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At least 829 records · Page 46

Bifacial PV System Mismatch Loss Estimation & Parameterization

Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.

14 SOLAR ENERGY↗

Bifacial PV System Mismatch Loss Estimation and Parameterization: Preprint

Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several scenarios including horizontal single-axis tracking (HSAT) and rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for HSAT systems and high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.

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Buried Ducts: A Cost-Effective Technical Solution to High Performance Homes

Traditionally, attics have been insulated at the flat ceiling with deliberate venting to manage heat and moisture. Having all the duct air distribution system in the conditioned space is the best building science approach, however this is not always the preferable solution for builders that like to use the roof space for air distribution. Ducts in attics are exposed to very intense heating and cooling conditions. Not only do we have thermal conduction, convection and radiation exchanges occurring but important duct leakage losses that create significant energy balance losses. In the recent IECC 2018 code, deeply buried attics have been credited for reducing the energy losses. Due to the complex thermal performance in each zone adjacent to the buried ductwork these credits seem to be not consistent with the benefits achieve by buring the ductwork in insulation. The thermal performance of buried ducts was examined in both 2-D and 3-D to determine the actual improvement as a function of duct size, duct insulation and attic insulation. In this paper we will describe the field/laboratory and modeling effort undertaken by to quantify the performances of duct systems. Climate zone 2A is included in the field testing, that encompass both hot/dry climates and hot and humid climates. Attics with deeply buried ducts and low air duct leakage had excellent thermal performance and exhibited the best overall thermal performances. Indeed, based on the thermal simulation analysis of deep buried ducts the thermal performance is better than the credit given to them by IRC 2018 code.

Salonvaara, Mikael↗

Installing Hotel Rooftop Solar Array

This case study describes how a luxury hotel, Bardessono, utilized a major roof-top solar array in its design to achieve significant energy savings and LEED Platinum certification.

LEED, LEED Platinum, rooftop array, solar, solar p↗

Rooftop Unit Replacement: Target's Rooftop Unit Replacement Program

This case study describes how Target developed an optimized, re-engineered process that integrates several energy-efficiency measures such as reduced lighting loads, improved roof insulation, optimized ventilation, and more accurate load calculations through its rooftop unit (RTU) replacement program. Target's approach achieved ongoing energy reduction, operations and maintenance reduction, and improved heating, ventilating, and air-conditioning (HVAC) performance by reducing equipment cycling.

HVAC, Rooftop Unit, RTU, commercial, retail, air c↗

Implementing Solar - Leased Retail Building

This case study describes a multi-site solar photovoltaic (PV) installation project undertaken by BJ’s Wholesale Club. It describes how BJ’s worked with their landlords to overcome the split incentive of the installation, ongoing operational requirements, roof maintenance, and vacancy/turnover at several locations in Massachusetts, Maryland, and New Jersey.

Commercial, retail, leased, solar, solar photovolt↗

Raising the Bar in High Performance Laboratory Design

Laboratory facilities are expensive to build and operate, they consume energy at high rates compared to other types of buildings, and modifications are frequently required to accommodate ever-changing research activities. PNNL sought ways to address these issues in the design and construction of a 14,700 sq. ft. new laboratory building. To improve adaptability to change a high roof structure was used that allows raising the ceiling when needed with minimal disruption to installed HVAC and electrical utilities. Also, HVAC equipment was located on a mezzanine above the central corridor rather than above ceilings. This eliminates the need for maintenance personnel to routinely access lab spaces, reducing disruption to research staff and improving maintenance access. To improve the reliability of operations while reducing energy consumption, heat pipe heat recovery with evaporative cooling, zoned heating/cooling coils, high-efficiency condensing boilers, district cooling, VAV fume hoods, DDC controls, energy use monitoring, and implementation of the US Department of Energy’s Guiding Principles for Federal Leadership in Sustainable Buildings were all used. The energy model developed during design projected energy use at 2,840 MBtu/yr, a 13.5% savings over ASHRAE Standard 90.1-2010. The first full year of operation resulted in actual energy use of 2,661 MBtu, a savings of 19% over Standard 90.1. As a result of the project design’s demonstrated success, these strategies will be incorporated into a significantly larger (125,000 sq ft), $65 million lab facility to be constructed on the PNNL campus in 2020.

Scott, Jeffery M.↗

Scaling Equitable Finance

Driven by dramatic declines in up-front cost, the U.S. solar photovoltaics (PV) industry has taken off over the past decade, growing from 1 gigawatt of installed capacity in 2009 to 89 gigawatts in 2020—or enough capacity to power roughly 19 million homes. The industry is expected to double in size over just the next 5 years.1 Much of the growth has been driven by large, utility-scale projects that can produce 5 mega- watts or more of power—enough to power at least 1,000 homes. The cost of electricity produced by these projects has decreased by more than 70 percent since 2010. As of Q3 2020, development costs of large, util- ity-scale solar PV power plants were under $1 per watt, down by more than 70 percent from 2010.2 A robust array of investors has come forward to efficiently deliver capital to these kinds of utility-scale projects including large banks, insurance companies, pension funds, and others. But low- and moderate-income communities, including communities of color, are at risk of being left behind in the transition to clean energy. Mission- driven solar project developers and financial institu- tions have been working alongside energy justice advocates to open up solar access for these communi- ties, using strategies ranging from community solar, to solar installations on affordable multifamily housing, to distributed solar and storage programs, and more. Their goals go beyond simply generating more green energy to advancing social equity by: • empowering communities to control their energy future • stabilizing energy prices, saving money, and build- ing wealth for low-income families • creating quality jobs • improving health by reducing pollution • providing energy resilience for vulnerable communities Mission-driven actors are successfully deploying a wide variety of strategies to meet these goals, from helping low-income homeowners get solar—and some- times battery storage, to developing solar projects serv- ing affordable rental housing and community facilities, to building larger “shared solar” projects to which households from across the community can subscribe. However, the financing ecosystem does not work nearly as well for these “mission driven” solar proj- ects as it does for utility-scale projects. For home rooftop solar, even if low-income consumers have a home and suitable roof, they may fail to qualify for federal tax incentives, lack adequate credit to qualify for a loan—or the mission-driven lenders seeking to serve them may not be adequately capitalized to make long-term loans. For mission-driven commercial or community-scale projects, assembling nearly every component of the project capital stack—whether bridging early-stage costs, attracting tax credit equity investors, securing long-term debt, or coming up with sponsor equity and filling gaps—can present challenges. A variety of obstacles contribute to the scarcity of financing for low-income solar, including small project sizes, lack of developer balance sheet capacity, both real and perceived issues with credit risk, elevated technical assistance needs, and greater subsidy requirements to pursue goals such as deep energy affordability, climate resilience, or job creation. Still other obstacles are regulatory: for example, not all states allow community solar projects or Power Purchase Agreements, common strategies used for providing low-income solar—and the potential for regulations to shift over time creates risks that mission-driven projects can ill afford. This report synthesizes information garnered from 47 key informant interviews, four focus group discus- sions involving 60 stakeholders, and a review of the substantial existing literature on low-income solar finance to assess the current landscape of mission- driven solar development in the United States, examine the roles that community-based financial institutions could play, and recommend public invest- ments and policy changes that could help to scale the provision of equitable solar finance. Key recommen- dations for policymakers and funders in the renew- able energy and community development fields that emerge from this process include the following: • Help to capitalize and support community-based lenders to provide flexible, low-cost, and long- term financing to mission-driven solar projects— including providing guarantees or other forms of credit enhancement. • Provide federal support for equitable solar, including a grant-in-lieu-of-credits option for the Investment Tax Credit to improve access to this critical government subsidy. • Develop pools of government and philanthropic support that can complement financing from community-based lenders to complete the capi- tal stack for mission-driven projects, as well as to support education and technical assistance to both consumers and potential project sponsors. • Create a national Renewable Energy Credits pro- gram that includes social equity targets to provide a baseline of support for clean energy generation. • Change utility regulations to remove barriers to low-income solar projects; lower permitting costs; provide greater certainty for developers, consumers and owners; and measure progress toward equity in renewable energy policy implementation.

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Case Study: Link Logistics Industrial Solar PV

This case study describes how Link Logistics uses community solar programs and other internal procedures to increase NOI at a warehouse property through leasing roof space for solar installation.

solar, solar PV, photovoltaic, onsite solar, indus↗

Cybersecurity Standards for Photovoltaic Operations

Solar energy plays an important role in securing a more resilient, cyber-secure electrical grid in Pennsylvania. Solar's ability to be widely "distributed" on residential and large roofs, marginal lands, and many other locations across Pennsylvania - as opposed to being centralized - offers a strong option for addressing the myriad of potential disruptions that can occur to the grid's infrastructure. And when combined with energy storage, local energy needs can be met immediately without having to wait on the delivery of an off-site fuel source. As more and more distributed solar electricity generation is brought online, researchers, technology developers, solar developers and grid operators are paying close attention to the potential for solar to enhance grid cybersecurity. Although nobody may know when, where, or how the next cyberattack will take place, there are security measures, technical solutions, and management practices that are being implemented across the industry to protect against network control issues and grid operations. Everyone participating in the solar value chain stands to gain from a coordinated, iterative approach to protect against cyber vulnerabilities and build deeper resilience into the architecture of our grid.

cybersecurity↗

DOE Zero Energy Ready Home Case Study HIA 2020: TC Legend Homes, Everson Net Positive, Everson, WA

Case study of a DOE 2020 Housing Innovation Award winning custom home in a cold climate that got a HERS -19 with PV, with 2,538 square feet and a large south-facing roof, which is designed to hold over 80 solar panels, and the large south-facing windows, bringing in sunlight to warm the concrete floors and provide passive solar heating.

Building America, residential construction, home b↗

DOE Zero Energy Ready Home Case Study HIA 2021: Martha Rose Construction, Abbot’s Alley Net Zero, Sedro Wooley, WA

Case study of a DOE 2021 Housing Innovation Award winning custom home in a marine climate that got a HERS -13 with PV, with 1,804 square feet, highly efficient construction; high-efficiency ductless minisplit heat pumps, appliances, and lighting; triple-pane windows; and 9.9 kW of solar panels on each of the monoplane roofs.

Building America, residential construction, home b↗

Roll-to-roll slot die coating method to create interleaving multi-layered films with chemical slurry coatings

An improved method for manufacturing a continuous self-healing barrier film is provided. The method includes slot-die coating opposing sides of a separator substrate with a curing agent slurry and a curable resin slurry using a single-sided coating line or a tandem coating line. The method also includes sequentially interleaving inner and outer protective layers via a continuous roll-to-roll process to create a multi-layered barrier film. The barrier film can optionally be formed into a barrier envelope, and an insulating core material can be inserted into the barrier envelope to define an enclosure. Evacuating and sealing the enclosure along a perimeter of the barrier envelop forms a self-healing vacuum insulation panel with excellent properties for use as a building material and in refrigeration systems, for example. The barrier film can alternatively be used in the manufacture of tires, roofing, cargo containers, food packaging, and pharmaceutical packaging, for example.

Biswas, Kaushik↗

Decommissioning an Active Historical Reactor Facility at the Savannah River Site - 13453

The Savannah River Site (SRS) is an 802 square-kilometer United States Department of Energy (US DOE) nuclear facility located along the Savannah River near Aiken, South Carolina, where Management and Operations are performed by Savannah River Nuclear Solutions (SRNS). In 2004, DOE recognized SRS as structure within the Cold War Historic District of national, state and local significance composed of the first generation of facilities constructed and operated from 1950 through 1989 to produce plutonium and tritium for our nation's defense. DOE agreed to manage the SRS 105-C Reactor Facility as a potentially historic property due to its significance in supporting the U.S. Cold War Mission and for potential for future interpretation. This reactor has five primary areas within it, including a Disassembly Basin (DB) that received irradiated materials from the reactor, cooled them and prepared the components for loading and transport to a Separation Canyon for processing. The 6,317 square meter area was divided into numerous work/storage areas. The walls between the individual basin compartments have narrow vertical openings called 'slots' that permit the transfer of material from one section to another. Data indicated there was over 830 curies of radioactivity associated with the basin sediments and approximately 9.1 M liters of contaminated water, not including a large quantity of activated reactor equipment, scrap metal, and debris on the basin floor. The need for an action was identified in 2010 to reduce risks to personnel in the facility and to eliminate the possible release of contaminants into the environment. The release of DB water could potentially migrate to the aquifer and contaminate groundwater. DOE, its regulators [U. S. Environmental Protection Agency (USEPA)-Region 4 and the South Carolina Department of Health and Environmental Control (SCDHEC)] and the SC Historical Preservation Office (SHPO) agreed/concurred to perform a non-time critical removal action for the In Situ Decommissioning (ISD) of the 105-C Disassembly Basin. ISD consisted of stabilization/isolation of remaining contaminated water, sediment, activated reactor equipment, and scrap metal by filling the DB with underwater non-structural grout to the appropriate (-4.877 meter) grade-level, thence with dry area non-structural grout to the final -10 centimeter level. The roof over the DB was preserved due to its potential historical significance and to prevent the infiltration of precipitation. Forced evaporation was the form of treatment implemented to remove the approximately 9.1 M liters of contaminated basin water. Using specially formulated grouts, irradiated materials and sediment were treated by solidification/isolation thus reducing their mobility, reducing radiation exposure and creating an engineered barrier thereby preventing access to the contaminants. Grouting provided a low permeability barrier to minimize any potential transport of contaminants to the aquifer. Efforts were made to preserve the historical significance of the Reactor in accordance with the National Historic Preservation Act. ISD provides a cost effective means to isolate and contain residual radioactivity from past nuclear operations allowing natural radioactive decay to reduce hazards to manageable levels. This method limits release of radiological contamination to the environment, minimizes radiation exposure to workers, prevents human/animal access to the hazardous substances, and allows for ongoing monitoring of the decommissioned facility. Field construction was initiated in August 2011; evaporator operations commenced January 2012 and ended July 2012 with over 9 M liters of water treated/removed. Over 8,525 cubic meters of grout were placed, completing in August 2012. The project completed with an excellent safety record, on schedule and under budget. (authors)

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Retrieval System for Calcined Waste for the Idaho Cleanup Project - 12104

This paper describes the conceptual approach to retrieve radioactive calcine waste, hereafter called calcine, from stainless steel storage bins contained within concrete vaults. The retrieval system will allow evacuation of the granular solids (calcine) from the storage bins through the use of stationary vacuum nozzles. The nozzles will use air jets for calcine fluidization and will be able to rotate and direct the fluidization or displacement of the calcine within the bin. Each bin will have a single retrieval system installed prior to operation to prevent worker exposure to the high radiation fields. The addition of an articulated camera arm will allow for operations monitoring and will be equipped with contingency tools to aid in calcine removal. Possible challenges (calcine bridging and rat-holing) associated with calcine retrieval and transport, including potential solutions for bin pressurization, calcine fluidization and waste confinement, are also addressed. The Calcine Disposition Project has the responsibility to retrieve, treat, and package HLW calcine. The calcine retrieval system has been designed to incorporate the functions and technical characteristics as established by the retrieval system functional analysis. By adequately implementing the highest ranking technical characteristics into the design of the retrieval system, the system will be able to satisfy the functional requirements. The retrieval system conceptual design provides the means for removing bulk calcine from the bins of the CSSF vaults. Top-down vacuum retrieval coupled with an articulating camera arm will allow for a robust, contained process capable of evacuating bulk calcine from bins and transporting it to the processing facility. The system is designed to fluidize, vacuum, transport and direct the calcine from its current location to the CSSF roof-top transport lines. An articulating camera arm, deployed through an adjacent access riser, will work in conjunction with the retrieval nozzle to aid in calcine fluidization, remote viewing, clumped calcine breaking and recovery from off-normal conditions. As the design of the retrieval system progresses from conceptual to preliminary, increasing attention will be directed toward detailed design and proof-of- concept testing. (authors)

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The MARSAME Methodology: Fundamentals, Benefits and Applications - 12135

MARSAME is an acronym for the 'Multi-Agency Radiation Survey and Assessment of Materials and Equipment'. Published in January 2009, MARSAME was a joint effort between the U.S. Department of Energy (DOE), the U.S. Department of Defense, the U.S. Department of Energy, and the U.S. Nuclear Regulatory Commission (NRC) to aid sites in the clearance of materials and equipment (M and E). The MARSAME manual supplements the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), published in 1997. As cited in the MARSAME, applicable M and E includes metals, concrete, tools, equipment, piping, conduit, and furniture. Also included are dispersible bulk materials such as trash, rubble, roofing materials, and sludge. Solids stored in containers, as well as liquids and gases, represent additional M and E. The MARSAME methodology covers multiple technical areas, including the initial assessment (IA), Measurement Quality Objectives (MQOs), survey approaches and considerations, survey plans, survey implementation, and Data Quality Assessment (DQA). These topics are generally captured under four phases of the data life cycle, which are Planning, Implementation, Assessment, and Decision-Making. Flexibility and a graded approach are inherent components of the MARSAME methodology pertaining to M and E property clearance programs. Because large quantities of M and E potentially affected by radioactivity are present in the United States, owners of the M and E need to identify acceptable disposition options. Thirteen disposition options, broadly defined under both release and interdiction scenarios, are described in MARSAME. Nine disposition options are listed for release; these options are categorized into two for reuse, two for recycle, four for disposal, and one that is essentially 'status quo' (i.e., maintain current radiological controls). Four interdiction options are also cited. To date, applications of the MARSAME approach for M and E property clearance under reuse scenarios have been limited. However, this should change as familiarity increases. Known examples are provided from DOE-contractor and NRC-licensee facilities. If the methodology is appropriately planned and implemented, the benefits of the MARSAME approach include worker and public protection, reduction in the amount of disposed radioactive waste, reuse of materials (resulting in environmental and material sustainability advantages), and cost savings. (authors)

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