stomata thus immediately impacting photosynthesis as well as many physiological processes (Ezzaeri et al., 2018).
photovoltaic greenhouse and we compared them to data from the control greenhouse (Table 3). At the end of the tomato cycle, the ratio of the cumulated tomato yield per the cumulated solar radiation in the photovoltaic greenhouse and in the control one, reaches 13.98 kg/kW/m2, 23.28 kg/kW/m2 respectively. These values highlight the extent of the reduction of the solar radiation on the crop yield under this kind of greenhouses due to the negative effect on the vegetal biomass production.
5. Discussion During the winter season at nighttime, there is a slight temperature 280
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Photovoltaic greenhouse Control greenhouse
70
50
45
45
40
40
35
35
30
30
25
25
20
20
15
15
10
10
9t
8t
7t
6t
5t
h 10 th 11 th 12 th 13 th 14 th 15 th
50
h
55
h
55
h
60
h
60
4t h
65
3r d
65
1s t 2n d
Total yield (kg)
70
Harvest Fig. 9. Comparison between the tonnage in control and photovoltaic greenhouses from the 1st to the 15th harvest.
temperature and humidity variability, with the tomatoes crop for the test. It was found that the photovoltaic modules reduced the availability of solar radiation inside the greenhouse by 64%, compared to the greenhouse without photovoltaic modules, and the tomato yield was decreased compared to the control greenhouse.
Table 3 Cumulated global radiation (kW/m2) and cumulated yield (kg/m2) in terms of days after transplanting, inside the two greenhouses photovoltaic and control. Days after transplanting
104 111 119 125 133 143 150 157 164 170 176 183 197 205 227
Cumulated solar radiation to the tomato yield (kg tomato/ kW solar radiation/m2) Photovoltaic greenhouse
Control greenhouse
1.58 3.51 5.56 6.85 8.04 9.10 9.82 11.60 12.54 13.07 13.50 13.74 13.68 13.84 13.98
4.26 7.24 10.11 13.49 16.44 17.03 18.09 20.79 22.25 22.98 23.22 23.73 23.37 23.46 23.28
6. Conclusion This work provides a comparative study of the climate parameters and the tomato yield during two different periods (cold and hot) in two greenhouses, one with photovoltaic panels and the other without. Moreover, the climate data analysis (global solar radiation, air temperature and relative humidity) during the different seasons provides a good support to better judge the photovoltaic shading effect on crop yield. During the summer period, the photovoltaic panels have the advantage of reducing the temperature inside the greenhouse and sometimes falling in the optimum range for the tomatoes growth. The photovoltaic panels protect the crop from intense solar radiation in summer as they play the role of shading screens. Conversely, during the winter period the photovoltaic panels does not have a significant effect on the microclimate (temperature and relative humidty). In other, the negative effect of the photovoltaic panels during the cold period was manifested in delay of tomato maturity. The results of this study encourage testing other occupancy rate of the photovoltaic panels, analyzing the effect of shade induced by the PV on other crops than tomatoes, and test LED to solve the delay of maturity during the cold period.
The reduction of solar radiation inside the photovoltaic greenhouse during the cold period causes a delay of maturity which explains the big difference in the first harvest between the two greenhouses; furthermore, we can used the LED supplemental lighting to solve the delay of maturity during the cold period. Sun Yi Lee et al. (2014), Julienne Fanwouaa et al. (2019) both found that the use of LED supplemental lighting for tomato cultivation increasing the harvesting profit and improving the tomato fruit quality. Comparing the performance of this experience to those studied by other researchers, we can find that the degree of influence related to the climatic condition, shading degree and distribution format of photovoltaic panels. Ezzaeri et al. (2018), who studied 10% of shade, find that this ratio of coverage during warm month April, does not have any significant effect on the microclimate or on the tomato yield. Cossu et al. (2017) assessed the climate conditions inside a greenhouse east-west oriented with 50% of the roof area was covered by the photovoltaic panels, studying the solar radiation distribution and the
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgment We are grateful to INRA Agadir for support of our experience and we greatly appreciate CNRST (Centre National pour la Recherche 281
Solar Energy 198 (2020) 275–282
K. Ezzaeri, et al.
Scientifique et Technique, Morocco) for their financial support.
Marucci, A., Monarca, D., Cecchini, M., Colantoni, A., Manzo, A., Cappuccini, A., 2012. The semitransparent photovoltaic films for Mediterranean greenhouse: a new sustainable technology. Math. Probl. Eng. 14. Marucci, A., Monarca, D., Colantoni, A., Campiglia, E., Cappuccini, A., 2017. Analysis of the internal shading in a photovoltaic greenhouse tunnel. vol. XLVIII. https://doi: 10. 4081/jae.2017.622. Minuto, G., Bruzzone, C., Tinivella, F., Delfino, G., Minuto, A., 2009. Photovoltaics on greenhouse roofs to produce more energy. Inf. Agrar. Suppl. 65, 16–19. Pérez-Alonso, J., Pérez-Garcıa, M., Pasamontes-Romera, M., Callejón-Ferre, A.J., 2012. Performance analysis and neural modelling of a greenhouse integrated photovoltaic system. Renew. Sustain. Energy Rev. 16 4675e4685. Poncet, C., Muller, M.M., Brun, R., Fatnassi, H., 2012. Photovoltaic greenhouses, nonsense or a real opportunity for the greenhouse systems?. pp. 75–80. https://doi: 10. 17660/ActaHortic.927.7. Saifultah, M., Gwak, J., Yun, J.H., 2016. Comprehensive review on material requirements, present status, and future prospects for building-integrated semitransparent photovoltaics (BISTPV). J. Mater. Chem. A 4, 8512–8540. Selvi, S.R., Baskaran, R., 2015. Solar photovoltaic-powered membrane distillation as sustainable clean energy technology in desalination. pp. 1247–1254. Sonneveld, P.J., Holterman, H.J., Swinkels, G.L.A.M., van Tuijl, B.A.J., Bot, G.P.A., 2008. Solar energy delivering greenhouse with an integrated NIR filter. Acta Hortic. 801, 703e710. Sonneveld, P.J., Swinkels, G.L.A.M., Campen, J., Van Tuijl, B.A.J., Janssen, H.J.J., Bot, G.P.A., 2010. Performance results of a solar greenhouse combining electrical and thermal energy production. Biosyst. Eng. 106 (1), 48–57. Sugiura, H., Yano, A., Tsuchiya, K., Iimoto, M., Tagawa, A., 2002. A model experiment for a plastic house ventilator driven by electricity from photovoltaic generators. J. Japanese Soc. Agric. Mach. 64(6), 128e136 (in Japanese with English abstract). Sun Yi, Lee, Kwon, Joon Kook, Park, Kyoung Sub, Choi, Hyo Gil, 2014. The effect of LED light source on the growth and yield of greenhouse grown tomato. Acta Hortic. 1037, 789–793. DOI: 10.17660/ActaHortic.2014.1037.104. Tripathy, M., Kumar, M., Sadhu, P.K., 2017. Photovoltaic system using Lambert W function-based technique. Solar Energy 158 (August), 432–439. Trypanagnostopoulos, G., Kavga, A., Tripanagnostopoulos, Y., 2017. Greenhouse performance results for roof installed photovoltaics. Renew. Energy 2017. https://doi. org/10.1016/j.renene.2017.04.066. Urena-Sanchez, R., Callejón-Ferre, A.J., Pérez-Alonso, J., Carreñ o-Ortega, A., 2012. Greenhouse tomato production with electricity generation by roof-mounted flexible solar panels. Scientia Agricola 69(4), 233e239. U.S. Energy Information Administration, June 2016 Monthly Energy Review. U.S. Department of Energy. Office of Energy Statistics. Washington, DC. Wang, T., Wu, G., Chen, J., Cui, P., Chen, Z., Yan, Y., 2016. Integration of solar technology to modern greenhouse in China: Current status, challenges and prospect. Renew. Sustain. Energy Rev.(November). Xue, J., 2017. Photovoltaic agriculture - New opportunity for photovoltaic applications in China. Renew. Sustain. Energy Rev. 73 (January), 1–9. https://doi.org/10.1016/j. rser.2017.01.098. Yang, F., Zhang, Y., Hao, Y.Y., Cui, Y.X., Wang, W.Y., Ji, T., Shi, F., Wei, B., 2015. Visibly transparent organic photovoltaic with improved transparency and absorption based on tandem photonic crystal for greenhouse application. Appl. Opt. 54, 10232–10239. Yano, A., Tsuchiya, K., Nishi, K., Moriyama, T., Ide, O., Toya, M., 2005. Development of a photovoltaic module as a power source for greenhouse environment control devices and a study on its mounting in a greenhouse. J. Japanese Soc. Agric. Mach. 67 (5), 124e127. Yano, A., Furue, A., Moriyama, T., Ide, O., Tsuchiya, K., 2007. Development of a greenhouse shading screen controller driven by photovoltaic energy. J. Japanese Soc. Agric. Mach. 69(6), 57e64 (in Japanese with English abstract). Yano, A., Kadowaki, M., Furue, A., Tamaki, N., Tanaka, T., Hiraki, E.Y., Kato, F., Ishizu, S., Noda, 2010. Shading and electrical features of a photovoltaic array mounted inside the roof of an east west oriented greenhouse. Biosyst. Eng. 106(4), 367e377. Yano, A., Onoe, M., Najata, J., 2014. Prototype semi-transparent photovoltaic modules for greenhouse roof applications. Biosyst. Eng. 122, 62–73.
References Al-Ibrahim, A., Al-Abbadi, N., Al-Helal, I., 2006. PV greenhouse system e system description, performance and lesson learned. Acta Hortic. 710, 251e264. Al-Shamiry, F.M.S., Ahmad, D., Sharif, A.R.M., Aris, I., Janius, R., Kamaruddin, R., 2007. Design and development of a photovoltaic power system for tropical greenhouse cooling. Am. J. Appl. Sci. 4 (6), 386–389. Bilbao, J., Román, R., Yousif, C., Mateos, D., de Miguel, A., 2014. Total Ozone column, water vapour and aerosol effects on erythemal and global solar irradiance in Marsaxlokk, Malta. Atmos. Environ. https://doi.org/10.1016/j.atmosenv.2014.10. 005. Buttaro, D., Renna, M., Gerardi, C., Blando, F., Santamaria, P., Serio, F., 2016. Soilles production of wild rocket as affected by greenhouse coverage with photovoltaic modules. Acta Sci. Pol.-Hortic Cultus 15, 129–142. Castellano, S., Santamaria, P., Serio, F., 2016. Solar radiation distribution inside a monospan greenhouse with the roof entirely covered by photovoltaic panels. Vol. XLVII, pp. 1–6, https://doi.org/10.4081/jae.2016.485. Cossu, M., Yano, A., Li, Z., Onoe, M., Nakamura, H., Matsumoto, T., Nakata, J., 2016. Advances on the semi-transparent modules based on micro solar cells: First integration in a greenhouse system. Appl. Energy 162, 1042–1051. Cossu, M., Luigi Ledda, Giulia Urracci, Antonella Sirigu, Andrea Cossu, LeliaMurgia, Antonio Pazzona, Akira Yano, 2017. An algorithm for the calculation of the light distribution in photovoltaic greenhouses. Solar Energy 141, pp. 38–48. El Aidy, F., 1986. Tomato production under simple protective tunnels in Egypt. Acta Hort. 190, 511–514. https://doi.org/10.17660/ActaHortic. 190.58. El Gizawy, A.M., Abdallah, M.M.F., Gomaa, H.M., Mohamed, S.S., 1993. Effect of different shading levels on tomato plants: Yield and fruit quality. Acta Hort. 323, 349–354. El-khatib, M.F., Shaaban, S., El-sebah, M.I.A., 2017. A proposed advanced maximum power point tracking control for a photovoltaic-solar pump system. Solar Energy 158 (September), 321–331. Esen, M., Yuksel, T., 2013. Experimental evaluation of using various renewable energy sources for heating a greenhouse. Energy Build. 65, 340–351. https://doi.org/10. 1016/j.enbuild.2013.06.018. Ezzaeri, K., Fatnassi, H., Bouharroud, R., Gourdo, L., Bazgaou, A., Wifaya, A., Demrati, H., Bekkaoui, A., Aharoune, A., Poncet, C., Bouirden, L., 2018. The effect of photovoltaic panels on the microclimate and on the tomato production under photovoltaic canarian greenhouses. Sol. Energy 173, 1126–1134. https://doi.org/10.1016/j.solener. 2018.08.043. Ezzaeri, K., Fatnassi, H., Bouharroud, R., Poncet, C., Bouirden, L., 2019a. Microclimate and tomato production under canarian greenhouse equipped with flexible photovoltaic panels. Acta Hort. (article accepted in April 2019) http://www.ihc2018.org/ en/S17.html. Ezzaeri, K., Fantassi, H., Bouirden, L., Aharoune, A., 2019b. Spatial distribution of air temperature and solar radiation in the Canarian photovoltaic greenhouse in arid climates. International Meeting on Advanced Technologies in Energy and Electrical Engineering 2018, http://doi.org/10.5339/qproc.2019.imat3e2018.13. Fanwoua, J., Vercambre, G., Buck-Sorlin, G., Dieleman, J.A., de Visser, P., Génard, M., 2019. Supplemental LED lighting affects the dynamics of tomato fruit growth and composition. Sci. Hortic. 256, 108571. https://doi.org/10.1016/j.scienta.2019. 108571. Fatnassi, H., Poncet, Ch., Bazzano, M.M., Brun, R., Bertin, N., 2015. A numerical simulation of the photovoltaic greenhouse microclimate. Sol. Energy 120, 575–584. https://doi.org/10.1016/j.solener.2015.07.019. IPCC, 2011. IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation. Prepared by Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kadowaki, M., Yano, A., Ishizu, F., Tanaka, T., Noda, S., 2012. Effects of greenhouse photovoltaic array shading on Welsh onion growth. Biosyst. Eng. 111 (3), 290e297.
282