研究目的
To calculate the solar light distribution in a photovoltaic (PV) greenhouse where the entire roof area is covered with PV panels (100% cover ratio) and to validate the simulated data through measurements inside a PV greenhouse complex.
研究成果
The light distribution inside a greenhouse with 100% PV cover ratio is strongly penalised by PV array on the roof: only 33% of the natural solar light is available during the year, compared to the same greenhouse without PV panels on the roof. This percentage decreased to 23% in the central part of the greenhouse area. The light distribution map highlighted the most penalised areas (north side wall of the greenhouse) receiving less than 20% of the potential global radiation inside a conventional greenhouse.
研究不足
The variability of the light distribution on the PV greenhouse area was mainly in the transversal direction (north-south), thus along the width of the greenhouse (CV of 25% on yearly basis). This variability was slightly higher in summer (up to 31% in July), but remained almost constant during the year. The variability on the longitudinal direction (east-west), thus along the length of the greenhouse, was negligible during the year (1%).
1:Experimental Design and Method Selection:
The algorithm calculates the position of the sun compared to that of the PV panels and determines whether the sun is shaded by the PV array on the roof. The solar coordinates of the sun were determined at the specific location of the PV greenhouse on hourly basis.
2:Sample Selection and Data Sources:
The validation of the algorithm was conducted by determining the R2 coefficient and the root mean square error (RMSE), obtained from the comparison between the calculated data and the measurements performed inside the PV greenhouse through a pyranometer.
3:List of Experimental Equipment and Materials:
HOBO Silicon Pyranometer Sensor w/ 3m Cable - cod. S-LIB-M003; Onset Computer Corporation, Bourne, USA.
4:Experimental Procedures and Operational Workflow:
The measurements were conducted at 15 min interval for two months (from April 20, 2016 to June 20, 2016) and the sensor was moved from the first to the final position when at least two days with clear sky were collected.
5:Data Analysis Methods:
The output data of the simulations were expressed as the percentage ratio (GGR) between the mean cumulated yearly global radiation on the OPs (IGP) and the cumulated greenhouse global radiation without PV panels on the roof (IG).
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