Evaluation of photovoltaic performance integrated with shading system in optimizing building energy consumption in hot arid climates (Case study: an office building in Shiraz)

Photovoltaic-integrated Shading systems, are multifunctional components to generate electricity and simultaneously provide the shade needed for building surfaces and walls. Applying integrated photovoltaic systems with building components, including fixed shadings, in addition to regulating the penetration of sunlight and saving energy, seems to be a fully functional approach due to the production of part of the buildings' energy. Therefore, to evaluate the performance of Photovoltaic-integrated Shading systems, in optimizing energy consumption, the need to study the effect of Photovoltaic-integrated Shading systems, on energy in Shiraz was considered. Therefore, 15 Photovoltaic-integrated Shading systems scenarios for the facade of an office space model were calculated using the DesignBuilder simulation program and PVsyst. According to the results, the Photovoltaic-integrated Shading systems, designed with 4 louvers with a slope angle of 45 degrees and zero degrees azimuth (facing south) has the highest efficiency compared to other scenarios and shows an energy efficiency of 35.54%, which indicates an acceptable decrease. The heating energy has been effective as well as its efficiency as a combined photovoltaic system in producing energy and controlling solar radiation simultaneously. The present study provides the required information on the parameters of Photovoltaic-integrated Shading systems and paves the way for the development of photovoltaic technology integrated with building components in the design steps.


Introduction
The photovoltaic system is one of the most promising clean energy technologies that can be a good alternative to fossil fuels that produce large amounts of greenhouse gases. Therefore, the use of photovoltaics in building design is one of the comprehensive approaches in the construction industry Building Integrated Photovoltaics and Building Applied Photovoltaics are the two main types of two solar installation integration techniques. Building Applied Photovoltaics is used to refer to the photovoltaics that is installed in the building after the construction is completed; Integrated photovoltaics, on the other hand, represent the concept of replacing conventional building envelops such as windows, walls, and ceilings with photovoltaics [1]. Photovoltaic systems that are nowadays installed in existing building envelopes are known as building-integrated photovoltaics. Among these systems, include multifunctional elements, that also role as shading and are called Photovoltaic-integrated Shading systems that can reduce the internal heat gain and lighting needs and Operate as a power generator to achieve zero energy buildings [2]. Therefore, integrated photovoltaic systems, both as part of the building envelope and as an on-site power generator, can simultaneously reduce the use of fossil fuels and greenhouse gas emissions [3]. During the last century, the ratio of transparent envelop in office buildings has increased significantly [4]. Therefore, the use of shadings systems, as a protection against the sun, can help the overall energy balance of these systems and as a cost-effective and aesthetically acceptable device, as well as integrate a renewable system in the building [5]. Based on the cases and literature review, it seems that the use of this type of photovoltaic system according to the design area, ie hot arid climate can play an effective role in reducing the annual energy consumption of the building; Because of the working hours of office buildings, which are mainly used during the day and at the same time with effective sunlight, we can expect good performance for photovoltaic systems. Therefore, choosing the optimal type of shading and its proper integration with photovoltaics can provide a high amount of energy efficiency in such buildings.
The goal of this research is to evaluate and compare different types of Photovoltaic-integrated Shading systems and their effect on optimizing energy performance in an office building with a conventional structure in Shiraz as an example for such buildings.
Therefore, the following questions regarding the use of solar energy in office buildings are before researchers: To what extent will the Photovoltaic-integrated Shading systems design be effective in improving the cooling and heating performance of the Shiraz office building? Which types of photovoltaic arrangement integrated with the shading system designed will have the best energy performance in the office building in Shiraz?

Material and Method
The goal of this study is to determine the criteria and characteristics of Photovoltaic-integrated Shading systems; In this regard, by studying library resources and valid standards, the required data were collected and then by modeling in Design Builder software that allows simulation of architectural spaces taking into account climatic characteristics, the thermal performance of the model was made and Was tested. This software uses the Energy Plus modeling engine, which has been validated by Oak Rigg National Laboratory according to quality laboratory measurements [6]. According to the climatic data of Shiraz and based on the proper orientation of buildings in this climate, the dimensions of the spaces, the type of envelopes, the type of openings and their direction, and the amount of activity of users as fixed components in this study are assumed. According to the start and end hours of the office buildings activity, the time of activity was considered between 7 in the morning and 4 in the afternoon. Also, according to the type of selected space, the level of occupation by individuals based on 0.33 per square meter was considered and the facilities and tools used in an office space were defined. The type of materials for the outer envelope of the building was determined based on the optimal thermal conductivity. Also, the variety of designed shades system according to the type, dimensions, size, and angle of installation was determined separately and the specifications related to each type of shade were determined.
In the next step, the amount of cooling and heating energy required for the sample was calculated according to the specifications of each sample. Then, in PVsyst software, according to the surface, angle, and type of shadings, photovoltaic panels were considered to be placed on the surface of the shadings for 15 studied samples, and finally, the energy production of these integrated panels was estimated according to the type of shading. This software works in a completely comprehensive and practical way in the field of working with photovoltaic systems, which includes a set of necessary tools for studying and researching and sizing, simulating, and analyzing data of photovoltaic systems. This software is continuously updated and is one of the best and most widely used software in the field of the design of photovoltaic systems [7].

Radiation information related to the city of Shiraz.
Determining the photovoltaic performance in a climate is one of the most important factors in determining the amount of radiant energy in that area, the average annual radiation of Shiraz is equal to 2424 kWh per square meter per year [8].

Simulation process
To perform the simulation in Design Builder software, first Shiraz weather file in TMY format, which includes complete weather characteristics including exact latitude and longitude, monthly temperature, and other climatic characteristics, was entered into the software, then office space with Dimensions of 3 × 3 meters as the minimum standard of office space [9], and height of 3 meters and the specifications of windows with dimensions of 150 × 150 cm, which is 120 cm from the floor, all following the design of office spaces mentioned in the national regulations of office buildings It was designed on the south facade (the favorable front for receiving solar energy in this climate) with different shading types. Due to the latitude of Shiraz, the study of the vertical shadings system and also, two samples of horizontal shadings system were simulated and considered for comparison and selection of the best possible option. Other design specifications of the building in the Builder Design software environment were adjusted according to the definition of an office room, including the use of conventional electrical appliances, cooling and heating systems by working hours, and the number of users stationed. Also, according to the most desirable heat exchange coefficient, (suggested by the software itself), materials, wall coverings, and ceilings were determined. The total amount of energy required by the samples according to each type of shading system will be obtained as the first output of the Design builder so that the effect of the type of shading system on the total energy will be determined.
According to the shading system designed for each sample in the next step, using PVsyst software, the photovoltaic panel was considered by the shading system designed. Initially, the angle of the panels was determined according to the angle, number, and length intended for each type of shading system, and the direction of the building in all options was considered to be south. Specifications of the type of panels designed for the 15 specimens conforming to the perfectly matched shading system were taken into consideration. Determining the characteristics of the modules is the next step of the research, which is presented in Table 1.

Table1. Specifications of selected photovoltaic modules
for each sample.
Then, in the next step, the amount of energy produced by the photovoltaic panel is calculated for each designed sample, and the amount of radiant energy is determined in terms of each sample.
Based on the analysis of the results, the studied samples 12 and 8 with the angle of inclination of the panel at zero degrees and 45 degrees, showed the highest energy production with values equal to 803.9 and 725.9 kWh per year, respectively.
On the other hand, sample 9 Photovoltaic-integrated Shading systems showed the lowest amount of energy production with a value equivalent to 201 kWh per year. Since the studied samples 12 and 8 compared to other samples show better performance in terms of energy production according to the type of design, so the next step is to evaluate and measure the performance of photovoltaics in the direction of deviation to the southeast and southwest was addressed. The angles of the variable azimuths were examined.
According to the obtained results, the amount of change in the amount of energy produced by the Photovoltaic-integrated Shading systems by changing the degree of azimuth to the southeast and southwest was investigated to determine the effect on the energy output of the system.
In sample 12, the change of azimuth did not change the performance of the system, but in sample 8, due to the initial energy production of 725.8 kWh per year, this figure showed an increase in performance by changing the direction of rotation to the southwest, the highest value at an angle of 20 Indicates a degree to the southwest of 729.5; Also, the further deviation is not directly related to performance improvement and we see a decrease in system performance at a -30 degree angle. According to the amount of energy required for the building and the energy produced by Photovoltaicintegrated and according to 1 Equation, the efficiency of the system can be obtained. Yield estimates for all samples are presented in Figure 1.   window surface, energy efficiency has increased with increasing blade angle and number and increasing the surface area of the panels. Sample 12, Photovoltaicintegrated horizontal shading systems with a width of 2 meters, shows the second rank of the best efficiency among the samples. This indicates that despite the shading of the blades on the window surface, energy efficiency has increased with increasing blade angle and the number and size of panel surfaces. Sample 12, Photovoltaic-integrated horizontal shading systems with a width of 2 meters, shows the second rank of the best efficiency among the samples.

Conclusions
Shading systems cure building energy performance and user comfort by controlling glare, natural light, and solar gain. On the other hand, the Photovoltaicintegrated Shading systems build new opportunities for integrated photovoltaics with the building; the performance of these systems in different conditions of integration is very different from the building. According to the simulation performed in the research, based on the climate and geographical location of Shiraz, the integrated photovoltaic system with a horizontal canopy shows good performance; As the photovoltaic system integrated with the horizontal canopy (Louvre) showed 35.54% energy efficiency, which indicates the efficiency and effectiveness of this system in reducing heating energy and energy production and controlling daylight simultaneously. Furthermore, the results showed that by applying a change in the azimuth of the system by 20 degrees to the southwest, we will see a 35.73% reduction in energy consumption. Therefore, considering the potential of such systems, they can be used as an efficient solution that in addition to providing thermal comfort to prevent radiation, provide part of the building energy. As it was found from the results of this study, the integration of the shading system with photovoltaics in addition to reducing the annual energy demand of the building through energy production improves the overall energy performance of the building and will play an important role in reducing energy consumption and to providing thermal comfort. In the context of future research proposals, a wider variety of shading systems in other building orientations can be compared and evaluated. Also, the development of studies for other highconsumption buildings such as commercial and residential buildings and in other climatic areas of the country can be considered in future research. [1]

Abstract
Photovoltaic-integrated Shading systems, are multifunctional components to generate electricity and simultaneously provide the shade needed for building surfaces and walls. Applying integrated photovoltaic systems with building components, including fixed shadings, in addition to regulating the penetration of sunlight and saving energy, seems to be a fully functional approach due to the production of part of the buildings' energy. Therefore, to evaluate the performance of Photovoltaic-integrated Shading systems, in optimizing energy consumption, the need to study the effect of Photovoltaic-integrated Shading systems, on energy in Shiraz was considered. Therefore, 15 Photovoltaicintegrated Shading systems scenarios for the facade of an office space model were calculated using the DesignBuilder simulation program and PVsyst. According to the results, the Photovoltaic-integrated Shading systems, designed with 4 louvers with a slope angle of 45 degrees and zero degrees azimuth (facing south) has the highest efficiency compared to other scenarios and shows an energy efficiency of 35.54%, which indicates an acceptable decrease. The heating energy has been effective as well as its efficiency as a combined photovoltaic system in producing energy and controlling solar