Impact of heated PV modules on soiling behavior and energy yield

Bifacial photovoltaics (BPVs) are emerging with large momentum as promising solutions to improve energy yield and cost of PV systems. To reach its full potential, an accurate understanding of the physical characteristics of BPV technology is required. For this reason, we collected experimental data to refine a physical model of BPV. In particular, we simultaneously measured the module temperature, short circuit current (Isc), open-circuit voltage (Voc), power at the maximum power point (Pmpp), and the energy yield of a bifacial and a monofacial minimodule. Such minimodules, realised with the same geometry, cell technology, and module lamination, were tested under the same clear sky outdoor conditions, from morning to afternoon, for three days. The bifacial system experimentally shows higher module temperatures under operation, about 10 °C on a daily average of about 40 °C. Nevertheless, its energy yield is about 15% larger than the monofacial one. We propose a physical quantitative model that fits the experimental data of module temperature, Isc, Voc, Pmpp, and energy yield. The model was then applied to predict the annual energy yield of PV module strings. The effect of different PV module temperature coefficients on the energy yield is also discussed.

One of the current technologies widely used to extract the earth’s renewable energy is solar modules, which harness energy from the sun; however, their operating conditions and their energy storage capacities vary greatly under different weather conditions. The high-speed Flywheel Energy Storage System (FESS) presents a promising prospective solution for solar energy storage and utilization. Accurately modeling FESS can lead to its efficient design and control. In this paper, a fully integrated FESS, with comprehensive photovoltaic (PV) system, has been modeled to simulate the overall energy harvesting capabilities, power output, and efficiency. The solar module has been modeled using the one-diode solar cell model technique to predict the overall system efficiency and determine the most efficient time of day for switching between the FESS’s charging (morning time) and discharging mode (night time). To validate the developed model using experimental data, four 250 Wp Ankara Solar PV modules and a Balance of System (BOS) were installed. The solar irradiance, wind speed, cell temperature, solar module, FESS output voltage and current were logged during the system’s operation. The theoretical model predicted that the energy output for the test day was 4.80 kWh, while the experimental analysis showed that the solar modules produced 4.68 kWh, only 2.5% percentage difference. The theoretical and experimental power curves followed the same trends throughout the day, which assures that the model could accurately predict the daily energy output of the solar array. The efficiency of the solar module was determined to be 15.3%. The solar module simulation serves as a repeatable replication of the actual solar module source, which enables convenient, low-cost estimation of the solar module-FESS system under different environmental conditions. The developed solar module was integrated with a brushless DC motor and flywheel models to simulate the FESS response. Relative to the input solar energy input of 4.68 kWh, the daily energy stored in a flywheel was 3.51 kWh, giving the overall solar-module-FESS system an efficiency of 74.7%. After the experimental setup completion of FESS, the integrated solar module-FESS model will be tested for its overall power output and efficiency against the traditional solar module-battery-system.

On the methodology of energy yield assessment for one-Sun tandem solar cells

Roof mounted solar panels come in form of fixed panels, unable to adjust to sun's position during day and throughout the year. As an effect, the efficiency of such solution is usually dependent on the roof slope and position of the building in relation to sun's day arc during seasons. These problems can be bypassed in free standing solar installations by equipping solar panels with solar tracker installations. Thanks to solar tracking, solar panels can be dynamically positioned perpendicular to the sun position and gather energy more efficiently throughout the day. This article presents a possibility of creating a roof mounted solar tracking panel to increase its efficiency. A prototype of solar tracking panel with two axes of movement was designed with an intention of an easy adaptation to being mounted on sloped surfaces of building roofs. A reference stationary panel was used to compare the efficiency of both solutions. A 5-day study was carried out to determine if the proposed solution could provide any benefits. Based on the study, the authors made an attempt to draw a conclusion whether the design could considerably increase the solar energy output to be worth the extra spending associated with solar tracker installation.

This paper presents an experimental diagnosis on the power performance of a PV system in Hong Kong. The annual solar radiation received by the PV modules was simulated based on the recorded horizontal solar radiation. The theoretical annual energy output of this PV system was about 11,702 kWh/yr, which was higher than the actual energy output by 24.5%. In order to find out the reasons of the energy loss, an on-site inspection and testing was conducted. The shading and aging problems were found in the process of visual inspection. The shading problem can be further subdivided into edge-shading, pillar-shading and nameplate shading. To further understand and quantify the impact of different types of shadings on the power output performance, the I-V curves of a PV module were tested under different solar radiation. The testing results showed that the impact of different types of shadings on the power performance varied with the Sun position, solar radiation as well as the time. In general, the edge-shading effect reduced the energy output of PV system by 11%-15% the pillar-shading effect reduced the energy output by 15%-19%, and both effects of edge-shading and pillar-shading reduced the energy output of PV system by 18%-35%. Thus, the main reason that resulted in the energy loss of this PV system was attributed to the shading impact. If the edge-shading and pillar-shading problems are solved, the annual energy output of the PV system could increase about 20%-24%.

A comprehensive numerical study on the effectiveness of a rotational-based PTC collector integrated porous foam and PV module

This paper reports the results of high-precision energy yield measurements of different PV module technologies performed at the headquarters of TUV Rheinland, Cologne, from May 2010 through April 2011. The investigations refer to 12 specimens each subjected to a separate electronic load for automated MPP tracking and V/Icurve measurements. Modules based on CdTe, CI(G)S, a-Si, a-Si/μ-Si, a-Si/a-Si and c-Si (mono and poly) semiconductors were analyzed and compared in a ranking with regard to the achieved specific energy yield. We consider the individual reasons for differences in performance, such as low irradiance behaviour, temperature coefficients, spectral irradiance effects and meta-instabilities of nominal power output, and describe the challenges in gathering high resolution measurement data.

Influence of Technological Changes on the Energy Yield of PV Modules: An Outdoor Study

This study aims to develop an IoT-integrated automatic dust cleaning device tailored for solar panels to enhance their performance and longevity. The cleaning process combines dry and wet cleaning techniques to effectively clean solar panels in a single line. First, dry cleaning methods such as brushes are used to remove loose debris like dust, leaves, and bird droppings. Then, wet cleaning is applied using a vinegar with mild detergent solution to remove stubborn stains and dirt buildup. This combination ensures thorough cleaning while minimizing water usage and environmental impact. The developed IoT-integrated automatic dust cleaning device effectively mitigates the negative impact of dust accumulation on solar panel performance. When compared to the characteristics of the clean module, the short circuit current (ISC) and output power of the photovoltaic solar modules with dust accumulation on their surface are reduced. For a day, a week, and a month of panel exposure to dust, the average deprivation rates of the solar modules' efficiency exposed to dust are 7.32%, 10.78%, and 14.52%, respectively. Experimental results demonstrate significant improvements in energy output and operational efficiency of in average of 12.37 %, following the implementation of this cleaning system. This system shows good solution to analyze the solar panel performance and to optimize it. This study presents a novel approach by integrating IoT technology into automatic dust cleaning devices for solar panels, enabling proactive maintenance and remote monitoring capabilities. It offers both dry and wet cleaning methods consequently for having optimized output. The innovative design contributing to the sustainability of solar energy systems with low cost for the users and provides remote accessing of data from anywhere in the world through cloud server. It is cost effective solution for the solar farm maintenance and helps in reducing the frequent manual interventions.

Investigating photovoltaic module performance using aluminium heat sink and forced cold-air circulation method in tropical climate conditions

Due the movement of the sun throughout the day, the insolation level incident on the fixed panel surface varies largely. The maximum level of insolation occurs only around noon. This leads to the panel to be under-utilised. To maximise the utilisation of the panel during the day, mechanical solar tracking is used. This method not only increases the utilisation of the, but increases the power being extracted from the panel. Solar tracking using one axis tracking increases the energy yield from the solar panel by 40 percent.Extended AbstractDuring the span of a day the sun's movement has been shown in figure 1. As the day passes by, the level of incident solar radiation (insolation) changes. This change takes place due to position of the sun. The angle at which the sun's rays fall on the photovoltaic panel affects the insolation level available for the panel to convert into electrical energy. For the fixed panel, the sun's rays are not normal to plane of the panel most of the time. This causes the panel to be under-utilised. To extract more energy from the same panel, solar tracking is required. This follows the sun's movement thereby increasing the insolation level throughout the day. This increase in the insolation level is due to the fact that the angle between the normal to the solar panel and incident light is to be kept minimum. Figure 1: Sun's movement throughout the day The principle of a single axis solar tracking has been shown in figure 2. The solar tracking can be accomplished by four methods: active tracking, passive tracking, chronological tracking and manual tracking [1]. Active trackers measure the light intensity from the sun using light sensors which give signal to the controller and driving mechanism. Passive trackers commonly make use of a low boiling point compressed gas. This gas is filled in two canisters each placed in east and west directions. The heating of the fluids cause the panel to tilt over to the side with more sunshine. These will have viscous dampers to prevent excessive motion in response to wind gusts [2]. A chronological tracker uses a rotation mechanism to counteract the effect of Earth's rotation. A simple rotation mechanism, turning at a constant speed of one revolution per day or 15 degrees per hour, is adequate for many purposes, such as keeping a photovoltaic panel pointing within a few degrees of the Sun. This can easily be achieved by the use of a stepper motor control. Figure 2: Principle of single axis solar tracking The data for the insolation level and temperature for the whole year have been obtained from the NASA website for Aligarh and Doha [3]. The simulations have been run assuming that there is no condition of partial shading. For the purpose of simulation of energy output during the day, five solar panels of 250 Wp were taken in parallel to give a total of 1.25 kWp of power under STC. The energy outputs for the months throughout the year were obtained for two conditions: first for the fixed panel condition, and second for the panel with continuous one-axis solar tracking. The results have been compared and shown for Aligarh and Doha in Figs. 3 and 4 respectively. In Fig. 5, the percentage increase in the energy output for each month has been shown for both the cities. Figure 3: Daily energy yield from a 1.25 kWp solar array on a monthly basis in Aligarh Figure 4: Daily energy yield from a 1.25 kWp solar array on a monthly basis in Doha Figure 5: Increase in daily energy yield on a monthly basisReferences[1] B H Khan ‘Non-Conventional Energy Resources’ Tata McGraw Hill, 2009.[2] Kamala J. and Alex J., 2014, ‘Solar Tracking for Maximum and Economic Energy Harvesting’, Int. J. of Engg. and Tech, Vol. 5(6), pp 5030–5037.[3] NASA Surface meteorology and Solar Energy website: https://eosweb.larc.nasa.gov

Perovskite on silicon tandem technologies offer a promising way to overcome the efficiency limit of single-junction crystalline silicon modules and are therefore widely studied. Besides the cost reduction potential of using tandem modules in utility-scale PV plants, the application of bifacial PV modules offers additional opportunities to reduce costs by increasing the energy yield. However, the bifaciality factor of tandem PV modules using bifacial crystalline silicon solar cells is typically lower than that of single-junction bifacial modules, considering the asymmetric architecture of the module with higher front-side than rear-side efficiency. In this study, we assess a symmetrical bifacial triple-junction perovskite/silicon/perovskite PV module architecture which allows for a significant improvement of the PV module rear side efficiency. Cost of ownership, energy yield and levelized cost of energy modeling show the superior performance of such modules compared to crystalline silicon and perovskite/silicon tandem modules specifically in vertical mounting applications that are used e.g.in AgriPV or noise protection PV walls on highways.

For commercial one-sun solar modules, up to 80% of the incoming sunlight may be dissipated as heat, potentially raising the temperature 20 C - 30 C higher than the ambient. In the long term, extreme self-heating erodes efficiency and shortens lifetime, thereby dramatically reducing the total energy output. Therefore, it is critically important to develop effective and practical (and preferably passive) cooling methods to reduce operating temperature of PV modules. In this paper, we explore two fundamental (but often overlooked) origins of PV self-heating, namely, sub-bandgap absorption and imperfect thermal radiation. The analysis suggests that we redesign the optical properties of the solar module to eliminate parasitic absorption (selective-spectral cooling) and enhance thermal emission (radiative cooling). Our Comprehensive opto-electro-thermal simulation shows that the proposed techniques would cool the one-sun and low-concentrated terrestrial solar modules up to 10 C and 20 C, respectively. This self-cooling would substantially extend the lifetime for solar modules, with The corresponding increase in energy yields and reduced LCOE.

A domestic water heating system that combines photovoltaic thermal (PVT) solar collectors with two heat pumps, in a novel cascade arrangement, is presented and analyzed in this paper. The goal of this analysis is to determine and compare the annual thermal energy output of the PVT cascade heat pump system with an evacuated tube and simultaneous consumption PVT single heat pump water heating system. The computational technique that was developed to analyze the PVT cascade heat pump system, which determines solar panel energy outputs, and heat pump operating characteristics, is described in detail. Case study simulation results are also presented, which include transient power output profiles, temperature profiles, and yearly energy output results. Hourly weather data, including air dry-bulb temperatures and solar flux values, from locations with a range of climates was used in these simulations. The results of this study show that the PVT cascade heat pump system has an annual thermal energy output improvement over the evacuated tube heating system ranging from 37% to 68%, depending on the selected simulation location.

Sun intensity and angle on efficiency of solar cell System is considered to study. Solar energy is a clean, non-polluting and renewable resource; it uses the photovoltaic effect to convert sunlight into a free and available energy source. However, solar energy output is highly affected by the temperature and intensity of sunlight. As the temperature of the solar module rises, energy output will decrease, if the intensity of sunlight is stronger, there will be more output energy. With adequate heat sink and proper ventilation, a module’s temperature will be decreased, and also increase output energy. This study uses 10 kilowatt grid-connected photovoltaic system and a solar tracker to measure the direction of the sun, to find out the relationship between solar intensity and angle effects on energy output.