Residential Rooftop Research Articles

Economic analysis of grid-connected residential rooftop PV systems in Turkey

This study presents an economic analysis of grid-connected residential rooftop PVs in Turkey under the current feed-in tariff (FiT) scheme. Three solar parts are formed on the solar map of Turkey to discuss the effect of solar radiation differences between regions on the feasibility of the systems. Nine provinces are selected for a nationwide analysis. 5 kW rooftop PVs are simulated using HOMER Grid. Discounted Payback Period (DPBP), Internal Rate of Return (IRR) and Profitability Index (PI) are used to ensure the viability of the systems from all aspects. DPBP below 8 years, IRR above 13.12%, and PI above 2 are considered feasible.The results showed that current DPBP, IRR, and PI of the systems are in the range of 7.75–14.43 years, 13.68%–6.87%, and 2.02–1.28, respectively. The systems are attractive only in one province in the southern part, and far from being investable in the northern part. A sensitivity analysis is performed to analyze the effect of varying FiT and PV initial cost on the feasibility of the systems and make policy implications. It is recommended to increase the amount of residential PV incentives in Turkey and develop a regional support mechanism, considering solar differences between regions.

Nonparametric Kullback-divergence-PCA for intelligent mismatch detection and power quality monitoring in grid-connected rooftop PV

In parallel to sustainable growth in solar fraction, continuous reductions in Photovoltaic (PV) module and installation costs fuelled a profound adoption of residential Rooftop Mounted PV (RMPV) installations already reaching grid parity. RMPVs are promoted for economic, social, and environmental factors, energy performance, reduced greenhouse effects and bill savings. RMPV modules and energy conversion units are subject to anomalies which compromise power quality and promote fire risk and safety hazards for which reliable protection is crucial. This article analyses historical data and presents a novel design that easily integrates with data storage units of RMPV systems to automatically process real-time data streams for reliable supervision. Dominant Transformed Components (TCs) are online extracted through multiblock Principal Component Analysis (PCA), most sensitive components are selected and their time-varying characteristics are recursively estimated in a moving window using smooth Kernel Density Estimation (KDE). Novel monitoring indices are developed as preventive alarms using Kullback-Leibler Divergence (KLD). This work exploits data records during 2015–2017 from thin-film, monocrystalline, and polycrystalline RMPV energy conversion systems. Fourteen test scenarios include array faults (line-to-line, line-to-ground, transient arc faults); DC-side mismatches (shadings, open circuits); grid-side anomalies (voltage sags, frequency variations); in addition to inverter anomalies and sensor faults.

Deploying residential rooftop PV units for office building use: a case study in Shanghai

The utilization of distributed power generation system plays an essential role in the design of resilient cities. With the ever increasing of efficiency and decreasing of production cost, Photovoltaic (PV) system is becoming a globally welcomed city component. During the design of PV systems, the matching of demand and supply power curve is critical. This paper evaluates the PV usage potential in different neighborhoods of Shanghai through matching the rooftop PV generation profile with the electricity demands of office buildings. The typical electricity use pattern of an office building is calculated by clustering method with data from a sub-metering platform, and PV generation curve is generated through simulation approach. Case studies were done in 140 neighborhoods of Shanghai City, and theoretical self-utilization ratio and PV utilization of each neighborhood were calculated.

Estimation of satellite‐derived regional photovoltaic power generation using a satellite‐estimated solar radiation data

AbstractA large number of photovoltaic (PV) power systems have been adopted in Japan after a feed‐in tariff was introduced in 2012. However, PV power generation data from residential rooftop and/or ground‐mounted PV systems, and larger MW‐size PV plants have not been measured accurately in real‐time. This is because PV power monitoring instruments (eg, smart meters) have not collected a sufficient amount of power generation data. In order to realize adequate safety control of electric power systems under high PV‐penetration conditions, it is important to fully understand the temporal and spatial variations associated with PV power generation. In this study, we estimated the PV power generation for a regional area (ie, prefecture or municipality) in terms of PV power installation capacity and satellite‐estimated solar irradiance using a Japanese geostationary satellite, Himawari‐8. The satellite‐derived regionally integrated PV power estimations were validated with reference data provided by electric power companies. The validation results showed that these estimations were comparable to the reference data, provided by the Kyushu Electric Power Company Inc. (Kyushu) and the Tokyo Electric Power Company Inc. (TEPCO). However, the results also identified slight overestimations of PV power in the spring and summer seasons. An advantage of the proposed method is that it does not require land‐based monitoring instruments, which can lead to increased operational cost savings for PV power systems. Furthermore, in consideration of future PV power penetration scenarios, it is suggested that PV power in excess of regional power demands could be generated under the same weather conditions.

Rainwater harvesting, a measure to meet domestic water requirement; a case study Islamabad, Pakistan.

Pakistan is located in the semi-arid region of the world where water scarcity is a major issue. In such areas, rainwater harvesting (RWH) is considered to be the best alternate source of domestic water supply. Rainwater harvesting is being considered as an integral part of the sustainable water management in many parts of the world. Rainfall patterns in arid areas are typically highly variable, both spatially and temporally. Hence, there is always a need to evaluate rainwater harvesting keeping in view the seasonal variations for a specific area. In rainwater harvesting, a mechanism is designed to collect surface runoffs effectively during rainfall events from residential rooftops. In this paper, it has also been analyzed that rainwater has a great potential to be taken as a source of water demands in residential colonies of major cities like Islamabad being our study area. Here, 116 m2 (five marlas) housing pocket has been considered as a model site for which various water demands have been calculated depending upon residential needs and horticulture requirements of the study pocket. Rainwater from rooftops has been used to reduce freshwater needs of the houses. As a result, residential water demands for fresh water have reduced by almost 22% average.

Maxmize the House Roof PV Solar Output by Using Maximum Power Point Box (MPPB)

Abstract Renewable energy is becoming an essential element when it comes to climate change greenhouse issues. To aid in reducing the CO2 emission into the environment, numerous governments support individual investments in solar system on their residential rooftop. A set of regulations were established by the local utilities to control and manage the input energy power into the grid from the rooftop-installed solar system. One of the main regulation is the maximum allowable size of the single-phase solar inverter. The solar inverter size has direct impact on the maximum PV panels installed on the house rooftop, which control the house maximum electrical output power. In addition, the solar panels are solidly fixed on the house roof, which doesn’t allow to track the sun energy during the day. This also reduces the house output power during a nominal period throughout the day. The study in this paper introduces the maximum power point box that allow the house owner to maximize the output energy during the morning, midday and afternoon period without the need to upgrade the inverter or the single phase system for the house. Also the proposal allows for more efficient building integration between solar panels and building design, which reduces the cost of the proposed system. Case study is also included.

Suitability of representative electrochemical energy storage technologies for ramp-rate control of photovoltaic power

Photovoltaic (PV) systems can exhibit rapid variances in their power output due to irradiance changes which can destabilise an electricity grid. This paper presents a quantitative comparison of the suitability of different electrochemical energy storage system (ESS) technologies to provide ramp-rate control of power in PV systems. Our investigations show that, for PV systems ranging from residential rooftop systems to megawatt power systems, lithium-ion batteries with high energy densities (up to 600 Wh L−1) require the smallest power-normalised volumes to achieve the ramp rate limit of 10% min−1 with 100% compliance. As the system size increases, the ESS power-normalised volume requirements are significantly reduced due to aggregated power smoothing, with high power lithium-ion batteries becoming increasingly more favourable with increased PV system size. The possibility of module-level ramp-rate control is also introduced, and results show that achievement of a ramp rate of 10% min−1 with 100% compliance with typical junction box sizes will require ESS energy and power densities of 400 Wh L−1 and 2300 W L−1, respectively. While module-level ramp-rate control can reduce the impact of solar intermittence, the requirement is challenging, especially given the need for low cost and long cycle life.

Flat Concentrator Photovoltaic System with Lateral Displacement Tracking for Residential Rooftops

We present a design for a flat concentrating photovoltaic (CPV) system that requires only lateral displacement for sun-tracking, intended for residential rooftop applications. Compared with flat-plate photovoltaics (PVs), CPV technology is essential for reducing the use of semi-conductor materials, which also enables cheaper solar power generation. Existing CPV designs are more bulky and complex than traditional PV panel techniques and are therefore better suited to solar farms than rooftop use. In this study, we explore an alternate approach, employing a mirror-coated lenslet array, to demonstrate a flat CPV system for rooftop installation. This mirror-coated lenslet array collects solar radiation and concentrates it with a very short focal length. The lateral movement of lenslet focal points according to a changing incident angle of sunlight allows for the use of a lateral displacement tracking mechanism. A square array of solar cells integrated on a transparent sheet is placed on top of a mirror-coated lenslet array to collect focused sunlight and convert it to electricity. The proposed CPV panel can be achieved with a 35 mm thickness. Simulation models were developed using commercial optical design software (LightTools). The simulation demonstrates an optical efficiency of up to 89.5% when the concentration ratio of the system is fixed to 50×. The simplicity of the structure enables cheaper mass production. Our quest for a lateral displacement sun-tracking mechanism also shows that the system has a high tolerance, thereby enabling cost savings by replacing a highly precise, active sun-tracking system with a lower-accuracy system. The presented flat CPV is a strong candidate for a low-cost, high-efficiency solar energy system that can be installed on the rooftops of residential buildings to deliver energy savings.

Analysis of the Performance Indicators of the PV Power System

The energy assessment of the PV power systems is carried out by using different types of performance indicators that benchmark the output of these systems against the PV panel maximum output at hypothetical operation conditions. In this paper, a comparative analysis of six types of performance indicators is conducted and a new performance indicator which considers PV panel slope and orientation is proposed. The proposed indicator is benchmarking the PV system actual output against the maximum output of the same system if it would operate in two axis tracking mode. The proposed performance indicator is used to develop a friendly user calculator of PV system output that can be used by, energy providers and PV system installers to evaluate the output of the PV grid connect network. The advantage of the developed calculator is high-lighted by a case study that estimates energy capacity of different residential rooftop PV systems installed in a residential suburb in Sydney.

Solar Residential Rooftop Systems (SRRS) in South Delhi : A Strategic Study with Focus on Potential Consumers' Awareness

Delhi, the capital of India is receiving 89 per cent of its power from thermal power plants. Due to rapid depletion of fossil fuels and environment pollution, government introduced Delhi Solar Energy Policy. The objective of the policy is to shift from thermal to solar power generation through installation of 2GW of solar rooftop systems by FY25. Accordingly, there is potential of producing 49 per cent of solar power through Solar Residential Rooftop Systems (SRRS). For achieving this, there is need of synergy between two major stakeholders i.e. government and potential consumers (owners of residential units). The major provision of the policy is to provide financial subsidies, technical support and generation based incentives to encourage residential roof owners for the installations of SRRS. Still the installations of SRRS are dismally low. Apart from the formulation of policy; the awareness factor plays pivotal role enabling roof owners to take informed quality decision. The main contribution of this research paper is to explore the awareness levels of potential consumers for the SRRS as well as about government subsidies towards SRRS installations. The average awareness score on a scale of 1 to 5 about SRRS has been found significantly low i.e. 1.99. This study revealed that there was no relationship between awareness level and demographic profile of respondents. The awareness of people towards government subsidy has also been found quite low. In view of the research outcomes, there is need to disseminate information (through strategic advocacy) about government incentives and SRRS, among residential owners for achieving the targets of the policy.

Impact of Distributed Rooftop Photovoltaic Systems on Short-Circuit Faults in the Supplying Low Voltage Networks

This article evaluates the effect of randomly distributed, residential single-phase rooftop photovoltaic systems in the low voltage residential networks, during short-circuit faults on the overhead lines. The important parameters such as the fault current, the current sensed at the distribution transformer secondary, and the voltage profile along the feeder during the fault are examined. A sensitivity analysis is carried out in which the rating and location of the photovoltaic systems in the feeder, as well as the fault location and type, are the considered variables. Moreover, to demonstrate the effect of multiple photovoltaic systems with different ratings and penetration levels when distributed unequally among three phases of the network, a stochastic analysis is carried out. The article summarizes the outcomes of these two analyses to provide a better understanding of the impact of single-phase rooftop photovoltaic systems on the residential feeders during short-circuit faults.

Energy Security: Shaping the Consumer Decision Making Process in Emerging Economies

Energy security is a universal concern among all countries, with all nations struggling for a sustainable solution. Solar technologies are a particularly beneficial utility for emerging economies due to both geography and affordability. Solar Photovoltaics (PV) is one of the highest potential growth markets in emerging economies due to the ability for small-scale systems to be placed on residential rooftops. Distribution of PV to individual homeowners is a new buying and selling process for what has traditionally been a business-to-business marketplace. Because the consumer market is at an infant stage in emerging economies, the messages that PV companies send to consumers will ultimately shape consumer perception about renewable energy. Through content analysis of websites from 12 companies in two of the BRICS markets, this research explores the similarities and differences with regard to consumer-facing messages among companies of various sizes in the two markets.

Photovoltaic Power Potential Analysis in Equator Territorial: Case Study of Makassar City, Indonesia

Solar power energy in some countries can be the most potential renewable energy to overcome lack of energy and environmental problems. Indonesia is one of the examples. One of the promising cities to install photovoltaic (PV) systems is Makassar, which has average 5.83 kWh/m2/day of solar irradiance (Meyta, 2011). However, until 2016, there is still no solar panel installation in Makassar (PLN, 2015). In addition, general lack of research in assessing potential of PV systems in Makassar makes PV system difficult to develop. This study therefore set out to assess PV system potential in Makassar which its objectives are to determine 1) total available area for rooftop and large-scale PV systems in Makassar, 2) economy feasibility and 3) environmental impact due to PV installation. Three cases have been analyzed in this study, first, PV systems for residential rooftop, second, PV systems for large-scale (mega solar) in Makassar, and third, PV systems for large scale in outside Makassar and radius 20 km from center of Makassar. ArcGIS10.3 software is carried out to estimate available area for PV installation. Furthermore, RetScreen 4 software was used to conduct PV system capacity and its energy yield and to evaluate economy analysis such as internal rate of return and cost of energy. As the result, the total available area for residential rooftop PV system is evaluated to be 13.8 km2, which potential installed capacity is estimated to be 2044 MW. Total available area for large-scale PV system in Makassar and outside Makassar are 19.3 km2 and 231.3 km2, which estimated 851 MW and 10,179 MW of installed capacity, respectively.

Economic competitiveness of III–V on silicon tandem one‐sun photovoltaic solar modules in favorable future scenarios

AbstractTandem modules combining a III–V top cell with a Si bottom cell offer the potential to increase the solar energy conversion efficiency of one‐sun photovoltaic modules beyond 25%, while fully utilizing the global investment that has been made in Si photovoltaics manufacturing. At present, the cost of III–V cells is far too high for this approach to be competitive for one‐sun terrestrial power applications. We investigated the system‐level economic benefits of both GaAs/Si and InGaP/Si tandem modules in favorable future scenarios where the cost of III–V cells is substantially reduced, perhaps to less than the cost of Si cells. We found, somewhat unexpectedly, that these tandems can reduce installed system cost only when the area‐related balance‐of‐system cost is high, such as for area‐constrained residential rooftop systems in the USA. When area‐related balance‐of‐system cost is lower, such as for utility‐scale systems, the tandem module offers no benefit. This is because a system using tandem modules is more expensive than one using single‐junction Si modules when III–V cells are expensive, and a system using tandem modules is more expensive than one using single‐junction III–V modules when III–V cells are inexpensive. Copyright © 2016 John Wiley & Sons, Ltd.

A National Certification Scheme to Enhance Trust and Quality in the Indian Residential Solar PV Market

India has recently committed to install 100 GW of solar power by 2022, the principal component of its climate policy agenda. But the pace of solar adoption in the residential rooftop sector — the success of which is important for local job creation and sustaining political support for India’s broader climate goals — has been sluggish, notwithstanding government efforts to jumpstart the market. At the core of the residential solar market’s dysfunction is a negative spiral of low-quality solar installations and consumer distrust that fuel one another. Quality and trust are essential drivers of successful technology diffusion, and the emergence of trusted brands can drive a virtuous cycle rather than a vicious one. A promising solution to enable a virtuous cycle is a third-party certification scheme, which could instill trust in consumers by designating solar providers with a proven track record and competent technicians. India’s government should implement a voluntary, two-level certification scheme that accredits individual technicians as well as solar providers and makes the certifications publicly available. If the government can leverage best practices from around the world, avoid over-regulation, and deter corruption, then India’s residential solar market could finally take off.

Data-driven agent-based modeling, with application to rooftop solar adoption

Agent-based modeling is commonly used for studying complex system properties emergent from interactions among many agents. We present a novel data-driven agent-based modeling framework applied to forecasting individual and aggregate residential rooftop solar adoption in San Diego county. Our first step is to learn a model of individual agent behavior from combined data of individual adoption characteristics and property assessment. We then construct an agent-based simulation with the learned model embedded in artificial agents, and proceed to validate it using a holdout sequence of collective adoption decisions. We demonstrate that the resulting agent-based model successfully forecasts solar adoption trends and provides a meaningful quantification of uncertainty about its predictions. We utilize our model to optimize two classes of policies aimed at spurring solar adoption: one that subsidizes the cost of adoption, and another that gives away free systems to low-income households. We find that the optimal policies derived for the latter class are significantly more efficacious, whereas the policies similar to the current California Solar Initiative incentive scheme appear to have a limited impact on overall adoption trends.

Estimating Solar PV Potential for Sustainable Energy Planning in Tier-II Cities of India: Case of Bhopal City

With growing economy, several cities and towns in India are experiencing a substantial growth in their gross and peak electricity demands. While Municipal Corporations and the electricity supply agencies are struggling to cope with growing energy demand of cities, many think solar electricity generation through rooftop Photovoltaic (PV) is a viable solution for this problem. Quantification of available rooftop is necessary to estimate the potential of energy generation in Indian cities through rooftop solar PV panels. This paper proposes an automated object-oriented approach to extract total available area of residential rooftops. A smaller residential neighbourhood in Bhopal city has been selected as Test Site to test the proposed method. Data sets used are World View 2 Stereo pair and Multispectral images. It is found that the test area has the potential to meet 265% of its daily local energy demand through rooftop solar PV panels. Though Indian government had announced separate scheme under the Jawaharlal Nehru National Solar Mission (JNNSM) to promote installation of rooftop PV, development of this sector is still in nascent stages. This paper also suggests some policy level interventions to promote rooftop PV at domestic level in similar tier-II cities of India.

Optimal Photovoltaic Resources Harvesting in Grid-connected Residential Rooftop and in Commercial Buildings: Cases of Thailand

Photovoltaic (PV) has recently undergone impressive growth and substantial cost decreases. A single-crystal silicon (mono-Si) or polycrystalline (poly-Si) have been dominant for solar rooftop and in commercial buildings installation in the past years. However until recently thin-film PV modules both amorphous silicon (a-Si) and other non-silicon thin films technology have been advance efficiency developments with low cost. The competition of crystalline and thin film solar panel technologies drives the cost significantly decreased and helps the solar investors for a good financial profit return for a shorter time. This study by satellite-derived data, Solar GIS pvPlanner software shows that the highest output is in a-Si, CdTe and followed by CIS, and c-Si PV modules for the locations considered in this study. The average energy output of amorphous panels in residential solar rooftop installed in Bangkok has the highest values of 1,503 kWh/kWp. The average energy output of amorphous panels in commercial building installed in Chonburi province has the highest values of 1,601 kWh/kWp. The optimal inclination angle is 15° south direction in both areas. Finally, the economic assessment of solar panels is also investigated for the feasibility investment by RETscreen model.

Rooftop Surface Temperature Analysis in an Urban Residential Environment

The urban heat island (UHI) phenomenon is a significant worldwide problem caused by rapid population growth and associated urbanization. The UHI effect exacerbates heat waves during the summer, increases energy and water consumption, and causes the high risk of heat-related morbidity and mortality. UHI mitigation efforts have increasingly relied on wisely designing the urban residential environment such as using high albedo rooftops, green rooftops, and planting trees and shrubs to provide canopy coverage and shading. Thus, strategically designed residential rooftops and their surrounding landscaping have the potential to translate into significant energy, long-term cost savings, and health benefits. Rooftop albedo, material, color, area, slope, height, aspect and nearby landscaping are factors that potentially contribute. To extract, derive, and analyze these rooftop parameters and outdoor landscaping information, high resolution optical satellite imagery, LIDAR (light detection and ranging) point clouds and thermal imagery are necessary. Using data from the City of Tempe AZ (a 2010 population of 160,000 people), we extracted residential rooftop footprints and rooftop configuration parameters from airborne LIDAR point clouds and QuickBird satellite imagery (2.4 m spatial resolution imagery). Those parameters were analyzed against surface temperature data from the MODIS/ASTER airborne simulator (MASTER). MASTER images provided fine resolution (7 m) surface temperature data for residential areas during daytime and night time. Utilizing these data, ordinary least squares (OLS) regression was used to evaluate the relationships between residential building rooftops and their surface temperature in urban environment. The results showed that daytime rooftop temperature was closely related to rooftop spectral attributes, aspect, slope, and surrounding trees. Night time temperature was only influenced by rooftop spectral attributes and slope.

The Future of Solar Power in the United Kingdom

We used detailed industry data to analyse the impacts of expected further cost reductions on the competitiveness of solar power in Britain, and assess whether the solar market can survive without support in the near future. We investigated three solar power markets: large-scale, ground-mounted “solar farms” (defined in our analysis as larger than a 5000 kilowatt system); commercial roof-top (250 kW); and residential rooftop (3 kW). We found that all three would be economic without support in the next decade. Such an outcome assumes progressively falling support under a stable policy regime. We found that unsubsidised residential solar power may be cheaper with battery storage within the next five to 10 years. Unsupported domestic solar battery packs achieve payback periods of less than 10 years by 2025. That could create an inflexion point driving adoption of domestic solar systems. The variability of solar power will involve some grid integration costs at higher penetration levels, such as more frequent power market scheduling; more interconnector capacity; storage; and backup power. These costs and responses could be weighed against non-market benefits including the potential for grid balancing; lower carbon and particulate emissions; and energy security.