Rooftop Solar Photovoltaic Systems Research Articles

Unveiling mega-prosumers for sustainable electricity generation in a developing country with techno-economic and emission analysis

In response to the urgent climate crisis, there is a growing emphasis on reducing carbon emissions and decreasing reliance on fossil fuels. This research aims to explore the possibility of enhancing renewable energy production in Bangladesh by installing photovoltaic (PV) systems on the rooftops of 30 universities to fulfill the sustainable development goal-7 (SDG-7). Helioscope is used for planning the deployment of PV systems while DIgSILENT PowerFactory is utilized for analyzing their impact on the grid. Site selection and data collection are conducted considering energy consumption and solar potential at different universities in Bangladesh. The results indicate that 29.5 MW (approximately) of power could be generated from approximately 84,295 solar panels rated at 350 W, producing about 43 GWh of electricity annually. Technical assessments on grid stability demonstrate that PV integration significantly reduces grid dependency and enhances voltage security. Economic analyses reveal that the proposed PV project is cost-effective compared to existing power plants, considering all relevant expenses. Furthermore, there is a reduction in CO2 emissions due to this project of 890.72 tons, per year, which translates to an emission factor of approximately 0.608 kg of CO2-eq/kWh. In particular, this study endorses the use of rooftop solar PV systems for universities in Bangladesh as mega-prosumers to promote sustainability and increase energy consumption, demonstrating their technical, economic, and environmental feasibility.

Climate Change Implications for Optimal Sizing of Residential Rooftop Solar Photovoltaic Systems in Qatar

Climate change poses critical challenges for Qatar’s energy-intensive residential building sector. This study evaluates the impact of projected climate warming on optimizing rooftop solar photovoltaics (PV) for villas. An integrated modelling approach is employed, combining building energy simulation, PV system optimization, and performance assessment under varying climate scenarios. A typical Qatari villa is modelled in DesignBuilder and simulated under the baseline (2002) conditions and the projected years 2016, 2050, and 2100, reflecting incremental warming. Results show the villa’s annual electricity consumption will grow 22% by 2100, with summer peaks escalating to 26% driven by surging cooling demands. Techno-economic optimization in HOMER Pro (version 3.10) verifies a grid-connected rooftop PV system as optimal in all years, with capacity expanding from 7.4 kW to 8.2 kW between 2002 and 2100 to meet rising air conditioning loads. However, as temperatures increase, PV’s energy contribution declines slightly from 18% to 16% due to climate change degrading solar yields. Nonetheless, the modelled PV system maintains strong financial viability, achieving 5–8 years of paybacks across scenarios. This analysis provides empirical evidence of distributed PV’s effectiveness for Qatar’s households amidst escalating cooling consumption. However, maintaining solar mitigation potential requires evolving PV sizing methodologies and incentives to account for declining panel productivity at the country’s peak temperatures exceeding 50 °C. Overall, this study’s integrated framework evaluates residential solar PV systems’ capabilities and appropriate policy evolution under projected climate impacts for the first time in Qatar. The modelling approach and conclusions can inform building codes and pro-solar policies to accelerate adoption for emissions reduction. With villas representing over 100,000 units in Qatar, widespread rooftop PV integration can meaningfully contribute to national sustainability targets if implementation barriers are addressed considering climate change effects.

A framework for evaluating urban solar adoption considering economic and environmental priorities of project owners

In recent years, the utilization of photovoltaic (PV) solar systems in built-up regions have received more attention due to global warming issues and the need to mitigate the dependence on fossil fuels in buildings. In this context, it becomes critical to comprehend the economic and environmental implications of roof-installed PV systems for project owners looking to expand their usage. Thus, there is a need to develop a framework for optimizing rooftop solar PV systems in urban regions considering the economic and environmental aspects with regard to the PV project owners’ priorities, in addition to the energy-saving context, which was addressed in previous studies. Therefore, this study develops a search space optimization method to find the optimum layout of PV modules on roofs of buildings in urban regions, considering solar PV project owners' economic and environmental priorities. Payback time (PBT) and CO2 emission savings are considered for the economic and environmental criteria calculations, respectively. The results show the significance of owners’ economic and environmental priorities toward PV module arrangement on roofs. Instead of having an entire economic priority, having a 25 % environmental priority enhances annual PV system output and CO2 emission savings about 1.5 times with almost the same PBT.

Accurate modelling of the bifacial gain potential of rooftop solar photovoltaic systems

Bifacial solar modules have emerged as a promising technology in utility-scale photovoltaic systems, experiencing significant growth and capturing a substantial market share worldwide, as reported by the International Technology Roadmap for Photovoltaic (ITRPV) 2023. Despite this progress, the potential of bifacial modules in rooftop applications remains largely unexplored. This paper aims to address this knowledge gap by conducting a comprehensive study utilizing Monte Carlo Ray Tracing techniques coupled with detailed electrical modelling. The primary objective of this study is to investigate the viability of implementing bifacial solar modules on rooftops by examining the potential energy yield gains. By conducting a detailed analysis on a representative rooftop in Canberra, Australia, real-world conditions, and variations are incorporated, providing a more accurate assessment of the energy yield gains achievable in such settings. The simulation results reveal that the implementation of bifacial solar modules on rooftops within Australia can result in energy yield gains of up to 22.6%. These findings demonstrate the considerable potential of bifacial technology in maximizing solar energy production in rooftop applications. The analysis shows significant implications of module and system design on the potential gain. For example, electrical optimisation of individual modules in a system accounted for 1.4% of the bifacial gain. The analysis considers full annual time-step simulation, typical mechanical mounting components, installation orientations and module characteristics, ensuring practical relevance and reliability of the results.

Investigating energy policies to boost grid-connected rooftop solar PV in Sudan

Abstract Grid-connected rooftop solar photovoltaic (PV) systems can reduce the energy demand from the grid and significantly increase the power available to it. However, rooftop solar PV has not yet been widely adopted in many sub-Saharan African countries, such as Sudan, although they are endowed with high solar radiation and in dire need of additional power. This paper investigates risks and policies to increase grid-connected rooftop solar PV adoption in Sudan. A simplified United Nations Development Program Derisking Renewable Energy Investment framework is adopted to investigate this over three stages. For Stage 1, a list of risks and barriers was produced based on a literature review of solar PV studies in Sudan and interviews with nine stakeholders. Affordability was the risk most often mentioned (eight times from nine interviewees), followed by concerns about poor utility grid infrastructure. For Stage 2, policy de-risking instruments and financial de-risking instruments were listed to overcome the barriers. These include the introduction of net metering, the use of a third-party organization to monitor policy implementation, upgrade of the grid infrastructure, public awareness campaigns and energy-saving schemes. For Stage 3, the levelized cost of electricity was estimated for a typical 2-kW rooftop PV system without policies (0.11 $/kWh) and with a net-metering policy (0.07 $/kWh).

Development of novel Cuckoo search optimization-based controller for partially shaded Photovoltaic system

Among the list of reliability issues in Photovoltaic (PV) systems, partial shading is one of the crucial issues that affect the row current creating a wide range of current differences between rows these results in reduced output power and panel life span by creating hotspots. It also creates difficulty in tracking the power, because of multiple hotspot peaks obtainable in PV and IV (Current-Voltage) curves. Physical relocation of panels during shade occurrence is not an encouraging solution because of rooftop solar and domestic PV systems, where the area for PV installation is a ceiling. The optimization-based controller is retrofitted for the electrical relocation of panels. It is developed based on the Cuckoo Search Algorithm (CSA), which aims to reduce the row current difference with a minimum reposition of panels as constraints. For the 9*9 PV arrangement, the row current ranges from 3.747 A to 8.424 A. It is reduced and almost made zero. Hence, the Fill factor raises from 38.073 to 51.707%. The power output is enhanced by about 20%. To prove the algorithm’s novelty a shading case for 4*3 asymmetric array arrangement is also considered for simulation studies. The proposed system proves to be economically beneficent for PV users. The performance of CSA is compared with PSO, Skyscraper, and SuDoKu. An economic analysis is carried out that adds the PV efficiency value to the proposed CSA algorithm. The real-time experimental validation holds good for 3*3 solar array agreement with theoretically simulated results.

Design of Grid-Connected rooftop Photovoltaic system for leakage current reduction using optimization algorithms

Rooftop solar power systems refer to the organization of photovoltaic (PV) panels on the rooftop of a building. They are a feasible substitute for land-based solar arrays, and they are being used in different Asian countries. Thus regulations, grid connectivity, off-take, and land acquisition are the main obstacles that renewable energy plant owners face. At high penetration of rooftop PV, this voltage variability reduces the stability of the grid due to transient imbalance in load and generation and causes voltage and frequency to exceed set limits if not countered by power controls. To reduce this power loss in the transmission cable, a Manta Ray Foraging Optimization (MRFO) process is presented in this research. This method also enhances the PV system's performance. A Non-isolated Buck-Boost Converter is connected between the PV and the grid. For renewable energy applications, a new non-isolated Buck-Boost converter with high voltage gain and positive output voltage has been developed. This converter receives the voltage of input from the PV and gives the output as boosting or lowering the voltage. To improve the current tracking with high power conversion efficiency, a Finite Control Set Model Predictive Controller (FCS-MPC) is introduced for this converter. The proposed optimization algorithm is utilized to tune the controller and improves the dynamic process of the power plant system connected to the grid. This algorithm is simulated using the Matlab Simulink software. The voltage and power generated by the proposed rooftop PV are 560 V and 495.25 kW/sec. The voltage and electricity produced by the ground-mounted are very low compared to the proposed method, therefore, utilizing this rooftop solar PV model, that study generates more power than the ground-mounted PV. This study contributes to the field by improving the energy production of roof-top solar PV systems based on roof design.

Transitioning from illegal rooftop dwellings to solar PV: Market-based incentive design and techno-economic analysis

Renewable energy plays a crucial role in achieving net-zero emissions. As an island with a high population density, Taiwan has increasingly favored rooftop solar photovoltaic (PV) systems over ground-mounted installations due to land-use competition. However, illegal rooftop dwellings in urban areas pose significant obstacles to renewable energy deployment. This study proposes a market-based incentive scheme for rooftop solar adoption to encourage property owners to shift away from illegal rooftop dwellings. We construct market supply curves for illegal rooftop rental housing based on real-world rental data and conduct a techno-economic analysis to examine the required government subsidy. The results provide empirical evidence for an important nonlinearity in the supply curves, implying that linearity-based policy frameworks may not be effective in achieving optimal results. We also identify that opportunity costs linked to rental loss constitute a substantial portion of total costs, deterring the owners from adopting the shift. The findings indicate that the existing feed-in-tariff policy is inadequate to incentivize property owners to deploy rooftop solar panels. The proposed scheme embraces the three dimensions of sustainable development—economic, social, and environmental, which could benefit cities worldwide with illegal rooftop structures.

Low-Voltage Network Modeling and Analysis with Rooftop PV Forecasts: A Realistic Perspective from Queensland, Australia

Recent years have seen a rapid uptake in distributed energy resources (DER). Such technologies pose a number of challenges to network operators, which ultimately can limit the amount of rooftop solar photovoltaic (PV) systems that can be connected to a network. The objective of this industry-based research was to determine the potential network effects of forecast levels of customer-owned rooftop solar PV on Energy Queensland’s distribution network and formulate functions that can be used to determine such effects without the requirement for detailed network modeling and analysis. In this research, many of Energy Queensland’s distribution feeders were modeled using DIgSILENT PowerFactory and analyzed with forecast levels of solar PV and customer load. Python scripts were used to automate this process, and quasi-dynamic simulation (QDSL) models were used to represent the dynamic volt–watt and volt–var response of inverters, as mandated by the Australian Standard AS/NZS 4777. In analyzing the results, linear relationships were revealed between the number of PV systems on a feeder and various network characteristics. Regression was used to form trend equations that represent the linear relationships for each scenario analyzed. The trend equations provide a way of approximating network characteristics for other feeders under various levels of customer-owned rooftop solar PV without the need for detailed modeling.

Sustainable energy development through non‐residential rooftop solar photovoltaic adoption: Empirical evidence from India

AbstractEnvironmental deterioration and climate change are the key issues nowadays that hinder sustainable development, and the consumption of fossil fuel‐based energy sources significantly contributes to the issues. To achieve Sustainable Development Goal‐7 concerning sustainable and clean energy development, deploying non‐conventional energy sources is crucial. Solar energy is considered a significantly clean and sustainable energy source among renewable energy sources. Therefore, the present study attempted to investigate the key factors affecting the adoption of non‐residential Rooftop Solar Photovoltaic (RSPV) systems in Chandigarh, India. The researchers used a descriptive research design to examine the current phenomena. The current study is premised on the perceptions of the users of the non‐residential RSPV system. The data was acquired through a self‐administered survey questionnaire. A complete response from 207 participants was used for analysis purposes. The researchers have used the Partial Least Square‐Structural Equation Modeling strategy to estimate measurement and structural models. The study found that nodal agencies and environmental organizations are crucial in disseminating information and motivations concerning RSPV adoption. The study revealed that the environmental concerns of the users, compatibility, environmental benefits, the immediacy of reward, and trialability were found to be significant drivers of the diffusion and adoption of non‐residential RSPV systems. The study concluded that a paucity of financial incentives and high upfront expenses had been significant blockades to the diffusion and adoption of non‐residential RSPV.

Performance analysis of 600 kWp grid-tied rooftop solar photovoltaic systems at strathmore university in Kenya

Kenya boasts of abundant solar irradiation potential across its expansive regions, averaging between 4.5 kWh/m2 and 6 kWh/m2 per day. Despite this advantageous condition, solar energy's contribution to the national energy mix remains relatively low. To boost solar energy contribution to the national grid, it is crucial to assess the performance of existing grid-tied solar PV systems and develop strategies to improve their energy yields and further help in designing and installing new plants. This paper presents a technical performance analysis of a 600-kWp grid-tied solar PV system at Strathmore University, monitored over one year between January and December 2019. Economic and thermographic analysis of the solar PV system is done. The performance indices studied according to IEC 61724 standard include performance ratio, capacity utilization factor, reference yield, final yield, total collection losses, and total energy yield. This solar plant generated 735 MWh in 2019. The annual average monthly performance ratio, capacity factor, and annual specific energy yield were 57.4%, 13.97%, and 1225 kWh/kWp, respectively. The annual average monthly final yield, array yield, reference yield, and total system collection losses were 3.37 kWh/kWp, 4.49 kWh/kWp, 5.9 kWh/kWp, and 2.53 kWh/kWp, respectively. The thermographic analysis done shows that the system exhibits healthy temperature distribution. The economic analysis demonstrated Levelized Cost of Energy (LCOE) and simple payback period of US$ 0.143/kWh and 9.1 years respectively. The study reveals that the Strathmore system's performance is similar to other solar plants worldwide.

"Москітна флотилія" на енергетичному фронті: малі енергетичні мережі на базі цифрових платформ

In the conditions of Russia's military aggression, the role and importance of measures aimed at ensuring the energy security of the state is growing. The introduction of digital technologies has a significant potential for improving management mechanisms, increasing the reliability and efficiency of both individual components and the country's energy system as a whole. A special place in this process is occupied by the deployment and integration of the sector of local networks of renewable energy generation into the country’s energy system, which are created on the basis of digital platforms. The purpose of the proposed work is to define the potential of digital platforms as a means to coordinate the interaction between private generators of renewable energy in local energy markets. The research tools include structural, functional, systemic and institutional analysis. It is shown that the development of microgrids of renewable energy generation based on digital platforms is able to stimulate radical restructuring of the production system and electricity distribution markets. The author reveals various peculiarities of digital platforms as an organizational form of interaction in local energy markets. It is shown that they provide a synergistic effect of uniting small producers of renewable energy into a microgrid and forming a two-sector model of the public energy system. The structure of microgrid digital platforms is presented. They unite the owners of personal rooftop solar photovoltaic systems, wind, bio-, and hydropower units, power generation surplus storage stations, consumers, and energy distribution companies on the basis of the core platform. The article reveals the mechanism of building energy systems based on the principles of "Industry 4.0". Attention is focused on the need to implement a comprehensive policy to support the platformization of the renewable energy sector. The tools for its provision are presented.

Enhancing energy–climate–economy sustainability in coastal cities through integration of seawater and solar energy

Coastal cities consume 60% of global energy, and seawater-cooled district cooling systems (SWDCS) and rooftop solar photovoltaic systems (SPVS) are effective technologies for utilizing the abundant renewable resources of seawater and solar energy in coastal regions. However, the high investment required for SWDCS and intermittent output from SPVS can limit the quantification of their energy-saving potentials and their large-scale implementation. This study developed GIS data-based methods to map the spatial distribution of carbon abatement costs and a carbon price-based decision tool for achieving optimal co-benefits of integrating SWDCS and SPVS in Hong Kong (the Special Administrative Region of China), Jeddah (Saudi Arabia), and Miami (the USA). These three cities were selected to account for uncertainties associated with different climates and urban characteristics. The carbon abatement costs of SWDCS vary significantly across and between cities, and the carbon mitigation opportunities of SWDCS are much greater than those of SPVS. Integrating the two systems with a carbon price of 250–350 USD/tCO2e would balance carbon mitigation and economic performance to a relatively optimal state in the three cities. This study provides a tailored approach for mapping carbon abatement costs and understanding the co-effects of integrating SWDCS and SPVS in coastal cities, contributing valuable insights into enhancing energy resilience in coastal urban areas with economic and climatic benefits.

Built form and function as determinants of urban energy performance: An integrated agent-based modeling approach and case study

The pursuit of urban energy sustainability is driving growing efforts and pledges to achieve low-energy or net-zero energy performance at urban scales. However, studies covering urban energy performance and renewables integration often lack a systematic consideration of the urban built context (form and function) and its resulting effects on energy demand and supply dynamics. This paper presents a holistic and scalable agent-based modeling framework that incorporates contextual factors in the energy demand and supply evaluation of urban areas using multi-dimensional performance metrics. It leverages the local climate zone (LCZ) classification of typical urban built types, which is commonly used in urban planning or transportation applications (as opposed to energy planning). The framework is demonstrated through a comparative case study of compact high-rise and low-rise urban areas with different proportions of lodging and office buildings equipped with rooftop solar photovoltaic (PV) systems. Results show that the average energy self-sufficiency of the compact low-rise area exceeded 25%. In contrast, the self-sufficiency of the compact high-rise area remained below 5% despite achieving a self-consumption ratio of 99% from locally generated solar energy. The uncovered trends are critical to inform context-sensitive urban energy solutions and policies.

Integration of Centralized and Distributed Methods to Mitigate Voltage Unbalance Using Solar Inverters

Growing penetrations of single-phase distributed generation such as rooftop solar photovoltaic (PV) systems can increase voltage unbalance in distribution grids. However, PV systems are also capable of providing reactive power compensation to reduce unbalance. In this paper, we compare two methods to mitigate voltage unbalance with solar PV inverters: a centralized optimization-based method utilizing a three-phase optimal power flow formulation and a distributed approach based on Steinmetz design. While the Steinmetz-based method is computationally simple and does not require extensive communication or full network data, it generally leads to less unbalance improvement and more voltage constraint violations than the optimization-based method. In order to improve the performance of the Steinmetz-based method without adding the full complexity of the optimization-based method, we propose an integrated method that incorporates design parameters computed from the set-points generated by the optimization-based method into the Steinmetz-based method. We test and compare all methods on a large three-phase distribution feeder with time-varying load and PV data. The simulation results indicate trade-offs between the methods in terms of computation time, voltage unbalance reduction, and constraint violations. We find that the integrated method can provide a good balance between performance and information/communication requirements.

Selecting Rooftop Solar Photovoltaic Modules by Measuring Their Attractiveness by a Categorical-Based Evaluation Technique (MACBETH): The Case of Lithuania

The paper examines the challenges related to solar photovoltaic (PV) development with a pivotal focus on the impacts of the dynamics of the relevant markets and technological advancements in the solar industry. In this regard, household investments into rooftop solar PV modules as one of the available incentives are investigated based on a conducted experiment in Lithuania for selecting rooftop solar PV systems for the prosumer by measuring the attractiveness of solar PV modules by a categorical-based evaluation technique (MACBETH). While a variety of multiple-criteria decision-making (MCDM) methods used by scholars have their specifics in terms of application and the divergence of results, the findings of the conducted experiment reveal MACBETH’s utility when based upon qualitative judgments about the differences in the attractiveness of offers, quantifying their relative value and accordingly ranking the latter. The findings also confirm MACBETH’s potential to be used not only to solve operational and tactical tasks but also for strategic objectives of private and public organizations aiming at competitive and sustainable development in short- and long-term contexts.

Smart inverter and battery storage controls to reduce financial loss due to overvoltage-induced PV curtailment in distribution feeders

The rapid growth of rooftop solar photovoltaic (PV) systems in low-voltage distribution networks has caused reverse power flow leading to voltage rise. As the voltage level increases, PV inverters first reduce the output power to regulate the voltage and may eventually shut down if the voltage level remains above the permissible limit. When this happens, the PV output power is curtailed, leading to financial loss. This paper examines two control strategies to reduce PV curtailment: (1) smart PV inverters and (2) residential battery storage system optimally sized to reduce the cost of household energy. Smart PV inverters can reduce the voltage level by absorbing reactive power at the expense of curtailing its active power output. Residential battery storage can reduce the voltage level by storing excess PV power instead of exporting it to the grid Using these two strategies, a systematic approach is presented to reduce PV curtailment and the associated financial loss. Three types of electricity tariffs are used, namely, electricity market pool price, and retail flat and time of use tariffs for household customers. An 11-kV distribution feeder in South Australia is analysed with the prevailing feeder and inverter voltage limits per Australian regulatory standards. The results demonstrate that installing 100% of PV systems with smart inverters and optimally sized battery storage can reduce the PV curtailment and the corresponding financial losses by 47%.

A behavioral study on villagers’ adoption intention and carbon neutrality toward rooftop solar photovoltaic systems in India

PurposeThis study aims to examine the determinants of adoption intention toward the rooftop solar photovoltaic (RSPV) systems among residents of peri-urban villages of Gurugram, Haryana, India. This study also analyzes the impact of the adoption of RSPV systems on carbon neutrality from a behavioral perspective.Design/methodology/approachData was collected using a self-administrated structured questionnaire from 208 male villagers (195 usable) of 22 villages using the purposive sampling technique.FindingsResults revealed that relative advantage, followed by simplicity, trialability, observability and compatibility, positively and significantly impact villagers’ attitude toward adopting RSPV systems in their homes. Perceived severity and perceived vulnerability significantly influence the perceived behavioral control of villagers toward adopting the RSPV systems. The results show villagers’ attitudes, subjective norms and perceived behavioral control are the essential predictors of their adoption intention of the RSPV systems. Most notably, carbon neutrality was significantly affected by villagers’ adoption intention of RSPV systems as the renewable energy source in their homes.Originality/valueThe findings of this study provide that innovation attributes are important factors in shaping the adoption intentions of customers toward RSPV systems. This study is also the extent of previous studies measuring customers’ perception of adopting renewable energy in developed and emerging countries worldwide.

Solar for renters: Investigating investor perspectives of barriers and policies

Rooftop solar photovoltaic (PV) systems present households with a way to reduce their energy bills, while contributing to a clean energy transition. However, rental properties are considerably less likely to have solar PV. It is unclear whether current policies that focus on reducing upfront costs to installing solar PV address the barriers perceived as most important by property investors. Using a best-worst scaling survey of 931 property investors, we find that investors on average view renters being unwilling to pay higher rents for properties with solar PV equally as important as affordability concerns as barriers to investment. Owners of apartments or townhouses focus on structural barriers. Our discrete choice experiment of 147 property investors shows that policies that spread solar system payments over time and direct feed-in tariff revenue to property investors are not preferred by most owners of fully-detached rental dwellings. We conclude by stressing the importance of policies that reduce information asymmetries from the property investor perspective regarding the value that renters place on PV systems. There is also a need for policies to better address barriers faced by owners of apartments and townhouses.

Simulating the Diffusion of Residential Rooftop Photovoltaic, Battery Storage Systems and Electric Cars in Italy. An Exploratory Study Combining a Discrete Choice and Agent-Based Modelling Approach

Rooftop solar photovoltaic (PV) systems could significantly contribute to renewable energy production and reduce domestic energy costs. In Italy, as in other countries, the current incentives generate a modest annual increase after the generous fiscal incentives that kick-started the PV market in the 2008–2013 period. Several factors are, however, at play that can speed up the installation process, such as the improvements in PV technology at declining prices, the increased availability of battery-storage (BS) systems, the growing use of electric appliances, the uptake of electric cars, and the increased environmental awareness. We integrate two research methodologies, discrete choice modeling and agent-based modeling, to understand how these factors will influence households’ decisions regarding PV and BS installations and how agents interact in their socioeconomic environment. We predict that in Italy, given the preference structure of homeowners, the continuing decline in costs, and the social interaction, 40–45% of homeowners will have PV or PV and BS installed by 2030, thanks to the existing investment tax credit policy.