Research on the influence of PV cell to thermal characteristics of photovoltaic/thermal solar system

In the paper, we analyzed internal thermal transmission characteristics of water‐heating photovoltaic/thermal (PV/T) solar collector covered by photovoltaic (PV) cell, established photothermal conversion model of PV/T solar system, and analyzed the influence of PV cell coverage to photothermal characteristics of PV/T solar system. Results show that the thermal efficiency of PV/T solar system by optimizing PV cells coverage can reach 68%. In addition, by designing four water‐heating PV/T solar system prototypes with PV cell coverage of 0.4, 0.56, 0.7, and 0.82, respectively, we conducted experimental researches for the four prototypes and found that the four prototypes can achieve thermal efficiencies of 58%, 51%, 64%, and 67%, respectively, in heating 250 L of water to 50°C. The experiment results are consistent with theoretical analysis results, indicating that it is feasible to improve thermal characteristics of PV/T solar system by optimizing PV cell coverage. Copyright © 2017 John Wiley & Sons, Ltd.     

Measuring the rebound effect: A case study of residential photovoltaic systems in San Diego

This study examines the effect of solar photovoltaic system installation on the electricity consumption in residential households across various geographic regions in San Diego. Using meter-level data, the electricity consumption for residential households is calculated before and after installation to assess whether there are any significant rebound effects in usage. Results reveal significant variations in the change in electricity usage depending on geographical location. The findings are relevant to regional resource planning and climate response, as the failure to account for the rebound effect may result in significant overestimation of the energy and emissions benefits of distributed renewable energy adoption.     

Increasing the efficiency of PV panel with the use of PCM

The article presents how to increase electrical efficiency and power output of photovoltaic (PV) panel with the use of a phase change material (PCM). The focus of the work is in experimental setup and simulation heat extraction from the PV panel with the use of TRNSYS software. A modification of PV panel Canadian Solar CS6P-M was made with a phase change material RT28HC. The actual data of cell temperature of a PV panel with and without PCM were given and compared. A simulation of both PV panels in TRNSYS software was performed, followed by the comparison of results with the simulation and experimental actual data. The experimental results show that the maximum temperature difference on the surface of PV panel without PCM was 35.6 °C higher than on a panel with PCM in a period of one day. Referring to experimental results the calculation of the maximum and average increase of electrical efficiency was made for PV-PCM panel with TRNSYS software. Final results of simulation shows that the electricity production of PV-PCM panel for a city of Ljubljana was higher for 7.3% in a period of one year.     

On the impact of haze on the yield of photovoltaic systems in Singapore

Anthropogenic haze, caused at least in parts by forest and agricultural land clearing fires in Sumatra (Indonesia), is occasionally causing air quality issues in Singapore, located 150–300 km east of the majority of these “hot spots”. The resulting air pollution partially blocks sunlight from reaching the ground, and consequently affects the electric power generation of solar photovoltaic (PV) systems in Singapore. In this work, a methodology is presented to estimate the haze-induced reduction of the light intensity reaching PV panels and the corresponding loss in the electric energy yield. An assessment of a major haze event in June 2013 is the basis for the loss analysis, which takes into account data filtering techniques in order to isolate cloudless conditions for inter-comparison between clear and hazy days. Data from previous years in non-hazy conditions serve as baseline for the determination of the clear sky conditions for Singapore. The novel method is further applied to investigate the power output of ten PV systems in Singapore during the June 2013 haze event. It is found that poor air quality levels during this event caused yield losses of PV systems in Singapore in the range of 15–25%.     

Business models and financing options for a rapid scale-up of rooftop solar power systems in Thailand

Diverse solar PV business models and financing options exist in the international landscape, helping expand and accelerate the adoption of rooftop solar PV systems. The conditions for their emergence are context specific, depending on the policies, regulations, incentives, and market conditions of each country. After a review of the international landscape, this paper compiles and analyzes business models and financing options for rooftop solar PV investment in Thailand that have emerged during the period between 2013 and 2015. Despite policy discontinuity for the support of rooftop solar systems, diverse business models and financing options are driving market expansion and expanding solar access to more Thai consumers. Drawing on our policy and regulatory analyses and in-depth interviews with business representatives, we identify four types of business models and one financing option. The business models include Roof Rental, Solar PPA, Solar Leasing, and Community Solar, and the financing option is the solar loan. We analyze the drivers for their emergence, barriers to their success, and the risks from the business owners' and consumers' viewpoints. Our policy recommendation is focused on crafting a net-metering regulation with evidence-based studies on the potential costs and benefits to different stakeholders.     

Siting of PV power plants on inclined terrains

Most of the studies conducted on solar energy assessment and solar system siting focus on flat terrains that are usually difficult and expensive to acquire in urban areas. This paper investigates the possibility of using inclined terrains for siting photovoltaic (PV) power plants surrounding urban area. Both analytical analysis and simulations are carried out in order to analyse and validate the effectiveness and benefits of the use of inclined land for PV siting. Geographical information system and numerical weather prediction were used to implement the suggested original approach and to select suitable inclined terrains for the PV system installation and to calculate the total generation potential for energy production. Muscat, the capital of Oman, was selected as a reference for the implementation of this approach.     

Regulatory and ratemaking approaches to mitigate financial impacts of net-metered PV on utilities and ratepayers

The financial interests of U.S. utilities are poorly aligned with customer-sited solar photovoltaics (PV) under traditional regulation. Customer-sited PV, especially under a net-metering arrangement, may result in revenue erosion and lost earnings opportunities for utility shareholders as well as increases in average retail rates for utility ratepayers. Regulators are considering alternative regulatory and ratemaking approaches to mitigate these financial impacts. We performed a scoping analysis using a financial model to quantify the efficacy of mitigation approaches in reducing financial impacts of customer-sited PV on utility shareholders and ratepayers. We find that impacts can be mitigated through various incremental changes to utility regulatory and business models, though the efficacy varies considerably depending on design and particular utility circumstances. Based on this analysis, we discuss tradeoffs policymakers should consider, which ultimately might need to be resolved within broader policy contexts.     

An analytical-numerical approach for parameter determination of a five-parameter single-diode model of photovoltaic cells and modules

Parameter extraction of the five-parameter single-diode model of solar cells and modules from experimental data is a challenging problem. These parameters are evaluated from a set of nonlinear equations that cannot be solved analytically. On the other hand, a numerical solution of such equations needs a suitable initial guess to converge to a solution. This paper presents a new set of approximate analytical solutions for the parameters of a five-parameter single-diode model of photovoltaic (PV) cells and modules. The proposed solutions provide a good initial point which guarantees numerical analysis convergence. The proposed technique needs only a few data from the PV current-voltage characteristics, i.e. open circuit voltage V_oc, short circuit current I_sc and maximum power point current and voltage I_m; V_m making it a fast and low cost parameter determination technique. The accuracy of the presented theoretical I–V curves is verified by experimental data.     

Estimation of the PV potential in ASEAN with a high spatial and temporal resolution

Further exploitation of renewable energy sources for power generation could mitigate the current rapid increase of greenhouse gas emissions in South East Asia. In this context, solar PV is a promising option as PV system costs have been declining continuously over the past. In order to define strategies towards a low-carbon future power supply, detailed information on the potential power output of solar PV is essential.Therefore, this paper analyses the resource and technical potential of solar PV in South East Asia in high temporal and spatial resolution. An empirical, climate-based Ångström-Prescott model is proposed in order to adjust MERRA solar radiation data. The possible power output of PV is derived considering topographic and land-use constraints as well as technological characteristics of typical PV systems.Java, central Myanmar and eastern Thailand were identified to be the best locations for PV use, with capacity factors exceeding 15%. Due to the large land area which is suitable for PV installations, South East Asia offers an abundant theoretical potential of solar PV, amounting to 430 TW h with conservative assumptions.     

Impact of flat roof–integrated solar photovoltaic installation mode on building fire safety

This paper quantifies experimentally the fire‐induced reradiation to roof surface created by flame extension on the back of the flat roof–integrated photovoltaic (PV) array. A gas burner underneath the tilted PV panels was employed as the fire source. The effects of the PV tilt angle, distance from PV panel to roof, and fire heat release rate (HRR) were investigated. The flame extension geometries and flame reradiation heat flux distribution were recorded. The results show that the flame extension length and vertical thickness (ie, the vertical distance from the back surface of the PV panel to the extension flame profile) are reduced with the increase of PV tilt angle and panel‐roof distance but are increased with increases in the fire HRR. A unified nondimensional HRR coupled with all these factors is proposed to quantify the flame extension geometry. Furthermore, a general equation based on the physical relationship between flame radiation and flame geometry is developed to characterize the distribution of reradiation heat flux on the roof surface with the nondimensional local flame thickness. Finally, suggestions regarding PV installations on flat roofs and the selection of roofing materials are given to decrease the possibility of flame propagation underneath the PV arrays.