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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

LA100 Equity Strategies. Chapter 12: Distribution Grid Upgrades for Equitable Resilience and Solar, Storage, and Electric Vehicle Access

The LA100 Equity Strategies project integrates community guidance with robust research, modeling, and analysis to identify strategy options that can increase equitable outcomes in Los Angeles' clean energy transition. As Los Angeles transitions toward clean energy, existing distribution grid infrastructure will need to be updated and expanded to support reliable service during routine operations, enable interconnection with distributed energy resources and electrified loads, and provide access to energy-related services during disasters. This chapter focuses on equity in distribution grid upgrades, reliability, and resilience in Los Angeles. Specifically, NREL performed grid upgrade and resilience analyses using a detailed model of the distribution grid and income-differentiated household load profiles, electric vehicle (EV) adoption patterns, distributed solar adoption, and grid reliability to explore two key questions to inform how the City of Los Angeles can ensure a resilient and reliable distribution grid for all communities during the clean energy transition: Where can distribution system upgrades can be prioritized to enable equitable access to, and adoption of, clean energy technologies and how can Los Angeles provide equitable, resilient access to electricity-related services (e.g., health care, food) during disaster events like earthquakes and flooding? The electric distribution system is the "last mile" of the grid, linking the multistate bulk power system with customers; new loads, including EVs; and distributed energy resources, such as customer and community solar and storage. This analysis focuses on the 4.8-kilovolt (kV) system, including service transformers that represent the utility-side of the grid connection for most residential customers. Chapter 17 looks at the customer-side of the grid connection with a focus on electric panel upgrade needs. The transition toward clean energy can put additional stress on the distribution system from distributed energy resources and electrification - especially EVs and increased use of electricity for heating, cooling, cooking, and hot water. This stress, measured here as the number of equipment overloads and voltage violations, correlates strongly to grid reliability and therefore is used as a proxy for understanding additional upgrades needed and to help ensure equitable access to electrification and distributed energy resources. NREL also conducted community resilience analysis to examine customer-level access to both electricity and a larger range of services, such as hospitals and grocery stores during a disaster. This analysis explicitly considers equity to understand differences in current resilience and resilience strategies to effectively improve critical services access for all Angelenos. Research was guided by input from the community engagement process, and associated equity strategies are presented in alignment with that guidance.

14 SOLAR ENERGY↗
DOE OSTI2022

SEIN: Breaking Barriers Resilient Energy System Analysis [Slides]

The Solar Energy Innovation Network (SEIN) is a collaborative research program that supports multi-stakeholder teams in researching and sharing solutions to real-world challenges associated with solar energy adoption. The Breaking Barriers project was selected to participate in the Solar Energy Innovation Network, Round 2, and was led by Groundswell, a D.C.-based clean energy project developer. The Breaking Barriers team included Partnership for Southern Equity, Atlanta University Center campus facility managers and professors, the City of Atlanta's Neighborhood Planning Unit T, and Georgia Power Company. The project aimed to design and construct innovative urban energy resiliency hubs integrating microgrid technology, solar generation, and energy storage in Atlanta colleges and communities. The hubs will help these historically Black colleges and universities (HBCUs) and the energy-burdened broader community in West Atlanta be more resilient, in addition to informing new course curricula at Atlanta University Center campuses. With many possible options for the system's battery size, the Breaking Barriers team needed insight into the relationships between BESS size, economic performance, and resilience at Spelman College's Manley Center. These insights are crucial for entering procurement negotiations with project developers, establishing resilience capabilities that the HBCU campuses can plan around, and guiding the team's fundraising targets. This analysis includes estimates of PV and battery performance, costs, savings, and resilience for multiple battery sizes. In order to provide power during a grid outage, the resilient energy system also needs to be connected to the Manley Center in a safe and island-able manner (electrically isolated from the grid). Analysis of potential electrical configurations and estimated setup costs is key to successfully entering a required interconnection agreement with Georgia Power, as well as informing requests for engineering firms to construct the system. This analysis includes conceptual options and rough order of magnitude cost estimates for electrically interconnecting the resilient energy system to the Manley Center and the grid. The Breaking Barriers team used this analysis to select preferred system characteristics and design for the resilient energy system.

14 SOLAR ENERGY↗
DOE OSTI2025

Residential and Small Commercial Solar Photovoltaic and Storage Permitting, Inspection, and Interconnection Timelines: A Retrospective Review (2017-2023)

This report is part of the ongoing Solar Time-Based Residential Analytics and Cycle Time Estimator (SolarTRACE) project, led by the National Renewable Energy Laboratory (NREL). The SolarTRACE project utilizes time-stamped project-level data provided by installer-partners to assess nationwide and AHJ- and utility-level PI&I and other solar PV adoption timelines since 2017. Our dataset now covers 22% of residential solar and 33% of residential storage installs in the U.S. since 2017. This report provides an update to our previous 2022 report (Cruce et al., 2022b) and includes: updated 2017 2023 project timelines for residential rooftop solar PV up to 20kW; updated tracking of permitting process changes at nearly 4,000 AHJs nationwide; and first-ever reporting of timelines for residential PV+storage projects up to 20kW.

14 SOLAR ENERGY↗
DOE OSTI2024

Modeling Distributed Generation in California

In support of analysis for the biennial Integrated Energy Policy Report, the California Energy Commission and the National Renewable Energy Laboratory have partnered to study the growth of distributed energy resources in California. This study involves the use of National Renewable Energy Laboratory's Distributed Generation Market Demand model, available at https://www.nrel.gov/analysis/dgen/, to project statewide adoption of distributed photovoltaics and paired storage. Key outcomes of the collaboration include: • Improved representation of California building stock, load profiles, historical adoption, and tariffs, including the net billing tariff, in the dGen model; • Trained CEC staff members to use and adapt the dGen model for their specific needs; • Developed a methodology for representing emerging consumer segments to potentially adopt distributed energy resources, including low-income, multifamily, and renter-occupied buildings; • Forecasted solar photovoltaic and paired storage growth in California using a common set of modeling parameters. This report describes the multiyear effort, which includes a discussion of: • Methodology and data employed in adapting the Distributed Generation Market Demand model for California to forecast solar photovoltaic and storage statewide through 2040; • Steps taken to modify the base model to forecast solar photovoltaic adoption in emerging market segments such as multifamily or renter-occupied homes or both; • Future enhancements of the model.

14 SOLAR ENERGY↗
DOE OSTI2024

Nova Analysis (Final Technical Report)

As the adoption of solar plus storage technology is rapidly increasing, there is a need for a more wholistic view of homes adopting them. In homes, both energy efficiency (EE) upgrades and DERs provide value not just to the homeowner, but to utilities and even society at large through emissions. Traditionally, EE and DERs are separate sectors, which makes it difficult to understand the co-benefits of their adoption. To address this, we created a novel workflow of tools that allows for a complete analysis of both efficiency and DERs. We also looked at a suite of metrics designed to capture the different benefits provided to different stakeholders, demonstrated with multiple sets of field data. A final report demonstrates the potential of the simulation workflow by simulating hundreds of buildings spread across the U.S. and demonstrating how a variety of factors affect the optimal sizing of DERs along with several other key metrics including energy, utility bills, emissions, and average resilience hours.

14 SOLAR ENERGY↗
DOE OSTI2024

Advancing Small Business Solar Equity: Final Technical Insights Report

The Advancing Small Business Solar Equity: Final Technical Insights Report represents the culmination of two years of work in participation with Round 3 of the National Renewable Energy Laboratory's Solar Energy Innovation Network (SEIN). SEIN Round 3, titled "Equitable Solar in Underserved Communities," supported eight underserved communities across the United States in "exploring new approaches to the equitable adoption of solar energy in residential and commercial-scale settings" and in "confronting the solar barriers they face and unlocking the solar benefits most relevant to their own contexts" (National Renewable Energy Laboratory 2023). This project was one of four selected to support solar access for commercial entities in underserved communities. The research conducted for this report was done within the Minnesota Twin Cities geographic context, but certain findings and the proposed Solar Hub Network model may be found applicable nationally. Community-based organizations that serve small businesses, chambers of commerce, community development finance institutions and other community lenders, municipal governments, solar incentive providers, solar industry professionals, and others may find elements of this report useful.

14 SOLAR ENERGY↗
NASA NTRS1992

Map-based trigonometric parallaxes of open clusters. II - The Hyades: 51 Tauri

The trigonometric parallax, mass, and mass ratio of 51 Tauri, a binary member of the Hyades star cluster, are determined. The parallax solution, 19.4 mas with a standard error of 1.1 mas, is slightly greater than its generally accepted value and yields a cluster distance of 4.30 +/-2.0 pc or a distance modulus equivalent of 3.16 +/- 0.10 mag, in excellent agreement with recent photographic parallax results. The weighted mean of all trigonometric parallax determinations of the cluster is now 22.9 +/-0.6 mas or a modulus of 3.20 +/- 0.06 mag. The total mass of the 51 Tauri system was found to be 2.56 +/- 0.44 solar masses. Adopting a magnitude difference in line with the spectral types of the components yields individual masses of 1.61 +/- 0.28 and 0.95 +/- 0.18 solar masses. This result places the mass of both the A8 V primary and the G0 secondary stars within the errors of the measurement of the mass-luminosity relation established for solar-neighborhood main-sequence stars.

Gatewood, George↗
DOE OSTI2021

Quantifying Rooftop Solar Benefits: A State-Level Value of Solar Analysis for India

Analyses that quantify the costs and benefits associated with rooftop solar (RTS) adoption and operation can inform decision-makers in the development and evaluation of RTS policies. One such analysis is a Value of Solar (VOS) study, which quantifies select costs and benefits surrounding RTS based on the electricity system context. These studies can drive changes to existing policies towards fairer, more cost-reflective RTS compensation or alternatively can provide confidence for the decision-maker to stay the course and largely maintain existing policies. This report provides a VOS analysis for two states in India: Gujarat and Jharkhand and provides details related to the methodology and key findings.

14 SOLAR ENERGY↗
NASA NTRS1976

Public policy for solar heating and cooling

Recent analyses indicated that solar heating and cooling systems for residential buildings are nearly economically competitive with conventional fossil fuel or electric systems, the former having higher initial cost but a lower operating cost than the latter. The paper examines obstacles to the widespread acceptance and use of solar space conditioning systems and explores some general policies which could help to overcome them. The discussion covers such institutional barriers limiting the adoption of solar technologies as existing building codes, financing constraints, and organizational structure of the building industry. The potential impact of financial incentives is analyzed. It is noted that a tax incentive of 25% could speed the use of solar energy by 7 to 8 years and produce an 8% reduction in fossil fuel use by 1990. A preliminary incentive package which could be helpful in promoting solar energy both at federal and state levels is proposed, and the necessary incentive level is analysed.

Hirshberg, A. S.↗
DOE OSTI2021

Enabling bifacial thin film devices by developing a back surface field using Cu x AlO y

Bifacial solar cells have the potential to increase the energy yield per unit area over traditional monofacial devices without significant added cost, driving $/kWh costs lower and accelerating the adoption of solar photovoltaics. However, the performance of bifacial thin film solar cells significantly lags that achieved by crystalline silicon cells. Here we incorporate wide bandgap Cu x AlO y as a back buffer layer for CdTe devices and achieve a backside illuminated device with high current density and high fill factor. Moreover, these values remain nearly constant even as the absorber layer thickness changes, indicating that a fully-depleted device is not required for efficient charge collection. We show that this response is indicative of a back surface field, albeit with a persistent high back surface recombination velocity. By managing electron reflection, we achieved a backside illumination conversion efficiency of 7.1% and bifaciality of 0.55 for a 3.3 µm CdTe device and 8.0% and 0.62 for a 2 µm device. Future improvements can be made by identifying and incorporating a passivation material that reduces the back surface recombination velocity.

36 MATERIALS SCIENCE↗
DOE OSTI2023

The electric vehicles-solar photovoltaics Nexus: Driving cross-sectoral adoption of sustainable technologies

Residential and transportation energy consumption account for more than one-half of the overall energy consumption in the United States. Adoption of electric vehicles (EVs) can play a key role in decarbonizing the transportation sector, while the adoption of renewable energy sources (e.g., solar photovoltaics [PVs]) could bring similar benefits to the residential energy sector and in turn support transport electrification. Although the market shares for both EVs and PVs continue to grow, both of these emerging technologies are deployed rather disjointly, without considering the existence of potential similarities among users who own (or aspire to own) these technologies. This might be due to lack of understanding of the behavioral interdependence in consumer preferences toward these technologies. To fill this gap in knowledge, this study utilizes data from the 2018 WholeTraveler Transportation Behavior Study to develop an integrated model system that explores interactive EV and PV adoption behaviors. A structural equation model is employed that incorporates direct effects as well as error correlations among the adoption behaviors for EVs and PVs. Model results indicate that the adoption behavior for both these technologies is indeed interconnected and significantly influenced by attitudes, values, and personality traits. Findings from this research suggest that incentives (e.g., subsidies) that drive bundled adoption of EV-PV systems could accelerate the adoption of both of these sustainable technologies. In conclusion, this study highlights the need to consider transport and building energy-efficient technology adoption behavior in a single integrated structure.

14 SOLAR ENERGY↗
DOE OSTI2023

The geographies, typologies, and trends of community-based organizations for solar energy in the United States

Community-based organizations (CBOs)1 play an important role in developing solar energy in low- and moderate-income (LMI) communities. This article shares the perspectives of CBO leaders in LMI communities, identifies and addresses solar information gaps, and provides recommendations State Energy Agencies and other government leaders can use to better involve CBOs in solar program initiatives. Using semi-structured interviews and focus groups with CBOs from across the United States (US) we develop typologies of CBO structure and function, and determine the primary motivations, challenges, opportunities, and communication barriers CBOs face. We explore the correlation between key typologies such as tenure, staff capacity, population served, organizational structure, and region with the organizational activities performed by solar-related CBOs. CBOs operate in disparate regional political and economic ecologies. Our findings suggest strategies for states to support their engagement in solar-related endeavors, particularly with respect to the dissemination of the Bipartisan Infrastructure Law, Inflation Reduction Act, and the EPA Greenhouse Gas Reduction Fund: Solar for All. Developing policies that encourage CBOs to enter the solar training and installation domains, alongside targeted grants and capacity-building initiatives can help maximize community benefits. Furthermore, states can additionally contribute to the positive trajectory and collaboration between state agencies and CBOs in advancing solar energy adoption by fostering a supportive environment.

14 SOLAR ENERGY↗
DOE OSTI2023

Addressing Regulatory Challenges to Tribal Solar Deployment (Abbreviated Final Technical Report)

Tribal land in the United States represents approximately 2% of the country’s total landmass and holds more than 5% of the solar photovoltaic potential (Doris, Lopez, and Beckley 2013). Though many Tribes have explored options to install solar photovoltaic (PV) generation capacity on their land, regulatory hurdles have often prevented them from doing so. The National Renewable Energy Laboratory (NREL) and the Midwest Tribal Energy Resources Association (MTERA) partnered on this 3-year project, Addressing Regulatory Challenges to Tribal Solar Deployment. The project sought to unlock Tribal solar potential by bringing together Tribal, regulatory, utility, and other stakeholders to articulate key barriers to Tribal solar PV adoption and develop replicable solutions.

14 SOLAR ENERGY↗
DOE OSTI2024

Vouchers to Enable Laboratory and Organizational Collaboration for Innovation and Technology Improvements (VELOCITI) Round 6 (Abstract)

For the past several years, the National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), and Pacific Northwest National Laboratory (PNNL) have provided technical assistance to the recipients of Department of Energy (DOE)-funded voucher programs, namely American-Made Challenges (AMC), the Incubator Program, and the Small Business Vouchers Program. Drawing on lessons learned and from first-hand experiences, NREL is leading a new holistic and streamlined voucher program aimed at strengthening ties between American innovators and the national labs. This new program, “Vouchers to Enable Laboratory and Organizational Collaboration for Innovation and Technology Improvements,” or VELOCITI, will leverage the successful elements of past programs, create administrative efficiencies, and enable the buildout of a national program to drive strong relationships between entrepreneurs and the national labs to accelerate the roll-out of new technologies in the US solar sector. This work will develop a comprehensive techno-economic assessment to understand the potential of repurposed batteries to achieve the DOE’s target of 5 cents per kWh Levelized Cost of Storage (LCOS), thereby facilitating the more affordable and widespread adoption of solar energy.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2026

Solar Thermal Energy Planner (STEP 1): A New Decision Support Tool for Solar Industrial Process Heat Applications

Solar thermal technologies are a promising technology to supply low-cost thermal energy to industrial processes, but there are often significant barriers to entry to industrial owners considering these technologies for their energy demands. To overcome this barrier and convey economic value to customers, NREL and Sandia National Laboratories developed Solar Thermal Energy Planner (STEP 1), a new web-based decision support tool for solar industrial process heat systems. At SolarPACES 2024, the STEP 1 tool was still under development; progress, methodologies, and a preliminary case study was presented. With the STEP 1 tool launch in May 2025, in this work, the initial version of the full public tool will be presented with demonstrations of its capabilities using a few case studies. First, the user's process heat needs such as location, process media (e.g., steam, air), process temperature, land availability, electricity and fuel costs, among other parameters. STEP 1 features a mapping interface that allows users to draw land and roof boundaries. The process media and temperature inform technology selection criteria modules that determine the appropriate solar thermal collection technologies, as well as congruent heat transfer media (e.g., hot water, oil, salt). Once the solar thermal technology selected, its nominal thermal production for the given site is characterized using NREL's System Advisor Model (SAM). Then, a modified version of NREL's REopt optimal sizing and dispatch optimization tool determines cost-optimal sizing. Within minutes, the user receives the results of the technoeconomics analysis, including the size and performance of the cost-optimal solar-plus-storage system. The cost of the system is compared to business-as-usual (e.g., an existing, standalone natural gas boiler). Users can download key results to store for sensitivity analyses. Examples of flat plate collector, parabolic trough, and molten salt tower applications with and without PV hybridization for different industrial facility types are presented in this work. The STEP 1 tool aims to reduce barriers to the adoption of solar heating solutions stemming from a lack of familiarity and technical background with solar system design options and costs among industry stakeholders.

14 SOLAR ENERGY↗
DOE OSTI2026

Integrating agrivoltaics into smallholder farming systems to enhance food production and irrigation efficiency under climate stress

Smallholder agricultural growers and entrepreneurs (SAGE) have a crucial role in sustaining food security; their cultivation accounts for roughly 30% of global crop production and contributes substantially to the diversity and nutritional value of food systems. Despite their awareness of and flexibility to adapt to productivity challenges, SAGE communities remain highly vulnerable to heat and drought stress, which threatens both livelihoods and local food availability. While intensification and adaptive farm practices offer partial resilience, their capacity to buffer sudden climatic extremes remains limited. Agrivoltaics, the dual use of land for solar electricity generation and crop cultivation, has emerged as a promising strategy to enhance agricultural productivity and its resilience to climate extremes by altering microclimatic conditions. Although proven effective in hot and arid regions, the benefits of agrivoltaics for temperate climates and small-scale farms remain minimally explored. To address this gap, we evaluated the performance of a small-scale agrivoltaics system in a temperate climate for high-value crops, including leafy vegetables and garlic. We investigate whether the system can (i) protect crops during extreme heat events and (ii) enhance productivity and reduce irrigation requirements during hot and dry periods unsuitable for conventional production. Our findings provide evidence that agrivoltaics is a climate-resilient farming strategy under current and projected climate scenarios, capable of improving yields (by +43% to +127% for the leafy vegetables grown) and reducing water consumption, while creating complementary economic opportunities through decentralized energy generation systems. This work supports the integration of agrivoltaics into small-scale agricultural systems as an innovative pathway to strengthen food security, bolster farmer livelihoods, and enable multiple co-benefits from broader solar energy adoption.

14 SOLAR ENERGY↗
DOE OSTI2023

Addressing Regulatory Burdens to Accessing Solar Among Municipal, Commercial and Institutional Customers Through Collaborative Partnerships (Final Technical Report)

The project focused on providing education to large energy customers, with a focus on local governments, to help them better understand and overcome barriers to solar energy adoption that currently exist (or could exist) in utility planning processes and/or within wholesale energy markets. The project team created accessible educational materials — ranging from reports to case studies to webinars — that could connect with stakeholders who rarely engage in these venues, have limited bandwidth to do so, and possess little previous knowledge of these issues. The project team focused on sharing lessons learned and best practices based on the experiences of other local governments and large energy users that have engaged on these issues, including the PJM Cities and Communities Coalition (PJMCCC). The project sought to better connect these customers and other stakeholders to deepen and expand opportunities for them to engage together on these issues, as well as build peer networks to facilitate the exchange of information. The project team held convenings of key partners — such as local governments, developers, regulators, utilities and large solar buyers — to discuss best practices, develop research products to broaden stakeholders’ knowledge base, and to foster these peer networks.

14 SOLAR ENERGY↗
DOE OSTI2022

Is the Adoption of Electric Vehicles (EVs) and Solar Photovoltaics (PVs) Interdependent or Independent? An Integrated EVs-PVs Modeling Framework

Transportation and residential energy consumption account for more than one-half of the overall energy consumption in the United States. Adoption of electric vehicles (EVs) can play a key role in decarbonizing the transportation sector, while the adoption of renewable energy sources (e.g., solar photovoltaics or PVs) could bring similar benefits to the residential energy sector and in turn support transport electrification. Although the market share for both EVs and PVs continue to grow, both these emerging technologies are deployed rather disjoint without considering the existence of potential similarities among users who own (or aspire to own) EVs and PVs. This might be due to lack of understanding of the behavioral interdependence in consumer preferences towards these technologies. To fill this gap in knowledge, this study utilizes data from the 2018 WholeTraveler Transportation Behavior Study to develop an integrated model system that explores EV and PV adoption behaviors. A structural equations model (SEM) is employed that incorporates direct effects as well as error correlations among the adoption behaviors for EVs and PVs. Model results indicate that the adoption behavior for both these technologies is indeed interconnected and significantly influenced by attitudes, values and personality traits. Findings from this research suggest that incentives (e.g., subsidies) that drive 'bundled' adoption of EVs and PVs could accelerate the adoption of both these sustainable technologies. The results highlights the need to consider transport and building energy efficient technology adoption behavior in a single integrated structure.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗