Solar Transition Research Articles

Scales of accountability: Solar mini-grids and clean energy for all in Uganda

There is great hope pinned on solar mini-grids to fulfil universal rural electrification targets and enable clean energy access, especially in low-income African countries such as Uganda. Yet Ugandan realities are complex, with many unelectrified households in villages the electric grid serves, and varied experiences with the few solar mini-grids implemented in recent years, indicating limited downward accountability. Crucially, large solar plants have arrived, making it timely to resolve the dilemma of just clean energy provision both in and from rural areas. Yet little research on energy transitions in this context exists to explain its political economic complexity. We draw on field visits to three solar mini-grids with contrasting performances, to Uganda's largest 20 MW solar plant, through dozens of villages, and on meetings with the regional utility and the Ministry of Energy and Mineral Development. This is supplemented by knowledge of Uganda's energy policy through document analysis and lived experience. We adapt accountability analysis to deploy a novel ‘scales of accountability’ framework at multiple spatial scales of solar deployment. Our analysis offers insights on the challenges Uganda must address to achieve the potential associated with solar mini-grids and multi-scalar solar energy transitions to achieve universal clean energy access.

There’s nothing more permanent than temporary solutions: the solar panel transition and everyday coping in Lebanon’s multi-dimensional crisis since 2020

What happens when a country, a population, or at least a segment thereof, navigates in a permanent state of crisis that becomes normalised into their everyday? Engaging with this question, this article analyses the evolution of Lebanon’s post-civil war electricity sector, with a particular focus on the on-going electricity crisis since 2020. We challenge perceptions of the temporary nature of crisis within much of the crisis literature and argue that processes of ‘everyday informality’ in the Lebanese context are structured by citizens’ assessment of effective service provision. This provides impetus for the contemplation of alternative forms of governance, often unfolding as coping mechanisms against adversities, that bypass and supplant state regulations in the energy sector in order to sustain the energy needs of individuals, households and businesses, manifesting informality in spite of the state.

CHIANTI—An Atomic Database for Emission Lines—Paper. XVIII. Version 11, Advanced Ionization Equilibrium Models: Density and Charge Transfer Effects

Version 11 of the chianti database and software package is presented. Advanced ionization equilibrium models have been added for low charge states of seven elements (C, N, O, Ne, Mg, Si, and S), and represent a significant improvement especially when modeling the solar transition region. The models include the effects of higher electron density and charge transfer on ionization and recombination rates. As an illustration of the difference these models make, a synthetic spectrum is calculated for an electron pressure of 7 × 1015 cm−3 K and compared with an active region observation from HRTS. Increases are seen in factors of 2–5 in the predicted radiances of the strongest lines in the UV from Si iv, C iv, and N v, compared to the previous modeling using the coronal approximation. Much better agreement (within 20%) with the observations is found for the majority of the lines. The new atomic models better equip both those who are studying the transition region and those who are interpreting the emission from higher-density astrophysical and laboratory plasma. In addition to the advanced models, several ion data sets have been added or updated, and data for the radiative recombination energy loss rate have been updated.

Modeling Transition Region Hot Loops on the Sun: The Necessity of Rapid, Complex Spatiotemporal Heating and Nonequilibrium Ionization

The study examines the heating profile of hot solar transition region loops, particularly focusing on transient brightenings observed in IRIS 1400 Å slit-jaw images. The findings challenge the adequacy of simplistic, singular heating mechanisms, revealing that the heating is temporally impulsive and requires a spatially complex profile with multiple heating scales. A forward-modeling code is utilized to generate synthetic Interface Region Imaging Spectrograph (IRIS) emission spectra of these loops based on HYDRAD model output, confirming that emitting ions are out of equilibrium. The modeling further indicates that density-dependent dielectronic recombination rates must be included to reproduce the observed line ratios. Collectively, this evidence substantiates that the loops are subject to impulsive heating and that the components of the transiently brightened plasma are driven far from thermal equilibrium. Heating events such as these are ubiquitous in the transition region, and the analysis described above provides a robust observational diagnostic tool for characterizing the plasma.

Transition magnetic moment of Majorana neutrinos in the triplets next-to-minimal MSSM

The next-to-minimal supersymmetric Standard Model with triplets is an attractive extension of the Standard Model. It combines the advantages of the next-to-minimal supersymmetric Standard Model and the minimal supersymmetric Standard Model with triplets to give three tiny Majorana neutrinos masses via a type-I+II seesaw mechanism. With the on-shell renormalization scheme, we consider the neutrino masses up to one loop approximation. Applying the effective Lagrangian method, we study the transition magnetic moments of Majorana neutrinos and consider the normal hierarchy and inverse hierarchy neutrino mass spectra within the constraints of experimental data on neutrino oscillations. The solar neutrino transition magnetic moment is further deduced, and compared with the XENONnT experiment limit. Published by the American Physical Society 2024

Filament eruption by multiple reconnections

Context. Filament eruption is a common phenomenon in solar activity, but the triggering mechanism is not well understood. Aims. We focus our study on a filament eruption located in a complex nest of three active regions close to a coronal hole. Methods. The filament eruption is observed at multiple wavelengths: by the Global Oscillation Network Group (GONG), the Solar Terrestrial Relations Observatory (STEREO), the Solar Upper Transition Region Imager (SUTRI), and the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). Thanks to high-temporal-resolution observations, we were able to analyze the evolution of the fine structure of the filament in detail. The filament changes direction during the eruption, which is followed by a halo coronal mass ejection detected by the Large Angle Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO). A Type III radio burst was also registered at the time of the eruption. To investigate the process of the eruption, we analyzed the magnetic topology of the filament region adopting a nonlinear force-free-field (NLFFF) extrapolation method and the polytropic global magnetohydrodynamic (MHD) modeling. We modeled the filament by embedding a twisted flux rope with the regularized Biot-Savart Laws (RBSL) method in the ambient magnetic field. Results. The extrapolation results show that magnetic reconnection occurs in a fan-spine configuration resulting in a circular flare ribbon. The global modeling of the corona demonstrates that there was an interaction between the filament and open field lines, causing a deflection of the filament in the direction of the observed CME eruption and dimming area. Conclusions. The modeling supports the following scenario: magnetic reconnection not only occurs with the filament itself (the flux rope) but also with the background magnetic field lines and open field lines of the coronal hole located to the east of the flux rope. This multiwavelength analysis indicates that the filament undergoes multiple magnetic reconnections on small and large scales with a drifting of the flux rope.

Predictive analysis of power degradation rate in solar PV systems emphasizing hot spots and visual effects-based failure modes

A definite and exclusive long-term PV degradation projection is required to reduce financial vulnerability in the solar photovoltaic plant-based energy transition markets. So, in this paper beside a traditional linear rate approach, a non-linear design tool for quantifying long-term failure mode-based power degradation rate (Rd), is proposed. An on-field experimental investigation incorporating visual effects-based Solar I–V characterization and thermal imaging for a duration of 1 year (February 2022 to January 2023) is carried out on a realistic solar PV system exposed to field conditions for 5–6 years. The experimentally evaluated Rd is 7.7 %/year. Two non-linear failure mode-based Rd models employing machine learning approaches, with differences in inputs are developed and are proven economically useable against the reported assessment techniques. The root mean square error (RMSE) for model 1 and model 2 during testing is 0.0019 and 0.0020 respectively (LSTM based approach) whereas testing error for model 1 and model 2 using back propagation based approach is 0.00182 and 0.00132 respectively. The proposed tool is also validated for a realistic PV plant in Telangana. A closeness of prediction against the actual of 9.0 % is observed for model 1 during validation, whereas the same for model 2 is 9.6 %.

Solar Energy in Indonesia: The Implementation of Sustainable Development Goals for Net Zero Emissions

Renewable energy transition from fossil to renewable energy is the focus of countries worldwide. Indonesia, as the largest country in ASEAN and has quite good economic growth, is also focusing on the issue of energy tourism. President Jokowi is trying to approach several countries with the same renewable energy commitment to realize Net Zero Emission (NZE). However, this research focuses more on solar energy related to the availability of sunlight in tropical climates such as Indonesia. Based on the concept used in this research, namely SDG pin 7, partnership in the field of solar energy continues to be carried out. The solar energy transition in Indonesia has yet to be fully realized. However, by 2026, it is hoped that it can be implemented despite several obstacles the government and stakeholders face. The method uses qualitative methods because the data is obtained from published scientific research on renewable energy and interviews with stakeholders. This research aims to continue to realize the transition from fossil energy to renewable energy to reach the NZE.

Upholding household agency in climate mitigation and socio-technical energy transition in Ethiopia

Despite major advances in global energy transition aimed at climate change mitigation, rural households in sub-Saharan Africa have yet to fully benefit from the increasingly accessible and affordable renewable energy sources. Whereas current literature focuses on conceptual frameworks and experiences of energy transition in developed countries, less is known regarding the household level implications of energy transition in the Global South. This paper investigates the socio-technical energy transition (STET) and adopts the muti-level perspective (MLP) to understand how different actors interact to achieve an equitable and sustainable energy transition in developing countries. Based on key informant interviews with stakeholders engaged in the solar energy transition in Ethiopia, we find that structural fragmentation across various levels and actors trickle down to affect household energy access and consumption. Despite enhanced access to clean energy offered by solar panels, the local users are often excluded from the dialogue surrounding renewable energy transition and climate mitigation, thus compromising their utilization of solar energy and the broader efforts to cut carbon emissions. This paper, therefore, calls for interactive governance and the creation of a decentralized communication platform that recognizes local energy consumers as pivotal agents of change.

A global solar transition could leave Africa in the shade

A global solar transition could leave Africa in the shade

The Non-Thermal Radio Emissions of the Solar Transition Region and the Proposal of an Observational Regime

The transition region is a very thin but most peculiar layer in the solar atmosphere located between the solar chromosphere and the corona. It is a key region for understanding coronal heating, solar eruption triggers, and the origin of solar winds. Here, almost all physical parameters (density, temperature, and magnetic fields) have the maximum gradient. Therefore, this region should be highly dynamic, including fast energy releasing and transporting, plasma heating, and particle accelerating. The physical processes can be categorized into two classes: thermal and non-thermal processes. Thermal processes can be observed at ultraviolet (UV) and extreme ultraviolet (EUV) wavelengths via multi-wavelength images. Non-thermal processes accelerate non-thermal electrons and produce radio emissions via the gyrosynchrotron mechanism resulting from the interaction between the non-thermal electrons and magnetic fields. The frequency range spans from several GHz to beyond 100 GHz, in great number of bursts with narrowband, millisecond lifetime, rapid frequency drifting rates, and being referred to as transition region small-scale microwave bursts (TR-SMBs). This work proposes a new type of Solar Ultra-wide Broadband Millimeter-wave Spectrometer (SUBMS) that can be used to observe TR-SMBs. From SUBMS observations, we can derive rich dynamic information about the transition region, such as information about non-thermal energy release and propagation, the flows of plasma and energetic particles, the magnetic fields and their variations, the generation and transportation of various waves, and the formation and evolution of the source regions of solar eruptions. Such an instrument can actually detect the non-thermal signals in the transition region during no flare as well as the eruptive high-energy processes during solar flares.

Green conversion of delignified sorghum straw and polyethylene glycol into form-stable phase change materials with promising solar energy capture, transition, and storage capabilities

Phase change materials (PCMs) have attracted considerable attention as a thermal energy management technology for thermal storage. However, achieving high energy-storing abilities, low leakage rates, and solar absorption abilities simultaneously in PCMs remains greatly challenging. This research proposed a green strategy for preparing sorghum straw-based PCMs. By facile delignification and solvothermal process, delignified sorghum straw (DSS) and carbon quantum dots (CQDs) derived from removal lignin are prepared. The obtained PEG@CQDs/DSS possessed considerable reusable stabilities, excellent photo-thermal conversion properties, and thermal energy management capacities due to the delicate micropores and intrinsic noncovalent interactions among components. Especially, the PEG@CQDs-7.5/DSS exhibited superior solar-thermal conversion capabilities (with conducive photo-thermal conversion efficiency ~90.84%), and kept stable after 100 cycles of heating and cooling, in which the melting enthalpy value is ~168.1 J/g (enthalpy efficiency of ~91.11%). In conclusion, the synthesized PCMs showed potential for application in energy-saving and building thermal management.

Detection of decayless oscillations in solar transition region loops

Context. Decayless kink oscillations have been frequently observed in coronal loops, serving as a valuable diagnostic tool for the coronal magnetic field. Such oscillations have never before been reported in low-lying loops of the transition region (TR). Aims. The aim of this study is to detect decayless kink oscillations in TR loops for the first time. Methods. We used the SI IV 1400 Å imaging data obtained from the Interface Region Imaging Spectrograph. We applied the Multiscale Gaussian Normalization method to highlight the TR loops, and generated time–distance maps to analyse the oscillation signals. Results. Seven oscillation events detected here exhibit a small but sustained displacement amplitude (0.04–0.10 Mm) for more than three cycles. Their periods range from 3 to 5 min. The phase speed is found to increase with loop length, which is consistent with the decrease in Alfvén speed with height. With these newly detected oscillations, we obtain a rough estimate of the magnetic field in the transition region, which is about 5–10 G. Conclusions. Our results further reveal the ubiquity of decayless kink oscillations in the solar atmosphere. These oscillations in TR loops have the potential to be a diagnostic tool for the TR magnetic field.

Gendered sociotechnical imaginaries: Understanding the role of masculinities in Portugal's pursuit of multi-scalar solar energy transitions

Solar energy advocates increasingly draw attention to solar PV technologies as a vehicle for achieving greater local autonomy, inclusivity, and democracy. A future energy system may take many forms, but with the current system being male-dominated, and gender being a central factor in shaping societal values, we argue that ideas derived from different forms of masculine value systems are likely to be reproduced in the solar PV rollout. Thus, it is necessary to ascertain how gender co-shapes sociotechnical imaginaries that are used to legitimize different transition pathways. In this study, we draw on data from fieldworks in Portugal between 2022 and 2023, including 50 semi-structured interviews. We find that Portugal has two major and different solar-specific imaginaries, each drawing on different forms of masculinities. Simultaneously, each competing imaginary perpetuates a different set of societal expectations related to the masculinity it represents, and along with this, legitimating different sets of expectations around public accountability, gender equality, democracy, and energy justice.

Internal Activities in a Solar Filament and Heating in Its Threads

Filaments are one of the most common features in the solar atmosphere and are of significance in solar, stellar, and laboratory plasma physics. Using data from the Chinese Hα Solar Explorer, the Solar Upper Transition Region Imager, and the Solar Dynamics Observatory, we report on multiwavelength imaging and spectral observations of the activation of a small filament. The filament activation produces several localized dynamic brightenings, which are probably produced by internal reconnections of the braided magnetic fields in the filament. The filament expands during the activation, and its threads reconnect with the ambient magnetic fields, which leads to the formation of hot arcades or loops overlying the filament. The thermal energy of each of these localized brightenings is estimated in the order of 1025–1027 erg, and the total energy is estimated to be ∼1.77 × 1028 erg. Our observations demonstrate that the internal magnetic reconnections in the filament can lead to localized heating in the filament threads and prompt external reconnections with ambient corona structures and thus could contribute to the energy and mass transferring into the corona.

Conflict and uneven development in the multidecade distributed solar energy transition in the United States.

A longitudinal analysis of small-scale solar energy generation in the United States is used to demonstrate how transition studies can explain nonlinearity in multidecade changes of consumption-production systems. Nonlinearity involves uneven development of sustainability innovations with episodes of rapid growth but also periods of slow growth, stalling, or even collapse. Factors that affect the increasing feasibility and attractiveness of small-scale solar include technological improvements, declining costs, and changes in global energy markets. However, a more complete explanation of nonlinearity highlights the importance of a type of systems analysis that also includes strategic action and broader societal and policy changes. Specifically, efforts by the utilities constrained the growth of small-scale solar by weakening policy support because of the perceived threat, but the solar industry and advocates responded with countervailing action in a changing context. As the transition developed, strategic action (including goals, targets, tactics, and coalition partners) changed and became more conflictual. However, by the beginning of the 2020 decade, the development of microgrids, digital technologies, storage, and virtual power plants in combination with net-zero energy policies provided indications of potential for a reconfiguration of the relationship that could be less polarized and conflicted.

Updated Reference Wavelengths for Si vii and Mg vii Lines in the 272–281 Å Range

New reference wavelengths for atomic transitions of Mg vii and Si vii in the 272–281 Å wavelength range are derived using measurements from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board the Hinode spacecraft. Mg vii and Si vii are important ions for measuring plasma properties in the solar transition region at around 0.6 MK. The six Si vii wavelengths are 13–21 mÅ and 7–11 mÅ longer than the values in the NIST Atomic Spectra Database (ASD) and the compilations of B. Edlén, respectively. The four Mg vii wavelengths are shorter than the values in the ASD by 8–12 mÅ but show reasonable agreement with the Edlén values. The new wavelengths will lead to more accurate Doppler shift measurements from the EIS instrument and will be valuable for spectral disambiguation modeling for the upcoming Multi-Slit Solar Explorer mission.

The Lomonossov arc: refraction and scattering in Venus atmosphere during solar transits

The main observations of 1761 by M. Lomonossov and those that followed are recalled by extending the discussion to other remarkable visual observations of the passages, then with more and more powerful imagers producing images in profusion. The modern treatment of parasitic effects is briefly recalled by focusing on the expert observation of 1761 which has recently been widely commented on and criticized. It included a spurious effect called the “black drop effect”. The shell or aureole or atmospheric ring of Venus observed outside the solar disk is considered with reference to the today parameters of the Venus atmosphere. The contacts during the transit are discussed taking into account effects of scattering, absorption, and the dominant effects of the refraction at the small angular distances found to be comparable to a fraction of the angular dimension of the planet. Modern observations of the 2004 and the 2012 transit are tentatively discussed to elucidate what is the arc of Lomonossov.

The momentum of the solar energy transition

Decarbonisation plans across the globe require zero-carbon energy sources to be widely deployed by 2050 or 2060. Solar energy is the most widely available energy resource on Earth, and its economic attractiveness is improving fast in a cycle of increasing investments. Here we use data-driven conditional technology and economic forecasting modelling to establish which zero carbon power sources could become dominant worldwide. We find that, due to technological trajectories set in motion by past policy, a global irreversible solar tipping point may have passed where solar energy gradually comes to dominate global electricity markets, without any further climate policies. Uncertainties arise, however, over grid stability in a renewables-dominated power system, the availability of sufficient finance in underdeveloped economies, the capacity of supply chains and political resistance from regions that lose employment. Policies resolving these barriers may be more effective than price instruments to accelerate the transition to clean energy.

Spectral Features of the Solar Transition Region and Chromospheric Lines at Flare Ribbons Observed with IRIS

We report on the spectral features of the Si iv λ1402.77, C ii λ1334.53, and Mg ii h or k lines, formed in the layers from the transition region to the chromosphere, in three two-ribbon flares (with X, M, and C class) observed with IRIS. All three lines show significant redshifts within the main flare ribbons, which mainly originate from the chromospheric condensation during the flares. The average redshift velocities of the Si iv line within the main ribbons are 56.6, 25.6, and 10.5 km s−1 for the X-, M-, and C-class flares, respectively, which show a decreasing tendency with the flare class. The C ii and Mg ii lines show a similar tendency but with smaller velocities compared to the Si iv line. Additionally, the Mg ii h or k line shows a blue-wing enhancement in the three flares, in particular at the flare ribbon fronts, which is supposed to be caused by an upflow in the upper chromosphere due to the heating of the atmosphere. Moreover, the Mg ii h or k line exhibits a central reversal at the flare ribbons but turns to pure emission shortly after 1–4 minutes. Correspondingly, the C ii line also shows a central reversal but in a smaller region. However, for the Si iv line, the central reversal is only found in the X-class flare. As usual, the central reversal of these lines can be caused by the opacity effect. This implies that, in addition to the optically thick lines (C ii and Mg ii lines), the Si iv line can become optically thick in a strong flare, which is likely related to the nonthermal electron beam heating.