Solar Penetration Research Articles

Probabilistic load flow based voltage stability assessment of solar power integration into power grids

The interconnection of renewable energies increases the complexity of modern power systems. Hence, stability assessments should be made to ensure the system’s stability after penetration. Solar power is a type of renewable energy that has become a widespread energy source among renewable energy sources. About 1 MWp of the solar power plant has been prepared to be interconnected to the IEEE 8 bus of Manokwari grid, and this paper investigates the voltage profile, power losses, and stability of the solar power plant penetration using an adaptive kernel density estimator (AKDE) and compares it to a Monte Carlo simulation (MCS)-based probabilistic load flow (PLF). About 5000 samples have been used to test the grid after the connection. Results of simulations show that the solar penetration can reduce power losses from 0.4084 MW to 0.3080 MW and 0.3045 MW by the proposed method and MCS method, respectively, and further increase the bus voltage profile. The power network has the stability to be connected to solar power, as indicated by the small stability index values of each bus. The proposed method using the AKDE method has a more accurate result in stability indices indicated by small fast voltage stability index (FVSI), line stability index (Lmn), and line stability factor (LQP) indices.

Transient response of a megawatt-scale solar photovoltaic in an electric distribution utility

There is an increasing trend among customers of an electrical distribution utility to adopt grid-tied solar photovoltaic systems. This shift offers multiple benefits to consumers, including lower monthly electricity bills and a contribution to the development of green energy. For the electrical distribution utility, various impacts may arise due to varying levels of solar energy penetration. This study investigates the effects of integrating varying levels of solar photovoltaic penetration into the commercial consumer network of Cagayan de Oro Electric Power and Light Company (CEPALCO) in the Philippines. Utilizing PowerWorld simulator, the research evaluates 11 different scenarios with solar penetration levels adjusted according to the percentage of load demand. Key findings include alterations in solar megavolt ampere of reactive power output, bus voltage levels, transformer power loading, and transmission line ampacity, with frequency levels remaining stable across scenarios. The optimal solar penetration level was identified at 70%, balancing the benefits of solar energy integration with the need to maintain grid stability and operational limits. This optimal level ensures the effective utilization of renewable energy sources without compromising the performance of CEPALCO’s electrical infrastructure. The research concludes with recommendations for maintaining grid stability and operational limits at the optimal solar penetration limits.

Solar surge and cost shifts: Heterogenous effects of redistribution in the electricity bills in Japan

This study investigates the impact of daily intermittency in solar energy on retail electricity bills, focusing on the “Duck Curve” and “Peak Shifting” phenomena and their varying effects on different consumer groups. Notably, commercial and industrial users exhibit higher demand around midday, while residential users peak during morning and evening hours. This prompts a crucial question: do peak shifting and redistribution effects differ among consumer groups due to their distinct electricity consumption patterns? Our analysis centers on Japan's power system, which has witnessed significant solar energy penetration, with solar capacity growing from 42 GW in 2016 to 83 GW in 2022. Utilizing monthly electricity consumption data and employing robustness checks through instrumental variable methods, we empirically demonstrate that increased solar penetration leads to higher electricity prices for residential consumers but reduced costs for commercial-industrial users. Additionally, we uncover the mediating role of pumped hydro storage (PHS) stations in stabilizing prices during peak and off-peak periods by managing energy demand variability, thereby mitigating economic impacts across consumer groups. This study highlights the issue of cross-class subsidization, where certain groups bear disproportionately higher electricity costs due to increased renewable energy penetration. It underscores the necessity for carefully crafted policy interventions to uphold market fairness and sustainability alongside large-scale renewable penetration, ensuring a balanced and equitable energy transition.

Renewable-battery hybrid power plants in congested electricity markets: Implications for plant configuration

Examining coupled renewable-battery power plants (“hybrids”) in congested areas provides insights into a future of increased wind and solar penetration. Our study focuses on two types of congested regions, Variable Renewable Energy (VRE)-rich Areas and Load Centers, and explores likely plant configuration choices for developers and transmission network planners. This paper examines how hybrid value, comprising energy and capacity value, varies by plant configuration and congested region type considering factors such as storage duration, battery degradation, and ability to charge from the grid. We select plant locations from across the seven main U.S. independent system operators (ISOs). Hybrid value for each configuration is computed based on profit-maximizing plant operation given perfect foresight, according to observed wholesale power market real time prices from 2018 to 2021. In VRE-rich Areas, the median increase in energy value from extending storage duration from one to 4 h is 29.4 % for solar and 26.8 % for wind, assuming low battery degradation costs and storage sized to 100 % of the plant's nameplate generation capacity. Increasing storage duration beyond 4 h does not substantially increase its value from energy markets, even in VRE-rich Areas. We find that solar hybrids reach a 90 % capacity credit with 4 h of storage, while wind hybrids require 8 h of storage, based on the capacity factor of each hybrid during the top 100 net load hours.

Effect of Generated Harmonics On Transformer Losses Due to Solar Penetration

Effect of Generated Harmonics On Transformer Losses Due to Solar Penetration

Integrating solar electricity into a fossil fueled system

The power sector is a major contributor to carbon emissions in China, accounting for nearly half of all emissions, and therefore emission reductions from this sector will be critical, if China is to meet its 2060 targets. Deploying renewable energy sources is the most promising approach to decarbonizing the power sector. However, the intermittency and non-dispatchable nature of wind and solar power pose significant challenges to grid stability, particularly when these sources reach high penetration rates. During China's ongoing energy transition, coal-fired power units will be used to meet peak loads when solar and wind generation is not available. The economic and environmental implications of such a scenario are unclear. In light of this uncertainty, this study applies a unit commitment model to investigate the economic and environmental performance of load shaving strategies across different scenarios. Results show that, in the absence of energy storage systems, a solar penetration rate of 40 % will create an economic bottleneck, and high solar penetration would even increase the total carbon emissions of the whole power system. Moreover, the power system would choose to cycle the large thermal units first to accommodate the solar power, and start-stop strategy is subordinate.

Financial Implications of Rooftop Solar Penetration in Sri Lanka from Utility Point of View

Solar is one of the fast growing and economical renewable power generation sources. The intention of development of solar power generation is to promote clean energy while addressing the basic requirement of uninterrupted and reliable electricity supply.The Sri Lankan government decided to adopt a policy that would use subsidies to encourage the growth of solar PV-based electricity. As a result, the market developed with a large number of customers eager to install solar rooftop systems, and they received strong assistance from solar power service providers. Hence, the utility is required to absorb the solar energy produced and this study focuses on the impact of solar penetration to the utility.System dispatch data for year 2019 and rooftop solar generation data for a period of 6 months of year 2019 were considered for the analysis in this paper. The model compares the financials of two scenarios to estimate the impact to the utility. The base case scenario, which is business as usual with the already installed solar generation in the system and No solar scenario which assumes that there is no solar in the system and therefore the demand is met by other available generation capacities in the system.This paper examines the two scenarios with careful calculations of how the system can still run without solar in the system. Daily demand patterns were also analysed and then expanded to months and summarized for the year. This research focuses the financial impact of solar electricity penetration to the national grid and how everyone can still be benefitted.

Comparative imaging of septic navicular osteomyelitis caused by a solar penetration injury in a 15‐day‐old Shire foal

SummaryA 15‐day‐old female Shire foal presented for acute lameness after sustaining a solar penetration injury, due to a nail, to the right hind sole 4 days previously. The foal was moderately lame at walk; all vital parameters were within normal limits. Clinical examination of the foot found a 2 mm long slit‐like defect in the plantar third of the lateral body of the frog. Radiographs revealed an ill‐defined rounded radiolucency within the navicular spongiosa that was surrounded by a halo of increased radiopacity. Transcuneal ultrasound corroborated the findings and found the navicular bone lesion to be closely associated with a hypoechogenic region within the lateral lobe of the deep digital flexor tendon (DDFT) all of which was continuous with a hypoechogenic tract extending from the sole. Computed tomographic examination confirmed a tract extending from the solar surface into the lateral portion of the navicular bone and confirmed a suspected impacted bone fragment. A diagnosis of septic navicular osteomyelitis and bursitis was made. The tract, navicular bone and DDFT were surgically debrided and navicular bursa lavage performed. The foal initially recovered well but navicular bursal sepsis recurred 6 days post‐operatively and the foal was euthanised. This report provides comprehensive comparative imaging of septic navicular osteomyelitis and bursitis secondary to a solar penetration in a 15‐day‐old foal and highlights the importance of different imaging modalities in case assessment and management.

Influence of the solar penetration depth and heat-fluxes on the sea surface temperature using an ocean mixed layer model

Solar penetration depth is a major factor in modulating the Sea Surface Temperature (SST) and hence influences the air-sea interface processes. This study investigates the influence of solar penetration depth and heat-fluxes on the SST at three RAMA (Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction) buoy locations (along 90°E at 15°N, 12°N, and 8°N) in the Bay of Bengal (BoB) using the One-Dimensional Price-Weller-Pinkel (1D-PWP) model. The results show that SST has strong dependence on the solar penetration depths with the shortwave component of solar insolation outweighing its longwave component. We found that spatio-temporally varying penetration depths refine the simulated SST, when compared against constant penetration depths. These spatio-temporally varying penetration depths (ranging from 10 to 75 m for the shortwave component; with higher values during monsoon) can be attributed to spatio-temporally changing biological parameters, wind, precipitation, and suspended particulate matter. Upon examination, an antiphase relationship between the penetration depths and total chlorophyll, total primary production, & total phytoplankton was found. Upon including the effect of horizontal advection and vertical entrainment in the 1D-PWP model results, the SST predictions improved albeit by a small amount. Furthermore, the effects of increased heat-fluxes, under the different Representative Concentration Pathway (RCP) equivalent scenarios, coupled with varying penetration depths were estimated. It was found that for the spatio-temporally varying penetration depths, the mean (maximum) increment was 0.52 °C (0.92 °C) under the highest emission scenario, i.e., RCP8.5, across all the locations. The results of the study can potentially be used further for 3D ocean modeling studies, and the characterization of air-sea interaction during monsoon and cyclones in the BoB.

Oxygen Storage Incorporated Into Net Power and the Allam–Fetvedt Oxy-Fuel sCO2 Power Cycle—Techno-Economic Analysis

Abstract With the planned future reliance on variable renewable energy, the ability to store energy for prolonged time periods will be required to reduce the disruption of market fluctuations. This paper presents a method to analyze a hybrid liquid-oxygen (LOx) storage/direct-fired supercritical carbon dioxide (sCO2) power cycle and optimize the economic performance over a diverse range of scenarios. The system utilizes a modified version of the NET Power process to produce energy when energy demand exceeds the supply while displacing much of the cost of the air separation unit (ASU) energy requirements through cryogenic storage of oxygen. The model uses marginal cost of energy data to determine the optimal times to charge and discharge the system over a given scenario. The model then applies ramp rates and other time-dependent factors to generate an economic model for the system without storage considerations. The size of the storage system is then applied to create a realistic model of the plant operation. From the real plant operation model, the amount of energy charged and discharged, the capital expenditures (CAPEX) of each system, energy costs and revenue and other parameters can be calculated. The economic parameters are then combined to calculate the net present value (NPV) of the system for the given scenario. The model was then run through the SMPSO genetic algorithm in Python for a variety of geographic regions and large-scale scenarios (high solar penetration) to maximize the NPV based on multiple parameters for each subsystem. The LOx storage requirements will also be discussed.

Estimation of Solar Power Generation Through the Use of Effective Forecasting Algorithms

The unpredictable nature of solar power generation poses significant challenges to energy management, particularly in power grids with high solar penetration, leading to potential imbalances between supply and demand. This has increased interest in developing accurate forecasting methods for photovoltaic power generation. This study focuses on short-term forecasting of solar power generation using MATLAB, based on historical generation trends through three different hybrid models. It uses a multilayer perceptron neural network as the forecasting tool, which is optimized through various algorithms to fine-tune the network's hyperparameters, such as the weights and biases of the input and hidden layers, for optimal performance. The Root Mean Square Error is used as the objective metric to minimize the discrepancy between actual and predicted values. The models use Particle Swarm Optimization (PSO), Imperialistic Competitive Algorithm, and Genetic Algorithm for network optimization. This research analyzes PV generation data from Belgium in July and August 2022, taken at 15-minute intervals, and evaluates model performance using six different error metrics, including Mean Absolute Error. The results show the accuracy and reliability in forecasting solar power generation time series.

Photovoltaic-penetrated power distribution networks’ resiliency-oriented day-ahead scheduling equipped with power-to-hydrogen systems: A risk-driven decision framework

Hydrogen energy and the pioneering power-to-hydrogen (P-2-H) systems have garnered significant interest due to their potential to revolutionize power systems, offering exceptional long-term energy storage capabilities and augmenting the resilience and flexibility of the grid. This paper presents a novel approach for optimizing the day-ahead proactive scheduling of power distribution networks with high solar penetration. The approach utilizes power-to-hydrogen (P-2-H) technology to enhance resiliency and mitigate risks. Uncertainties in solar irradiation, wind speed, electricity demands, and day-ahead market prices are modeled using a scenario-based probabilistic procedure. The optimization problem is formulated as a mixed-integer linear program that minimizes the network's expected normal and resiliency costs while incorporating downside risk constraints. The approach is applied to an IEEE 33-bus power distribution network, demonstrating the effectiveness of P-2-H facilities and risk assessment in improving resiliency during normal and power outage scenarios. Implementing P-2-H facilities in circumstances with and without risk results in a reduction of total operation costs by 40.89% and 40.32%, respectively, according to the simulation findings. Furthermore, the numerical analysis results show that the network's overall operation cost increase for achieving zero risk is only 3.93%, which reduces to 2.32% with the use of P-2-H facilities.

Research on distributionally robust energy storage capacity allocation for output fluctuations in high permeability wind and solar distribution networks.

This paper presents a novel approach to addressing the challenges associated with energy storage capacity allocation in high-permeability wind and solar distribution networks. The proposed method is a two-phase distributed robust energy storage capacity allocation method, which aims to regulate the stochasticity and volatility of net energy output. Firstly, an energy storage capacity allocation model is established, which considers energy storage's investment and operation costs to minimize the total cost. Then, a two-stage distributed robust energy storage capacity allocation model is established with the confidence set of uncertainty probability distribution constrained by 1-norm and ∞-norm. Finally, a Column and Constraint Generation (C&CG) algorithm is used to solve the problem. The validity of the proposed energy storage capacity allocation model is confirmed by examining different wind and solar penetration levels. Furthermore, the model's superiority is demonstrated by comparing it with deterministic and robust models.

The Impact of Solar Distributed Generation on Distribution Networks: Case Study of Chipata Distribution Network

The installation of solar PV systems in distribution networks is slowly increasing. The study focused on identifying the challenges and benefits of installing Distributed Solar Generation in the Chipata 33kV and 11kV distribution Networks. Chipata Town is in the Eastern Part of Zambia, and it has a peak demand of about 23.3MW. The 2023 version Power Factory Dig Silent Software was used to model the Chipata 33kV and 11kV distribution network and different Solar penetration levels were used to understand the impact of Distributed Solar. Chipata Distribution Network has four major stations operating at 33kV and 11kV voltages and four main distribution lines. The main objective of the study was to determine the impact of distributed solar PV in the Chipata Distribution Network. One of the specific objectives was to determine the hosting capacity of the Chipata Distribution Network. The hosting capacity gives the maximum amount of PV power integrated in a power system network without violating the set operation limits. The study analysed the impact of solar Distributed Generation on network losses, fault levels, voltage stability and line loading. The study revealed that an increase in penetration level resulted in a general increase in the Bus Bar voltages on both 11kV and 33kV voltage levels. Different Penetration levels of solar ranging from 6.66MW to 132MW were studied. Simulations revealed that the hosting capacity for Chipata Distribution Network is 96MW (412% of Solar PV Penetration Level). The voltages in the distribution network at hosting capacity were ranged from 0.93p.u to 1.02p.u. Short Circuit analysis simulations showed negligible impact on the fault level after integration of solar in the distribution network. Some circuits showed both increased and reduced power losses with increased solar penetration. The obtained results indicated that increased installation of distributed Solar PV systems in the Distribution Network impacts voltage stability, line losses and line loading.

From Double Skin Facade to Closed Cavity Façade with Triple Glazed Unite as Inner Skin Without Coatings in the Tropical Climate of Malaysia

The Close Cavity Façade (CCF) has undergone significant advancements from its predecessor, the Double Skin Façade (DSF), resulting in improved thermal insulation and reduced solar penetration. The core principle behind a CCF is a hermetically sealed and non-ventilated construction that incorporates an automatic shading system, triple glazing (TGU) on the inner surface, and single glass on the outer surface. The technique described above effectively regulates the ingress of solar energy and natural light into the building. The experimentation involved the utilisation of various combinations of CCF-TGU designs, employing software tools such as Window 7.8, EnergyPlus, and DesignBuilder. Then, a comparison analysis was undertaken to compare the aforementioned designs with the presently employed single-glazed units (SGU) featuring a grey coating. The inquiry was initiated through the implementation of a case study carried out on a condominium located on Penang Island, Malaysia. The CCF-TGU has superior thermal performance and provides enhanced occupant comfort when compared to SGUs. The effectiveness of CCF-TGU designs in reducing operating temperature ratios has been observed to be higher in Malaysia's humid tropical climate than that of SGUs. The annual rate of decrease varies between 29.8% and 77.8%, thereby successfully attaining the required level of thermal comfort. The research highlights the potential advantages of implementing an innovative CCF technology that has been modified to accommodate the distinct meteorological conditions of Malaysia. The findings suggest that the implementation of advanced glazing technology holds the potential to enhance both operational temperatures and overall occupant comfort within buildings.

A Control for Preventing False Tripping of Grid-Tied Renewable Systems With Increased Solar Penetration and Fluctuating Load Demand

A Control for Preventing False Tripping of Grid-Tied Renewable Systems With Increased Solar Penetration and Fluctuating Load Demand

Implications of Growing Wind and Solar Penetration in Retail Electricity Markets with Gradual Demand Response

Time-of-use pricing in retail electricity markets implies that wholesale market scarcity becomes easily communicated to end consumers. Yet, it is not well-understood if and how the price formation process in retail electricity markets will help to reward the demand for operational flexibility due to growth in intermittent generation. To contribute to this discussion, this paper develops a partial equilibrium model of the retail electricity market calibrated to Chinese data. The paper finds that tariffs in this market may not be significantly suppressed by growth in near-zero costs renewable sources when controlling for flexibility restrictions on thermal generation assets and when a significant curtailment of variable renewable resources exists in the market. In addition, it shows that the price formation process in retail electricity markets which controls for flexibility restrictions on thermal generation while allowing for consumers to respond slowly to price changes is a feasible strategy to reward the demand for operational flexibility. Finally, the paper reveals that while integrating intermittent generation beyond levels which the available storage capacities can accommodate may result in losses to producers, benefits to consumers may offset these losses, leading to overall welfare gains.

Meteorological drivers of resource adequacy failures in current and high renewable Western U.S. power systems

Power system resource adequacy (RA), or its ability to continually balance energy supply and demand, underpins human and economic health. How meteorology affects RA and RA failures, particularly with increasing penetrations of renewables, is poorly understood. We characterize large-scale circulation patterns that drive RA failures in the Western U.S. at increasing wind and solar penetrations by integrating power system and synoptic meteorology methods. At up to 60% renewable penetration and across analyzed weather years, three high pressure patterns drive nearly all RA failures. The highest pressure anomaly is the dominant driver, accounting for 20-100% of risk hours and 43-100% of cumulative risk at 60% renewable penetration. The three high pressure patterns exhibit positive surface temperature anomalies, mixed surface solar radiation anomalies, and negative wind speed anomalies across our region, which collectively increase demand and decrease supply. Our characterized meteorological drivers align with meteorology during the California 2020 rolling blackouts, indicating continued vulnerability of power systems to these impactful weather patterns as renewables grow.

Towards Sustainable Indoor Thermal Comfort in the Tropical Building Design: Comparative Performance Analysis of Fixed External Shading Elements and Differential Window Glass Thermal Properties

Tropical region is characterised by high outdoor solar radiation and temperature. These radiations penetrate into the interior particularly through the window glazing, thereby raising the indoor temperature with a resultant effect on high cooling energy demand (for comfortable indoor living condition). Of the identified three sustainable approaches towards inhibiting direct incoming indoor solar penetration in the tropical city of Ogbomoso, Nigeria, this study, through computer-based simulation technique, compared performance effectiveness of varying design interventions on the window composition/material adopted. Through multiple/iterative building performance simulation tool, DesignBuilder, the methodology involves virtual model of a three-bedroom residential building, typical of the prevailing building typology in the study area. This particular model served as the experimental control model. Three (3) variants of the control model, each with either externally mounted shading devices on the building envelope, or improved thermally resistant multilayer window glazing (i.e., double glazing) or low-emissivity coated window glazing material, were generated for individual performance effectiveness evaluation. All the four models were subjected to a twelve-month simulation cycle, to experience a year-round thermal conditions and evaluations individually. The results show that double-glazing window installation proved to be the most effective approach, with about 13.1 % improvement (i.e., solar radiation inhibition) on the indoor thermal gains. This is followed by the externally mounted shading devices (i.e., 11.1 % improvement) and the least inhibition (i.e., 5.0 %) was observed in the case of low-emissivity coated window glazing material. Adoption of double or more layers of glass panes in window fabrication for controlling indoor solar radiation penetration is therefore advised. Alternatively, integration of external window shading elements could be adopted. This study is directed towards reduction of cooling energy consumption in tropical buildings through efficient and sustainable indoor cooling mechanism capable of inhibiting solar gains into the building, with a focus on the performance roles and composition of windows in particular.

A Comprehensive Review: Mitigating Techniques for Power Variability Due to Integration of Renewable Energy Sources With Grid

Renewable energy sources like solar panels and wind turbines are becoming more important for generating power. The inconsistent and unreliable output of solar panels and wind turbines is due to factors like clouds, weather conditions, and wind speed that cause their energy production to fluctuate. Connecting intermittent sources to the utility grid creates difficulties in different technical areas, such as ensuring a steady and reliable power supply, protecting the system from disruptions, controlling the distribution of generated power, and maintaining a consistent level of power quality. In this situation, adjusting the amount of electricity produced by an intermittent energy source to keep the power grid stable is essential. This issue must be resolved as soon as possible. The extension to these locations diminishes the grid's strength. It leads to a scenario where a solar power plant is integrated into a subpar electric grid. However, integrating solar power into a shoddy AC infrastructure has problems with power quality (PQ) problems, which restricts penetration levels. This review article suggests various FACTS devices and various conventional, adaptive, and AI-based algorithms to reduce PQ issues brought on by a weak grid and increase renewable energy source (RES) penetration levels. This paper discusses the PQ issues that occur when RES like solar power plants (SPP) and wind power plants (WPP) or both as hybrid are connected to the electrical grid. It also explores different ways to reduce the fluctuation in power output from the solar panels. It analyzes the numerous power quality issues that arise with solar penetration and PQ mitigation methods using several FACTS devices and control algorithms, including traditional control, adaptive control, and AI-based control algorithms. For the benefit of engineers and academics working in this field of study, various research publications have been carefully evaluated, organized, and placed on this paper for convenient reference. It also briefly discusses the plan for controlling battery storage system for solve this problem.