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Article

A Rooftop Solar Photovoltaic Tree Solution for Small-Scale Industries

by
Sumit Chowdhury
1,
Maharishi Vyas
1,
Abhishek Verma
1,2,* and
Vinod K. Jain
1,2
1
Amity Institute of Renewable and Alternate Energy, Amity University Uttar Pradesh, Sector 125, Noida 201313, Uttar Pradesh, India
2
Amity Institute for Advanced Research and Studies (Materials and Devices), Amity University Uttar Pradesh, Sector 125, Noida 201313, Uttar Pradesh, India
*
Author to whom correspondence should be addressed.
Sustainability 2024, 16(22), 9901; https://doi.org/10.3390/su16229901
Submission received: 27 August 2024 / Revised: 6 November 2024 / Accepted: 7 November 2024 / Published: 13 November 2024
(This article belongs to the Section Energy Sustainability)
Browse Figures
Figure 1
<p>Schematic diagram of (<b>a</b>) an SPVT and (<b>b</b>) a conventional SPV system (ground-mounted).</p> "> Figure 2
<p>Design of a conventional rooftop solar system.</p> "> Figure 3
<p>Design of rooftop solar photovoltaic tree (Marigold type). (<b>a</b>) Top view and (<b>b</b>) side view.</p> "> Figure 4
<p>Comparison analysis of conventional rooftop SPVs with SPVT systems.</p> ">
Versions Notes

Abstract

:
With the increase in population and the growing demands of industrialization, carbon emissions across the globe are increasing exponentially. Furthermore, the demand for clean energy from renewable sources (solar, wind, etc.) is growing at an unparalleled rate to fight against the climate change caused by these increased carbon emissions. However, at present, it is very difficult for small-scale industries in urban areas to install solar power systems due to constraints around the operation area and on rooftops. Therefore, these small-scale industries are not able to install any solar plants and, thus, are not able to reduce their carbon emissions. In the context of this problem regarding the generation of cleaner energy and reducing carbon emissions by small-scale industries in urban areas, a model of a rooftop solar photovoltaic tree (SPVT) has been proposed that may be considered by small-scale industries in the place of a conventional rooftop solar photovoltaic (SPV) system. It is also noted that various models of SPVT systems are commercially available on the market, each with their own unique features. However, no new SPVT model has been designed or provided in this paper, which simply presents simulation studies comparing a conventional rooftop SPV system and an SPVT system. The results show that a 9.12 kWp SPVT system can be installed in just 6 Sq.mt, while a 3.8 kWp conventional SPV system requires 40 Sq.mt of rooftop area. Consequently, an SPVT generates around 128% more electricity than a conventional SPV, leading to greater reductions in carbon emissions. Thus, the objective of this study is to identify the most suitable option for small-scale industries in densely populated urban areas to generate electricity and maximize carbon emission reduction.

1. Introduction

Energy is the ultimate requirement for the existence of human life and industrialization. Thus, energy generation through various sources, including conventional sources, i.e., fossil fuels, and non-conventional sources, including solar, biomass, and wind, is a critical and important aspect of life. However, due to the rise in the human population and commercialization, the demand for energy has increased significantly, leading to a heavy reliance on conventional energy sources. However, there is an urgent need to transition to renewable energy sources to protect the environment; support a low-carbon future; and ensure affordable, reliable, and modern energy services. This shift aligns with the United Nations’ Sustainable Development Goal (SDG) 7: Affordable and Clean Energy. At present, renewable energy comprises around 30% of the global power mix as of 2023, which is expected to grow to 35% by 2025 [1]. Around one-sixth of the world’s primary energy sources come from renewable energy [2]. Similarly, in India, the share of renewable energy in total energy production reached around 19.5% in 2023, which is an increase from 15.2% in 2010 [3]. At COP26, India made an ambitious plan to become net zero by 2070 [4]. In this regard, small- and medium-level companies in India are uninformed and unaware of how to assess their carbon footprint and, thus, how to offset their carbon emissions through the adoption of renewable energy/SPV systems. Furthermore, other major problems faced by small- and medium-scale industries are either due to a shortage of funds for adopting renewable energy or a lack of area for the installation of solar photovoltaics (SPVs). Therefore, in this paper, the authors have tried to provide a streamlined solution for the generation of power with a small area of availability by providing a new design of SPV, i.e., solar photovoltaic trees (SPVTs), in comparison with the conventional SPV system, thus offsetting a large amount of carbon emissions.
SPVTs are a non-conventional solar photovoltaic system that counterfeits the appearance of a real tree [5] and has a high power-to-land occupancy ratio. They have a sophisticated and unique design that consists of multiple solar photovoltaic modules, battery banks for storage, a charge controller, and inverter circuitry to supply electrical loads. SPVTs may be slightly costlier than conventional SPV systems due to the requirement of more expensive installation materials, especially the steel structure [6]; however, they have the advantage of generating more power with a lower occupancy area, and the space between the SPVT’s modules and base surface can be further utilized as a storage area or for gardening.
At present, various models and designs of SPVTs are available on the market. Multiple studies have been conducted on SPVTs, with some focusing on the land-to-power ratio, efficiency, the fabrication process, costing, etc. SPVTs have the advantage of generating more power with a lower land requirement, as they capture more sunlight than a conventional SPV [7]. Deep et al. [8] have suggested that by using the Spiralling Phyllataxy technique, the efficiency of the SPVT can be improved. SPV modules placed in a Fibonacci series on an SPVT generate 50% more energy than modules arranged in an array. An SPVT-based water pump was designed and developed for agriculture usage in India. The costs of this standalone SPVT with a battery system were analyzed, and it was found that its payback period was 10.5 years [9]. The first solar tree with square leaves was installed in Nevere, France, in 2017, which allows passers-by to charge their phones and surf the internet. This tree was inspired by acacia trees, which are found in the Israeli desert and African savanna [10]. A research study conducted by Farhan H. et al. [11] found that the annual generation of electricity from an SPVT was 17.79%, 41.06%, and 20.97% more than conventional SPVs of the same capacity installed in Kuala Lumpur, Bhopal, and Barcelona, respectively. Furthermore, a new study on the applications of SPVTs was conducted by Marwa I. et al. [12]. In this study, an SPVT system was designed to power up the lighting at the Grand Egyptian Museum in Egypt, as well as mobile and laptop devices in public urban areas. This study also suggested that the payback period of the solar tree would be 10 years, and it would save around 11,240 tons of CO2 emissions throughout the system’s lifetime. M. Vyas et al. [13] have proposed four different ground-mounted SPVTs, named Tulip, Sunflower, Marigold, and Daisy. Moreover, Dey et al. [14] discussed the site-specific higher electrical output when using minimal structural materials. Energy optimization was achieved by controlling the shadow losses after adjusting the PV modules to different tilt angles.
The above research primarily focuses on various design aspects, power generation, and the payback period of SPVT systems. However, none of them address installation on commercial buildings or organizational rooftops, where space availability is a constraint. In India, most cities in urban areas are highly congested due to population growth, making space availability limited. Herein, the prime focus is to outline rooftop SPVTs and compare their output with conventional rooftop SPV systems with respect to the availability of rooftop area. Thus, in this research article, a conventional rooftop SPV system and rooftop SVPT designs are simulated, analyzed, and studied, and considerations are made in relation to how these designs have helped in reducing the carbon footprint of an industry where the area for SPV installation is a constraint.
Considering the same research work, simulation studies of proposed SPV systems are presented in Section 2. Furthermore, the analysis, findings, and comparison with respect to various parameters, such as electrical specifications, system cost, payback period, and carbon emissions reduction comparison, are discussed in Section 3. The outcomes and conclusions drawn from the present research work are presented in Section 4.

2. Simulation Study of Rooftop SPVs

In the simulation study, the authors carried out a comparative analysis of SPVTs, specifically the Marigold-type tree and a conventional-type SPV system on a rooftop. In this paper, the authors selected the Marigold-type SPVT, as it has a higher power-to-land ratio than the Tulip- and Sunflower-type SPVTs. Furthermore, it is easier to install and maintain compared to other designs like the Daisy SPVT [13]. This analysis helps to determine what type of rooftop SPV system may be installed in a spatially constrained area. Herein, the research analyses the rooftop of M/s RECW (Ravi Engineering and Chemical Works), which is located in Bawana in Delhi, India (28°78′ N, 77°06″ E), and has a total available rooftop space of 52 Sq.mt. Two different designs of a SPV rooftop system were identified using SketchUp Pro Desktop 2021.0 software. Furthermore, PVSyst software (version 7) was used to analyze the total energy yield of the proposed conventional SPV system and Marigold SPVT on the rooftop. The basic difference between the SPVT and conventional SPV system is the aesthetic design; i.e., the placement of the solar modules and the elevated structure of the PV system and all other components such as the inverter and AC/DC cables, will remain the same (Figure 1a represents the basic SPVT and Figure 1b represents the conventional SPV system design). This tree-type structure is used to enhance the overall surface area to capture solar energy and to convert it into electricity more efficiently in low-light settings and where area is constrained [15].
In Figure 1a, it is clearly shown that the solar panels are attached to a single pole-like structure, which is further attached to a small base. However, in a conventional rooftop or ground-mounted solar photovoltaic system, all the solar panels are attached to multiple solid structures, as shown in Figure 1b, which covers a larger area [16].

2.1. Simulation Design of Conventional Rooftop Solar Photovoltaic Systems

A model of a conventional rooftop SPV system was designed to carry out a comparative analysis with a rooftop SPVT—a Marigold-type system. In this conventional rooftop SPV system, the panels are connected in series and are installed on a rooftop using concrete foundation blocks, as shown in Figure 2. For conventional rooftop SPV systems, the same type of panels that are used for SPVT modelling were considered; i.e., 10 monocrystalline-type (72 cells) solar modules with 380 Wp capacity each (at STC) are connected in series. Thus, the total DC capacity of the rooftop SPV system is 3.8 kWp at STC. Here, the modules are placed at a 20-degree tilt angle, and the overall structure is installed at a 45-degree azimuth angle based on the location of the installation, with a standard rooftop floor clearance of 0.5 mt. The total area covered by the conventional rooftop SPV system is ~40 Sq.mt (76.92% of the total available rooftop area). Furthermore, in order to connect the DC system with the AC load, a 4 kW capacity inverted is connected to the system. The overall system has a specific yield of 1479 kWh/kWp/year (as simulated on PVSyst software) with an annual production (P50) of 5619 kWh.

2.2. Simulation Design of Rooftop Solar Photovoltaic Tree—Marigold Type

Marigold-type SPVT structures are identical to a marigold flower [13]. Marigold flowers have various outward-type petals arranged in close proximity; in the same way, the solar panels are arranged in close proximity and are attached to a steel structure, which is further mounted to the floor of the rooftop using concrete blocks, as shown in Figure 3. This design will further ensure adequate ventilation within the operation area of the industry.
For the simulation study, a Marigold-type SPVT was considered, which has 24 monocrystalline-type (72 cells) solar panels with 380 Wp capacity each (at STC). Thus, the total DC capacity of the SPVT is 9.12 kWp at STC. The SPVT consists of eight branches and each branch has three modules, which are placed at a 20 degree tilt angle; additionally, the overall structure is installed at a 45 degree azimuth angle based on the location of the installation. No shading was caused by the height of the nearby building, other than from the boundary wall of the rooftop, which is 0.6 m high. The ground clearance of the structure (from the lowest edge of the SPV module to the floor of the rooftop) is taken to be approximately 1.0 m. The overall height of the steel pole where all the modules are attached is no more than 1.8 m. The total rooftop area engaged by the structure is around ~6 Sq.mt, which is only 11.53% of the total available rooftop area. To accommodate the structure, a 10 kW inverter is connected to the structure to form a complete AC system. Furthermore, it was found that the specific yield of the rooftop SPVT model was 1408 kWh/kWp/Year (as simulated on PVSyst software) with an annual production (P50) of 12837 kWh.

3. Results and Discussion

The design simulation of two rooftop solar systems—namely, the conventional rooftop SPV system and the Marigold-type SPVT system—was conducted to determine the superior system in terms of solar area requirement and energy generation for a limited rooftop space. This will help small-scale industries select the type of solar rooftop system to be installed for a specific location, further helping to reduce the overall carbon footprint of the industry. To carry out the comparative study of the two different rooftop SPV systems, a few aspects were considered to be the same, i.e., the type of solar module (72 monocrystalline-type cells), the capacity of each module (380 Wp), and the tilt and azimuth angles (20° and 45°, respectively) based on the specific location. Through simulation analysis, it was observed that the rooftop Marigold-type SPVT with a 9.12 kWp capacity will produce 12837 kWh annually (P50-STC), with a specific yield of 1408 kWh/kWp/year. However, conventional rooftop SPV systems with a capacity of 3.8 kWp will produce 5619 kWh (P50-STC), with a specific yield of 1479 kWh/kWp/year. The comparative specifications and electrical analysis of both systems are provided in Table 1.

3.1. Area Covered

Based on the simulation analysis, it was outlined that the conventional rooftop SPV system occupied more space in terms of installation, as it is horizontally spread across the roof’s available area. However, the Marigold-type rooftop SPVT system was installed vertically using a steel pole, and its branches hold the solar modules. Thus, the area required for its installation is much smaller than the conventional rooftop SPV system. The overall area occupied in terms of installation by the conventional system is ~40 Sq.mt, whereas the area occupied by the rooftop SPVT is ~6 Sq.mt, which is around 85% less than the conventional system. Moreover, when a typical SPV is built on a rooftop, access to the available space on the roof becomes obstructed. However, in the case of an SPVT, this discomfort is insignificant. The space beneath a rooftop SPVT can easily be converted for other purposes, such as storage and gardening.

3.2. Energy and Carbon Reduction

After analyzing the energy and carbon reduction capacity of both types of SPV, it was observed that the installed capacity of the rooftop SPVT is much higher than the installed capacity of the conventional rooftop SPV system due its structural advantages over a constrained or limited area of available rooftop. The SPVT with a capacity of 9.12 kWp installed over a rooftop can generate about 12,837 units annually. Similarly, on the same rooftop, a conventional rooftop SPV system with a capacity of 3.8 kWp can be installed and, thus, will be able to generate only 5619 units annually. Therefore, the Marigold-type SPVT will produce around 46.21 GJ and will subsequently be responsible for a 10.53 tCO2 carbon reduction over a year. Similarly, the conventional rooftop SPV system will produce around 20.23 GJ and will be responsible for a 4.6 tCO2 carbon reduction annually. The above values of energy [17] and carbon reduction [18] are calculated based on Equations (1) and (2):
Energy in Giga Joules (GJ) = x × 0.0036
Carbon Emissions Reduction (tCO2) = x × 0.82 × 103
where x = electrical units generated from the source in kWh; ‘0.0036’ is the conversion factor of kWh to GJ; and ‘0.82’ is the average grid emission factor in India, as per the Central Electricity Authority of India [19]. The formula for calculating carbon emissions from electricity usage is as follows: CO2 emissions (kg) = Electricity consumption (kWh) × Carbon intensity (kgCO2/kWh). By using this formula, one can determine the reduction in carbon emissions when solar energy is used, considering that the usage of solar energy will replace or reduce the consumption of grid or conventional electricity.
Based on the above, it is evident that the simulated Marigold-type rooftop SPVT will be able to produce a significant reduction, i.e., 56% more carbon emissions than the simulated conventional rooftop SPV system.

3.3. Cost of the System

The cost of an SPV system varies based on the type and make of the various components of the system. However, an SPVT is more expensive than a conventional roof-mounted SPV system due to its structural design [20]. A typical 5 kWp grid-connected SPVT costs around 5457 USD in India [21]. Thus, the cost for a 9.12 kWp rooftop SPVT will be around 9954 USD; however, the cost per watt is just 0.92 USD/W. Similarly, the benchmark cost of a grid-connected rooftop SPV system for 3 kW up to 10 kW is 542 USD per kW [22]. Therefore, the overall cost of a 3.8 kWp grid-connected conventional rooftop SPV system is 2060 USD and the cost/watt is 1.84 USD/W. This shows that the overall cost of an SPVT is higher than that of a conventional rooftop SPV system; however, the cost per watt is much smaller in the case of SPVTs. Furthermore, the above cost includes the solar modules; inverter; mounting structure; balance of the system, e.g., cables, switches, circuit breaker, connectors, junction box, mounting structure, earthing, lightening arrester, and civil works; installation and commissioning; maintenance contract for 5 years; transportation; insurance; applicable taxes, etc. Additionally, the above-mentioned costs do not include the cost of land, net metering cost and subsidy, or central financial assistance provided by local government on the rooftop solar system, which is in the range of 20 to 40% [23].

3.4. Payback Period of Rooftop SPVTs

When assessing the feasibility of a project, the consideration of the payback period is deemed crucial. Therefore, it is important to identify the payback period of both the conventional rooftop SPV system and the Marigold-type SPVT. Based on our simulation analysis, a rooftop SPVT with a capacity of 9.12 kWp can produce around 12,837 kWh or units in a year. In Delhi, India, the electricity cost per unit is around 0.17 USD for commercial use [24]. The small-scale industry that we have considered in our study, i.e., M/s RECW in Delhi, India, uses around 7756 units per year. Thus, the amount of money that this company can save is around 7756 × 0.17 USD = 1318.5 USD, if it installs a rooftop SPVT. Furthermore, M/s RECW can earn on the excessive units generated. Thus, the cost of the remaining units, i.e., 12,837 − 7756 = 5081 units, is around 308 USD, considering that the surplus solar output cost is 0.06 USD per unit [25]. For the above calculation, a conversion factor of 0.01 for INR to USD is used [26]. Therefore, in a year, M/s RECW can save up to 1626.5 USD. Therefore, the overall rooftop SPVT system will be free within 9954/1626.5 = 6.12 years, considering no change in electricity cost. Similarly, a 3.8 kWp conventional rooftop SPV will generate 5619 kWh or units in a year, which saves around 955.23 USD, considering commercial electricity costs are around 0.17 USD per unit. Also, the company needs to pay for the remaining units, i.e., 7756 − 5619 = 2137 units, which will be around 2137 × 0.17 USD = 363.29 USD in a year. Thus, the net cost savings will be around 955.23 − 363.29 = 591.94 USD. Therefore, the payback period for the conventional rooftop SPV will be around 2060/591.94 = 3.48 years. The above calculations for both the rooftop SPVT and the conventional rooftop SPV system were carried out with certain assumptions, i.e., no change in electricity cost for the next seven years and with no degradation loss of the solar modules.

3.5. Advantages Associated with Rooftop SPVTs

Rooftop SPVTs are more efficient in terms of energy production in comparison to any conventional rooftop SPV system because of their unique design and their capability of consisting of multiple solar panels [27]. Apart from this advantage, there are other advantages associated with rooftop SPVTs, which are mentioned in Table 2.
The overall stimulation study is a comparison of the conventional rooftop SPV system and the Marigold-type rooftop SPVT for a specific location with a rooftop area of 52 Sq.mt., as summarized in Table 3 and Figure 4. Based on the comparison above, it has been observed that the Marigold-type rooftop SPVT requires 85% less area for installation compared to a conventional rooftop SPV system. The proposed Marigold-type rooftop SPVT requires 93.8% less area compared to a conventional rooftop SPV system for installing a 1 kWp system. These results converged with the findings of M. Almadhhachi et al. [28], who indicated that only 0.01 Sq.mt of land is needed to install a Sunflower-type solar tree with a 32.4 Wp capacity, representing a 96% reduction in area compared to the conventional flat PV system. Similarly, M. Vyas et al. [13] corroborated this by stating that a Marigold-type solar tree model requires 1.01 Sq.mt per 1 kWp, approximately 92.3% less than the conventional ground-mounted solar plant. Likewise, a Sunflower-type solar tree requires 92% less area compared to a conventional PV system of the same capacity. Additionally, the designed rooftop SPVT generates approximately 128% more electricity units as compared to a conventional rooftop SPV system, which is the primary advantage of its installation. Consequently, it boasts a 50% lower cost per watt (USD/W) value and offers around 129% higher carbon reduction potential per year as compared to conventional rooftop SPV systems. However, when considering the overall system cost, a rooftop SPVT entails a longer payback period, approximately 76% higher than conventional rooftop SPV systems, which should be acceptable considering the life span of a solar power plant.
SPVTs may be used in various fields and for multiple applications, particularly in small-scale industries. A few examples have been listed below:
(a)
Community Water Purifier: in rural areas, SPVTs can be harnessed to supply electricity for operating community-based water purification systems.
(b)
Farming Area: the concept of SPVTs may be used in the farming sector of the country to generate more energy in smaller areas, thus reducing the impact of the overall farming area.
(c)
Rural Banks and ATMs: SPVTs may be installed at banks and ATMs in rural areas where the availability of electricity is a deep concern.
(d)
Hotels and Restaurants: SPVTs may be used in hotels or restaurants near swimming pools to cater to the electricity demand along with a good landscape view.

3.6. Limitations and Future Scope of Work

There is no doubt that SPVTs in the field of renewable energy are gaining momentum. However, there are various concerns related to SPVTs which make their acceptance and existence more difficult.
(a)
Initial Cost of Rooftop SPVT: Currently, all the available SPVTs possess a high cost of design and installation due to the requirement of a high quantity of steel in the framing structure. This should be addressed by researchers in their new design.
(b)
Policy Intervention: At present, local governments are only concerned about solar parks and commercial solar installation. There is a lack of guidance or policies related to SPVTs across the globe. Governments should work cohesively with local administrative bodies to outline standard guidance documents for SPVTs. This should include central financial assistance, the type of module used, tax rebates, etc. In India, state-specific rooftop solar policies are available for commercial buildings, but they are not widely adopted by stakeholders. In some states, the cumulative capacity of all solar systems installed in a given area must not exceed 30% of the local distribution transformer’s capacity, while in others, the limit is only 15%. If this threshold is increased to 50–60%, adoption and implementation will likely improve.
(c)
Skill Development: Designing and installing SPVTs requires specific knowledge, including that relating to the structure and technical aspects of the tree. As it is an emerging field, skill development is an essential requirement to make this field successful.
(d)
Awareness: At present, the awareness level of SPVTs is limited to researchers. The general public should be informed of this new and advanced technology. This can be achieved through promotional activities on the SPVTs. This should be introduced in the curriculum of school- and college-level studies.
Along with the above limitations, there is a tremendous scope of work that can be undertaken in the future, such as designing different rooftop SPVTs for a better efficiency and production yield. In addition, authors, along with RECW, will install the above mentioned SPVTs on the rooftop of the RECW facility and validate the data in the upcoming years. Further designing of mobile SPVTs that can move from one place to another can be promoted.

4. Conclusions

SPVTs can play a pivotal role in the field of renewable energy. They have unique features that can distinguish them from other conventional rooftop SPV systems. The main feature of SPVTs that can be an asset for any system owner is their high energy generation capacity in small areas. Other than this, SPVTs are aesthetical, which may enhance the beautification quotient of the area. Furthermore, the concept of rooftop SPVTs can be taken to a commercial level in order to beat the area requirement for the installation of solar PV systems in a congested urban area. In this paper, the authors have tried to address an important aspect of environmental protection, i.e., how small-scale industries in urban areas can meet their energy needs and reduce carbon emissions through the installation of rooftop SPVTs, where the availability of rooftop area is a challenge.
Furthermore, simulations of conventional rooftop SPV systems and rooftop SPVTs have been carried out to determine which system is better with respect to the limited availability of rooftop space. The below observations can be concluded from the research analysis:
(a)
The design simulation of two types of rooftop solar systems, i.e., a conventional rooftop solar photovoltaic system and a Marigold-type solar photovoltaic tree, based on the availability of rooftop area have been carried out on PVsyst. M/s RECW in Delhi, India, was considered for this study, which has a 52 Sq.mt rooftop area.
(b)
On the available rooftop area, a 9.12 kWp capacity Marigold-type SPVT can be installed, which will generate around 12,837 kWh energy annually, which is 128.46% higher compared to conventional rooftop SPVs. It will occupy only around 11.53% of the rooftop area. Meanwhile, a conventional rooftop SPV system with a capacity of 3.8 kWp can be installed and will be able to produce 5619 kWh energy in a year. This conventional rooftop SPV system will occupy 76.92% of the total available rooftop area. Furthermore, rooftop SPVTs require 85% less area compared to conventional SPV systems.
(c)
As estimated, Marigold-type SPVTs with a capacity of 9.12 kWp will produce around 46.21 GJ of energy in a year and will subsequently be responsible for a 10.53 tCO2 carbon emissions reduction over a year, which is 128.91% higher compared to conventional rooftop SPVs. Similarly, the 3.8 kWp conventional rooftop SPV system will produce around 20.23 GJ and will be responsible for a 4.6 tCO2 carbon emission reduction annually.
Therefore, based on the above conclusions, it is evident that the suggested Marigold-type SPVT system can provide better sustainable solutions than conventional rooftop SPV systems for small-scale industries in urban areas. This new idea of using SPVT structures in urban areas comes with certain limitations such as the high capital costs of the structure and a prerequisite that the rooftop should have an adequate load bearing capacity in a small coverage area, as the entire weight of the SPVT structure is on a single foundation pole. Future areas of development can be focused on techno-commercial weight and structure optimization so that the SPVT can be easily available to small-scale industrial customers. Compared to other prevalent technologies like solar roofing tiles, the SPVT is more robust and economical as it is widely available, whereas solar roofing tiles technology is not widely used in the market and is expensive in comparison.

Author Contributions

Conceptualization, investigation, simulation, and writing—original draft: S.C.; software and simulation support and analysis: M.V. and A.V.; visualization and review and editing: A.V. and V.K.J.; project administration: A.V.; supervision: V.K.J. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data provided in this article are available upon request from the corresponding author. The data are not publicly available due to privacy reasons.

Acknowledgments

The authors are thankful to Ashok K. Chauhan, Founder President, Amity University, for his continuous encouragement and support. Sumit Chowdhury, one of the authors, would like to express their gratitude to Praveen Saxena, Skill Council for Green Jobs, New Delhi, India, for his guidance on the renewable energy sector. Additionally, Sumit Chowdhury extends his thanks to R Babu and Sourav Dey, Ravi Engineering & Chemical Works (RECW), New Delhi, for allowing the authors to visit their facility and for granting permission to carry out the simulation of conventional rooftop SPVs and rooftop SPVTs on their premises, as well as assuring the authors that they will install the said SPVT on the rooftop of their facility in the near future.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Schematic diagram of (a) an SPVT and (b) a conventional SPV system (ground-mounted).
Figure 1. Schematic diagram of (a) an SPVT and (b) a conventional SPV system (ground-mounted).
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Figure 2. Design of a conventional rooftop solar system.
Figure 2. Design of a conventional rooftop solar system.
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Figure 3. Design of rooftop solar photovoltaic tree (Marigold type). (a) Top view and (b) side view.
Figure 3. Design of rooftop solar photovoltaic tree (Marigold type). (a) Top view and (b) side view.
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Figure 4. Comparison analysis of conventional rooftop SPVs with SPVT systems.
Figure 4. Comparison analysis of conventional rooftop SPVs with SPVT systems.
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Table 1. Electrical comparison of a conventional rooftop SPV system and a Marigold-type rooftop SPVT.
Table 1. Electrical comparison of a conventional rooftop SPV system and a Marigold-type rooftop SPVT.
ParameterConventional Rooftop SPV SystemMarigold-Type Rooftop SPVT
Available Rooftop Area (Sq.mt)5252
Type of ModulesMonocrystallineMonocrystalline
Rating of Modules (Wp)380380
No. of Modules1024
Inverter Rating (KW)410
Total DC Capacity (kWp)3.89.12
Tilt/Azimuth Angle 20°/45°20°/45°
Specific Yield (kWh/kWp/Year)14791408
Annual Production (P50) (kWh)561912,837
Table 2. Advantages associated with rooftop solar photovoltaic trees.
Table 2. Advantages associated with rooftop solar photovoltaic trees.
Advantages of Rooftop Solar Photovoltaic Trees
1.
Capable of generating more energy as compared to conventional systems.
2.
Area required to install a rooftop SPVT is smaller as compared to conventional systems.
3.
A high land-to-power ratio.
4.
PV modules are mounted with higher ground/floor clearance.
5.
Suitable for small-scale industries where space availability for the installation of solar systems is very limited.
6.
Overall structure is visually appealing.
Table 3. Overall comparisons of conventional rooftop SPV systems and Marigold-type rooftop SPVTs.
Table 3. Overall comparisons of conventional rooftop SPV systems and Marigold-type rooftop SPVTs.
AspectConventional Rooftop Solar SystemMarigold-Type Rooftop Solar Tree
LocationM/s RECW, Bawana, Delhi, India (28°78′ N, 77°06′′ E)M/s RECW, Bawana, Delhi, India (28°78′ N, 77°06′′ E)
Rooftop Area (Sq.mt)5252
Software Used for SimulationPVSyst software (version 7)PVSyst software (version 7)
Total DC Capacity (kWp)3.89.12
Specific Yield (kWh/kWp/Year)14791408
Annual Production (P50) (kWh)561912,837
Ground/Floor Clearance (m)0.51.0
Ratio of Land Occupied with Available Rooftop Space (%)76.9211.53
Area Required to Set Up the System (Sq.mt)~40~6
Carbon Reduction in a Year (tCO2)4.610.53
Cost of System20609954
Cost per watt (USD/W)1.840.92
Payback Period (in Years)3.486.12
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MDPI and ACS Style

Chowdhury, S.; Vyas, M.; Verma, A.; Jain, V.K. A Rooftop Solar Photovoltaic Tree Solution for Small-Scale Industries. Sustainability 2024, 16, 9901. https://doi.org/10.3390/su16229901

AMA Style

Chowdhury S, Vyas M, Verma A, Jain VK. A Rooftop Solar Photovoltaic Tree Solution for Small-Scale Industries. Sustainability. 2024; 16(22):9901. https://doi.org/10.3390/su16229901

Chicago/Turabian Style

Chowdhury, Sumit, Maharishi Vyas, Abhishek Verma, and Vinod K. Jain. 2024. "A Rooftop Solar Photovoltaic Tree Solution for Small-Scale Industries" Sustainability 16, no. 22: 9901. https://doi.org/10.3390/su16229901

APA Style

Chowdhury, S., Vyas, M., Verma, A., & Jain, V. K. (2024). A Rooftop Solar Photovoltaic Tree Solution for Small-Scale Industries. Sustainability, 16(22), 9901. https://doi.org/10.3390/su16229901

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