High Direct Normal Irradiance Research Articles

Renewable Horizons: Solar Power and Dairy Industry in India

Renewable energy is energy obtained from sources that are essentially inexhaustible such as wind power, solar power, geothermal energy, tidal power, bio-energy and hydropower. It is also known as non-conventional energy. Harnessing renewable energy offers numerous environmental benefits, including mitigating climate change, reducing air pollution, conserving natural resources, and enhancing energy security by diversifying energy sources. Solar resources are available in every country and both Solar Photovoltaic (SPV) and Concentrating Solar Power (CSP) technologies can be used to convert solar resource into electricity. SPV can use both direct and diffuse sunlight to generate power, while CSP relies on direct sunlight, restricting its deployment to areas with high Direct Normal Irradiance (DNI). Mandatory demand supported with higher subsidies for green technologies will positively attracts dairies towards use of solar energy. In many villages, power cut hinders the reception of milk from milk producers as electronic weighing system and milk testing instruments require uninterrupted power supply. solar-powered dairy operations offer resilience against power outages and fluctuating energy costs, empowering farmers with greater control over their operations. As the Indian dairy industry embraces solar power, it not only secures a greener future but also fosters economic growth and energy access in rural communities, marking a significant stride towards sustainability and self-sufficiency.

A method for design optimization of roof-integrated two-stage solar concentrators (TSSCs)

The optimal performance of two-stage solar concentrators (TSSCs) as building-integrated energy solutions is achievable through an integrative design of TSSCs and the building geometry. Such a design process reflects a multi-criteria decision-making problem involving different stakeholders having domain-specific concerns. To support this, in this study, a method to perform a two-step, design optimization of building and TSSCs engineered concerning building geometry is presented by developing a parametric model and applying, a multi-objective optimization algorithm (NSGA-II). The method allows for the creation of different design solutions in several iterations using a population set of individuals (decision variables) related to building design (i.e., roof type and slope, building orientation, length, width, and building type), and TSSC design (type, geometric ratio, mirrors' separation distance, modules number, and receiver area). Thus in several iterations, the method enables finding optimal solutions i.e., building with maximum direct normal irradiance (DNI) and TSSCs with maximum average load match index (av.LMI), and minimum average covered roof area (av.CRA). The application of the method is shown in a case study of four different, hypothetical residential buildings under the climate settings of Berlin. These buildings are illustrative (descriptive), which depict theoretical volumes as abstract representations of future constructions. Thus, a set of simulation runs are performed according to different model settings, to enable early-stage design exploration of future/new constructions which differ in size (varying floor levels) and energy demand. Results indicate that most solutions reflect buildings of high DNI (more than 125 kW/m2/month) and TSSC of av.LMI from 0.4 to 4.2, and av.CRA from 8% to 47%. Nevertheless, the performance of TSSCs depends on the building type. The method enables a performance-driven design approach, searches for the most feasible solutions, and helps to meaningfully support the decision-making process.

Technical, economic and environmental analysis of solar thermochemical production of drop-in fuels

This study analyzes the technical performance, costs and life-cycle greenhouse gas (GHG) emissions of the production of various fuels using air-captured water and CO2, and concentrated solar energy as the source of high-temperature process heat. The solar thermochemical fuel production pathway utilizes a ceria-based redox cycle for splitting water and CO2 to syngas – a tailored mixture of H2 and CO – which in turn is further converted to liquid hydrocarbon fuels. The cycle is driven by concentrated solar heat and supplemented by a high-temperature thermal energy storage for round-the-clock continuous operation. The study examines three locations with high direct normal irradiation using a baseline heliostat field reflective area of 1 km2 for the production of six fuels, i.e. jet fuel and diesel via Fischer-Tropsch, methanol, gasoline via methanol, dimethyl ether, and hydrogen. Two scenarios are considered: near-term future by the year 2030 and long-term future beyond 2030.In the near-term future in Sierra Gorda (Chile), the minimum fuel selling price is estimated at around 76 €/GJ (2.5 €/L) for jet fuel and diesel, 65 €/GJ for methanol, gasoline (via methanol) and dimethyl ether (DME), and 42 €/GJ for hydrogen (excluding liquefaction). In the long-term future, with advancements in solar receiver, redox reactor, high-temperature heat recovery and direct air capture technologies, the industrial-scale plant could achieve a solar-to-fuel efficiency up to 13–19 %, depending on the target fuel, resulting in a minimum fuel selling price of 16–38 €/GJ (0.6–1.3 €/L) for jet fuel and diesel, and 14–32 €/GJ for methanol, gasoline, and DME, making these fuels synthesized from sunlight and air cost-competitive vis-à-vis e-fuels. To produce the same fuels in Tabernas (Spain) and Ouarzazate (Morocco) as in Sierra Gorda, the production cost would increase by 22–33 %. Greenhouse gas savings can be over 80 % already in the near-term future.

Which power cycle is the best fit for parabolic trough solar collectors? A comparative and comprehensive case study for six sub-configurations of the three main cycles

In this study, the integration of a Parabolic Trough Collector with different power cycles was investigated on an annual basis in terms of Energy, Exergy, Economics and Environmental under different meteorological conditions. A parabolic trough collector with 500 collectors with a gross and net aperture area of 432,000 and 817.43 m2, was installed in a place that has a high solar energy potential. With a Parabolic trough collector, hourly Direct Normal Irradiation, wind speed, wind direction, ambient temperature and incident angle values were obtained for the 15th of each month for a year. The performance of the 3 power cycles with 6 different configurations using the Parabolic trough collector as the heat source was comprehensively analyzed and compared. During the dynamic data use and various commonly used power systems comparing study, it was aimed to answer the most commonly asked questions by the researchers in this area. To do this, the effect of direct normal irradiation and incident angle on the performance of systems to reach the maximum net power was studied. After calculations, the maximum net power was not found on July 15 (12:00) when the maximum direct normal irradiation (840.868 W/m2) was seen. The maximum net power (67867 kW) was found on September 15 (12:00) when the incident angle was minimum (1.71°) along with the high direct normal irradiation. Steam Rankine Cycle, Organic Rankine Cycle and Kalina Cycle performance comparisons were made both annually depending on time and with different configurations and fluids. In addition to tangibly showing the superiority of incident angle on direct normal irradiation, the present study aimed to present the best-performing system configuration for the researcher, user, scientists, and manufacturers. Interestingly, while the Organic Rankine Cycle with heat exchanger with R123 showed better performance in terms of power production and carbon dioxide emission reduction, the Kalina Cycle was found much more feasible in terms of economics.

Thermal performance investigation of the newly shaped vacuum tubes of parabolic trough collector system

The parabolic trough collector (PTC) system is currently the most mature technology for concentrator solar power (CSP) plants. However, the huge radiative heat loss under high temperatures is one of the major obstacles restricting its thermal efficiency and development to the higher temperature. To reduce the radiative heat loss, this study proposes a newly shaped tube (NS-tube) with flatted upper and lower surfaces based on the Negative thermal-flux region theory. By considering different opening angles and tracking errors of the shaped tubes, an optical simulation is developed to analyze the heat flux distribution, and a heat transfer model is established to investigate the heat loss and thermal efficiency. Results show that the thermal efficiency of the NS-tube with optimum opening angles can be improved by 0.62%–4.64% compared to the original tube. The improvement effect is more obvious at high operating temperatures and low Direct Normal Irradiance. Additionally, the thermal stress variation is also analyzed by Ansys fluent. The result shows that the thermal stress of the NS-tube is even smaller than that of the original tube due to the uniform thermal flow effect caused by the flattened lower surface.

Exergoeconomic Analysis of an Integrated Solar Combined Cycle in the Al-Qayara Power Plant in Iraq

Enhancing the sustainability and diversification of Iraq’s electricity system is a strategic objective. Achieving this goal depends critically on increasing the use of renewable energy sources (RESs). The significance of developing solar-powered technologies becomes essential at this point. Iraq, similar to other places with high average direct normal irradiation, is a good location for concentrated solar thermal power (CSP) technology. This study aims to recover the waste heat from the gas turbine cycle (GTC) in the Al-Qayara power plant in Iraq and integrate it with a solar power tower. A thermoeconomic analysis has been done to support the installation of an integrated solar combined cycle (ISCC), which uses concentrated solar tower technology. The results indicate that the examined power plant has a total capacity of 561.5 MW, of which 130.4 MW is due to the waste heat recovery of G.T.s, and 68 MW. is from CSP. Due to the waste heat recovery of GTC, the thermal and exergy efficiencies increase by 10.99 and 10.61%, respectively, and the overall unit cost of production is 11.43 USD/MWh. For ISCC, the thermal and exergy efficiencies increase by 17.96 and 17.34%, respectively, and the overall unit cost of production is 12.39 USD/MWh. The integrated solar combined cycle’s lowest monthly capacity was about 539 MW in September, while its highest monthly capacity was approximately 574.6 MW in April.

A method for global potential assessment of roof integrated two-stage solar concentrators (TSSCs) at district scale

This paper proposes a core method for integrating two-stage solar concentrators (TSSCs) as roof-integrated energy supply systems at the district scale. However, the performance of these systems not only depends on good configurations but also on optimal building typologies. The design process of buildings-integrated TSSCs on a district scale reflects a complex multi-criteria problem, where several conflicting concerns from multiple stakeholders need to be addressed. Thus, the proposed method aims to support the multi-criteria decision-making process in the early-stage design of sustainable districts utilizing TSSC technology. The method contributes to the design of the TSSCs relative to district designs. Our method enables design generation according to a set of decision variables related to the district (roof type and slope, orientation, building height, width, and length), and TSSC (type, geometric ratio, separation distance between mirrors, modules number, and solar cell size). The method uses a parametric modeling approach combined with a multi-objective optimization algorithm (NSGA-II) that enables design optimization of the district and TSSCs in two consecutive steps. The two-step design optimization allows finding optimal district designs for maximizing cumulative direct normal irradiance (DNI) and minimizing the total energy demand, and TSSC designs for maximizing average monthly load match index (av.LMI) (a ratio of energy yield to demand) and minimizing the average covered roof area occupied by modules. We validated the proposed method in an illustrative case study of ‘Buckower Felder’, a district in the city of Berlin (Germany). The illustrative application shows that our method enables the performance-driven, generative design of both; district and building-integrated TSSCs and searches for the most appropriate solutions i.e., urban designs for maximum DNI and minimum demand, and TSSC designs for maximum av.LMI and minimum covered roof area. Results indicate that there is a trade-off between objectives, where district design with high DNI (>4500 kW/m2/h/month) reflects high energy demand (8.6e + 05 kWh/month). Similarly, TSSC designs ensuring high av.LMI (>1.0) require a large roof area (>47 %). Given these trade-offs, the method can meaningfully support the decision-making process. Thus, the method allows for large-scale integration of TSSCs with buildings at an urban scale and supports solar energy planning and energy transition policies for sustainable districts.

Collaborative optimization of thermal and economic performances of a tower solar aided coal-fired power generation system

• New operation strategy of solar aided coal-fired power generation unit is proposed. • The system annual performances in different solar irradiation levels are studied. • Collaborative optimization of the proposed system configurations is carried out. • Multi-time scale thermal performance analyses of the proposed system are conducted. • The sensitivity analyses of the economic parameters of solar field are explored. This paper studies a novel tower solar aided coal-fired power generation (TSACPG) system with thermal energy storage (TES) system to realize the high-grade solar energy cascade utilization and puts forward an improved annual operation strategy of the system. The variations of annual electricity output from solar, annual solar to electricity efficiency and solar field levelized cost of electricity (LCOE) of the proposed TSACPG system under different solar multiples and thermal energy storage hours are explored in different level direct normal irradiation (DNI) sites. Collaborative optimizations of the TSACPG system configurations are performed by the non-dominated sorting genetic algorithm-II. The results demonstrate that the annual electricity output from solar is positively correlated with yearly DNI level and ascends with the increases of both TES hour and solar multiple. The annual solar to electricity efficiency descends with an increasing solar multiple and ascends with an increasing TES hour. The solar field LCOE will initially descend with the increase of solar multiple to the minimum and then ascend, and it will also ascend with an increasing TES hour. The improved operation strategy proposed is superior to the simple operation strategy in terms of both thermodynamic and economic performances. The pareto fronts in different level DNI sites are obtained with the simultaneous optimization of the annual electricity output from solar and the solar field LCOE. The best compromise solutions are obtained. The optimal TES hours and solar multiple values in high, medium and low level DNI sites are 14.14 h/2.64, 14.22 h/2.61 and 12.15 h/2.52, respectively. The multi-time scale analyses of the TSACPG system in different level DNI sites are conducted. The results suggest that the electricity output from solar is relatively high and the solar to electricity efficiency is comparatively low in high level DNI sites. The daily performance result implies that the system has a better performance in high level DNI site, which provides an important reference for the actual design of the system. Economic analysis reveals that the tower solar system investment payback time shows the superiority in high level DNI site and the investment payback time exhibits a trend towards shortening with an increasing coal price. Meanwhile, the sensitivity results of economic performance indexes show that the TSACPG system economic performance is closely related to the price of system components, which exhibits the impact of market changes on economic benefits for decision makers.

Waveguide Concentrator Photovoltaic with Spectral Splitting for Dual Land Use

This research presents a highly transparent concentrator photovoltaic system with solar spectral splitting for dual land use applications. The system includes a freeform lens array and a planar waveguide. Sunlight is first concentrated by the lens array and then reaches a flat waveguide. The dichroic mirror with coated prisms is located at each focused area at the bottom of a planar waveguide to split the sunlight spectrum into two spectral bands. The red and blue light, in which photosynthesis occurs at its maximum, passes through the dichroic mirror and is used for agriculture. The remaining spectrums are reflected at the dichroic mirror with coated prisms and collected by the long solar cell attached at one end of the planar waveguide by total internal reflection. Meanwhile, most of the diffused sunlight is transmitted through the system to the ground for agriculture. The system was designed using the commercial optic simulation software LightTools™ (Synopsys Inc., Mountain View, CA, USA). The results show that the proposed system with 200× concentration can achieve optical efficiency above 82.1% for the transmission of blue and red light, 94.5% for diffused sunlight, which is used for agricultural, and 81.5% optical efficiency for planar waveguides used for power generation. This system is suitable for both high Direct Normal Irradiance (DNI) and low DNI areas to provide light for agriculture and electricity generation at the same time on the same land with high efficiency.

Selection of Optimal Locations for Electricity Generation Using Concentrated Solar Power Technologies in Ghana

The selection of an optimum location for the installation of a Concentrated Solar Power (CSP) plant is very vital to its overall performance. Any selected location should suitably satisfy some favourable selection criteria such as high direct normal irradiance, high ambient temperature, lower wind speed, lower level of cloud cover and availability of a source of water. In this paper, the selection of an optimal location(s) for a CSP plant in Ghana is achieved using the Analytical Hierarchy Process (AHP) for the weighting of the selected criteria and then using a set of Multi-Criteria Decision-Making (MCDM) methods for the ranking of the various alternatives. The MDCM methods used in this work include the Vise Kriterijumsa Optimizacija I Kompromisno Resenje (VIKOR), Technique for Order of Performance by Similarity to Ideal Solution (TOPSIS), and Complex Proportional Assessment (COPRAS). The results indicate that VIKOR and COPRAS gave very closely related rankings while some of the rankings for the COPRAS were not closely related as compared to the other two methods. However, all three methods ranked Bawku, a town in the Upper East region of Ghana, as the most suitable location for the installation of a CSP plant. The other suitable locations, i.e., Navrongo, Yendi, Wa, Bolgatanga and Savelugu, for the installation of a CSP plant are in the northern part of the country.

Multi-objective optimization of a Concentrating Solar Power + Photovoltaic + Multi-Effect Distillation plant: Understanding the impact of the solar irradiation and the plant location

• The impact of the location parameters in a CSP + PV + MED is analyzed. • Multi-objective optimization is performed to minimize thermoeconomic costs. • The irradiation and distance have the most significant impact on the costs. • Cost maps of the thermoeconomic cost of electricity and water are presented. This research work presents the assessment of the impact of the solar irradiation, the distance from the coast, and the altitude of the location for a Concentrated Solar Power + Photovoltaic + Multi-Effect Distillation (CSP + PV + MED) plant for simultaneous power generation and seawater desalination. For that, a comparative analysis of the thermoeconomic cost of electricity and water (TCE and TCW) at different locations is carried out to determine the most competitive sites where this kind of cogeneration plant can be deployed. Also, multi-objective optimization is performed to assess the optimum sizing that allows reducing the costs. The study considers four Direct Normal Irradiation (DNI) levels (from 2000 to 3500 kWh/m 2 -yr), six distances from the sea (from 5 to 100 km), and six altitudes (from 20 to 1000 m.a.s.l.). The results show that solar irradiation has the most significant effect on the TCE and TCW, the distance to the sea affects the TCW considerably, and the altitude has a moderate impact despite its impact is substantially lower than the other two factors. Also, cost maps of the TCE and TCW giving insights about which locations have a higher potential for developing CSP + PV + MED plants are presented. From these maps, it has been found that the potential inland locations to reach TCE and TCW under 100 $/MWh and TCW 2 $/m 3 should have high DNI (at least 300 kWh/m 2 -yr above the coast level), distances from the coast up to 60 km, and altitudes up to 750–1000 m.

Evaluating the Market Potential of Concentrated Solar Thermal Technology for Different Applications in the MENA Region

Abstract Missing financial and regulatory frameworks lead to low development and stagnating costs of concentrated solar thermal technology. Nevertheless, in locations with high direct normal irradiance (DNI) such as the Middle East and Northern Africa (MENA) region, the technology could become competitive, being promised a learning rate of 10–20%, and boost local economies. This study aims to identify potential business cases and evaluate the increased technology's investment likelihood in the region, focusing on Egypt. A thorough market assessment on the structure, regulatory framework, demand, and potential revenues was conducted for the power and process heating sector. A SWOT analysis was performed considering the local context and competing technologies. Egypt was shown to offer local manufacturing potential, regulatory framework, and renewable energy (RE) strategies, facilitating the technology's deployment. Moreover, the market is already open for private investment and selected international funds are directed toward CSP development. High initial technology cost, subsidized fuel and electricity prices for industry, alongside lack of long-term financial incentives and awareness of potential long-term benefits for the economy were identified as the most significant threats. High solar heat demand for industrial processes and large potential for concentrated solar heat (CSH) application were identified. Yet, the market is decentralized and the processes are very diverse, moreover retrofitting may pose risks alongside the high upfront investment and additional land costs, which makes concentrated solar heat applications less attractive for the Egyptian industrial sector. Hence, for concentrated solar technology deployment, financial incentives and a regulatory framework specifically directed toward the technology would be necessary.

Efficiency enhancement of a solar trough collector by combining solar and hot mirrors

Parabolic trough collector is an up-and-coming technology for urban energy supply. To further enhance the optical-thermal efficiency of the collector, a modified receiver enhanced by solar and hot mirrors was proposed. In this receiver, two symmetrical solar mirrors were designed to collect more solar irradiance, and a transparent hot-mirror shield was employed to lessen the thermal loss. After the design, the collector performance was studied by developing an optical-thermal coupled model. Based on the model, firstly, the proposed receiver was compared with the conventional receiver and two existing modified receivers. Results indicate the proposed receiver can achieve an optical efficiency of 78.02%, which is higher than those of the existing modified receivers and is just 0.22% lower than that of the conventional one. Moreover, compared with the conventional receiver, the two existing modified receivers cannot improve the optical-thermal efficiency at sufficiently high direct normal irradiance or relatively low fluid temperature, which can be overcome by the proposed receiver. Furthermore, compared with the conventional receiver, the proposed receiver can lessen the thermal loss by 11.2–89.6 W·m−1, thus improving the receiver efficiency and the optical-thermal efficiency by 0.03–5.26% and 0.03–4.70%, respectively, under the typical ranges of the inlet temperature (573–823 K) and the direct normal irradiance (0.3–1 kW·m−2). Then, parameter analysis indicates the hot mirror with low emissivity is necessary for efficiently improving the optical-thermal efficiency. Finally, the proposed receiver can improve the optical-thermal efficiency more effectively at higher fluid temperature or larger coating emissivity. The above results signify that the proposed receiver can be helpful for enhancing the efficiency of the trough collector.

Environmental Impact of the High Concentrator Photovoltaic Thermal 2000x System

High Concentrator Photovoltaic Thermal (HCPV/T) systems produce both electrical and thermal energy and they are efficient in areas with high Direct Normal Irradiance (DNI). This paper estimates the lifecycle environmental impact of the HCPV/T 2000x system for both electrical and thermal functionalities. Process-based attributional method following the guidelines and framework of ISO 14044/40 was used to conduct the Life Cycle Assessment (LCA). The midpoint and endpoint impact categories were studied. It was found that the main hotspots are the production of the thermal energy system contributing with 50% and 55%, respectively, followed by the production of the tracking system with 29% and 32% and the operation and maintenance with 13% and 7%. The main contributor to the lifecycle environmental impact category indicators was found to be the raw materials acquisition/production and manufacturing of the thermal energy and tracking systems. The results indicate that the lifecycle environmental impact of the HCPV/T 2000x system is lower compared to fuel-based Combined Heat and Power (CHP) and non-Renewable Energy Sources (non-RES) systems.

Anti-soiling coating performance assessment on the reduction of soiling effect in second-surface solar mirror

Soiling represents a major problem for CSP plants, since the accumulation of particles onto the reflective surface cause absorption and scattering of solar irradiance, leading to a significant decrease in the mirrors’ reflectance. Such problem can be amplified, particularly in CSP plants that are installed in semi-arid or arid regions which possess a high direct normal irradiance availability, prone to higher particle deposition due to sand storms, red rain events and, in general, higher atmospheric particle concentration. As means to reduce the amount of dust adhering to the mirrors, anti-soiling coatings are being developed to reduce particle deposition, minimizing maintenance costs due to cleaning processes, leading to an enhancement of energy production. In this paper, a Tracking Cleanliness Sensor was used to compare the Soiling Index between a set of coated and uncoated mirrors, which were left outdoors to naturally accumulate soiling in two different positions, horizontal and tilted 45°. The anti-soiling coating was developed by a partnership between RIOGLASS and IK4-TEKNIKER. Moreover, a simple economical model is proposed here for different possible scenarios regarding the coating used.

Techno-Economic and Life Cycle Analysis of Energy Generation Using Concentrated Solar Power (CSP) Technology in Sokoto State. Nigeria

: In this work a predictive performance simulation of Solar Tower, Linear Fresnel and Parabolic Trough Concentrating Solar Power (CSP) plants was undertaken for Sokoto State in Northwestern Nigeria. The State was selected based on its high Direct Normal Irradiation (DNI) values and long hours of sunshine per day relative to other places in Nigeria. The simulation was done using System Advisor Model (SAM) Software. In the study, 50 MW, 75 MW and 100 MW for each of the three CSP technologies were considered and their Techno-economic and Life Cycle analyses were carried out. The results showed that Solar Tower plant is more favored to be adopted for use in the studied site because it has the highest annual electrical energy generation, higher capacity factor and lowest Levelised cost of Electricity. The Net Present Values of the CSP plants at the site are (with the exception of the 50 MW Linear Fresnel CSP using hybrid cooling) positive implying that the project is economically viable. The study also showed that at solar multiple of 2, the Levelised costs of Electricity for both Solar Towers and Parabolic Troughs were the lowest, irrespective of the cooling system (wet or dry cooling). Solar multiple has no effect on the water usage irrespective of the CSP plant. Dry cooling system reduces the water usage by 86% and 95% for Solar Tower and Parabolic Trough plants, respectively. Dry cooling system reduces the annual electrical energy generation in the range of 7.3 to 7.5 percent for Solar Tower plant and 8 to 9 percent for Parabolic Trough plant. The largest environmental impact was human toxicity at 25,400 g 1,4-DB eq. and the least is marine ecotoxicity at 1.33 × 10-4 g 1,4-DB eq.Keywords: Annual Generation; Debt Fraction; Human toxicity; Freshwater Eutrophication

Model and Validation of Single-Axis Tracking With Bifacial PV

Single-axis tracking is a cost-effective deployment strategy for large-scale ground-mount photovoltaic systems in regions with high direct-normal irradiance. Bifacial modules in 1-axis-tracking systems boost energy yield by 4%–15% depending on module type and ground albedo, with a global average of 9%. This benefit is in addition to the 15%–25% energy gain already afforded by single-axis tracking relative to fixed-tilt deployments. Here, we compare model results against field performance data for two side-by-side bifacial/monofacial tracked systems—one in Albuquerque, NM, USA, and one in eastern Oregon. The Albuquerque system shows monthly rear irradiance gain of 10%–14.9%, and the Oregon bifacial system has an average performance ratio 9.4% higher than the monofacial system. Both results match bifacial irradiance model results within uncertainty. Simulations show that smart tracking algorithms can offer more than 1% improvement on annual energy yield by adjusting tilt angle under cloudy conditions. Finally, ray-tracing simulations investigated edge brightening, suggesting a 15%–25% increase in rear irradiance at the ends of tracker rows, but up to 20% loss from center-mounted torque tubes, creating multiple shadows.

Comparative energy and greenhouse gas assessment of industrial rooftop-integrated PV and solar thermal collectors

Solar technologies are a clean source of energy with no emissions during their usage phase, however, not all solar technologies are created equal in terms of their total impacts over their life-cycle. While many life-cycle assessment (LCA) studies have investigated solar photovoltaics and—to a lesser extent—solar thermal technologies independently, there are very few direct comparisons between these technologies due to differences in their design/sizing, boundaries, location-specific performance, and several other factors. However, since electricity can be converted to heat (and visa-versa), it is clearly possible to make such a link to holistically compare different solar technologies with respect to an intended application. To address this, the following article provides an LCA methodology to comparatively assess the environmental impact of solar thermal (ST) and solar photovoltaic (PV) technologies from cradle through the usage phase (noting that end-of-life impacts for these systems are still uncertain). That is, characteristic collector types which could be employed on factory and commercial rooftops were evaluated based on their embodied energy payback time (EPBT) and greenhouse gas emission payback times (GHGe PBT). Characteristic geographical locations were also analyzed since the equivalent carbon dioxide impact can vary between regions and these technologies due to differences in the available solar resource and the primary energy mix, they offset. This research also presents new data and an original assessment for a linear Fresnel collector which is suitable for industrial rooftops. The analysis revealed that the EPBT and GHGe PBT varied between 1.2 and 15 years and between 2 and 17 years, respectively, for the solar technologies and geographical locations considered in this study. The results also indicate that an ST collector system has a lower EPBT in high direct normal irradiation locations than a monocrystalline PV system. However, in terms of the GHGe PBT, the findings do not reveal a conclusive verdict for or against ST versus PV technologies. Overall, this study provides a new, global comparison between ST and PV solar technologies for industrial applications. This work is significant since many manufacturers around the world are considering utilizing their factory rooftop space for solar energy harvesting. As such, the proposed LCA method provides guidance for manufacturers, policymakers, and future sustainability reporting standards, to determine which solar technology achieves the fastest EPBT and GHGe PBT if the local solar resources and primary energy mix are known.

Annual performance analysis and optimization of a solar tower aided coal-fired power plant

The integration of solar energy into coal-fired power plants has been proven as a potential approach in the utilization of solar energy to reduce coal consumption. Moreover, solar augmentation offers low cost and low risk alternatives to stand-alone solar thermal power plants. In this study, the annual performance of a solar tower aided coal-fired power (STACP) system is investigated, and the influence of thermal storage system capacity on the annual solar generating power and annual solar-to-electricity efficiency is explored. The thermal storage system capacity is optimized to obtain the lowest levelized cost of electricity (LCOE). At the same time, the influence and sensitivity of several important economic factors are explored and assessed. Results demonstrate that compared to a coal-fired power system, the reduction in the annual average coal consumption rate of the STACP system with high direct normal irradiance (DNI), medium DNI, and low DNI are 5.79, 4.52, and 3.22 g/kWh, respectively. At a minimum, the annual coal consumption can be reduced by 14,000 t in a 600 MWe power generation unit. Because the same solar field is considered under different DNI conditions, the LCOE in the high DNI, medium DNI, and low DNI scenarios are all fairly similar (6.37, 6.40, and 6.41 ¢/kWh, respectively). When the solar multiple is 3.0, the optimal thermal storage capacity of the STACP system, with high, medium, and low DNIs are 6.73, 4.42, and 2.21 h, respectively. The sensitivity analysis shows that the change in economic parameters exerts more influence on the STACP system with the high DNI compared with the other two scenarios.

Optimum sizing of the inverter for maximizing the energy yield in state-of-the-art high-concentrator photovoltaic systems

The sizing of the inverter in comparison to the rated capacity of the photovoltaic generator is investigated for high-concentrator photovoltaic (HCPV) systems. An HCPV module of typical characteristics is modelled and parameterized, taking into account direct normal irradiance (DNI), ambient temperature, air mass and aerosol optical depth as atmospheric inputs, while the DC losses of the HCPV generator are allowed to vary in the ranges reported in the literature. A set of 80 commercial inverters are analysed to obtain the typical efficiency curves of state-of-the-art low-, medium-, and high-efficiency inverters. Four locations worldwide with high annual DNI levels and different average values of the weather variables influencing HCPV performance are studied. Results show that the inverter can be sized between 84% and 112% of the rated capacity of the HCPV generator at Concentrator Standard Test Conditions depending on the scenario considered for maximizing the final energy yield of the system. The proposed methodology uses analytical equations, all the model parameters are provided and justified and atmospheric inputs are obtained from meteorological databases in order to make the application easy regarding its use in other locations where the climate data is available.