Berkeley Lab Illuminates Price Premiums for U.S. Solar Home Sales

Largest-ever study quantifies the value of rooftop photovoltaics on homes that sold across eight states and 12 years

A multi-institutional research team of scientists led by the U.S. Department of Energy’s Lawrence Berkley Laboratory (Berkeley Lab), in partnership with Sandia National Laboratories, universities, and appraisers found that home buyers consistently have been willing to pay more for homes with host-owned solar photovoltaic (PV) energy systems —averaging about $4 per watt of PV installed—across various states, housing and PV markets, and home types. This equates to a premium of about $15,000 for a typical PV system. The team analyzed almost 22,000 sales of homes, almost 4,000 of which contained PV systems in eight states from 2002 to 2013—producing the most authoritative estimates to date of price premiums for U.S. homes with PV systems.

“Previous studies on PV home premiums have been limited in size and scope,” says Ben Hoen, the lead author of the new report. “We more than doubled the number of PV home sales analyzed, examined a number of states outside of California, and captured the market during the recent housing boom, bust, and recovery.”

More than half a million U.S. homes had PV as of 2014, and the number is growing rapidly. The growth in home PV systems means that the real estate industry will need reliable methods to value these homes appropriately. Further, having greater certainty in those methods will likely facilitate additional growth in the residential PV market.

Hoen is a researcher in the Energy Technologies area of Berkeley Lab, who collaborated with researchers from Adomatis Appraisal Services, Real Property Analytics/Texas A&M University, University of California at San Diego, San Diego State University, and Sandia National Laboratories.

The study also found only a small and non-statistically significant difference between PV premiums for new and existing homes. Additional findings include the existence of a PV “green cachet” (home buyers paying a certain amount for a PV system of any size and incrementally more as system size increases) and an apparent sharp depreciation rate for the PV premium in home sales transactions as those PV systems age. The study also finds that market premiums are statistically similar to those estimated using the income and cost approaches, methods familiar to appraisers. This similarity to standard appraisal practices further bolsters the report’s usefulness to real estate professionals and markets.

“As PV systems become more and more common on U.S. homes, it will be increasingly important to value them accurately, using a variety of methods,” says co-author Sandra Adomatis, an appraiser who helped develop the Appraisal Institute’s Green Addendum and who has written and spoken extensively on valuing green features. She noted, “Our findings should provide greater confidence that PV adds a quantifiable premium to a wide variety of homes in California and beyond.”

The research was supported by funding from the U.S. Department of Energy SunShot Initiative. The SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, DOE supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour. Learn more at

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

Additional Information:

Download the new 2015 report, “Selling into the Sun: Price Premium Analysis of a Multi-State Dataset of Solar Homes”, as well as two fact sheets, and a summary slide deck here.

To register for a related 1-hour webinar at 4 PM Eastern (1 PM Pacific), on January 22nd, 2015 go here: Webinar Registration

Also see earlier LBNL reports on the same subject such as “Exploring California PV Home Premiums” Download the 2013 LBNL Report and “An Analysis of the Effects of Residential Photovoltaic Energy Systems on Home Sales Prices in California” Download the 2011 LBNL Report

For more information on the report, contact Ben Hoen (, 845-758-1896).

Read the release here: 

Tihomir Novakov, 1929-2015

Tihomir (Tica) Novakov, a Serbian-American physicist, passed away as a result of natural causes at the age of 85 in Kensington, California on January 2, 2015. Dr. Novakov was a distinguished member of the Serbian Academy of Sciences and Arts and a Senior Scientist at the Lawrence Berkeley National Laboratory.

Novakov was born in Sombor, Serbia on March 16, 1929. His father was a veterinarian and his mother was a homemaker. While in high school, Novakov began to build x-ray tubes and radios, pursuing scientific knowledge on his own. After graduating from the University of Belgrade with a PhD in Nuclear Physics, he taught at the University of Belgrade and worked at the Vinca Nuclear Institute. Novakov immigrated to the United States in 1963 and worked at Shell Development Company prior to becoming a research scientist at the Lawrence Berkeley National Laboratory (Berkeley Lab) in 1972.

That year, he founded the Atmospheric Aerosol Research Group at Berkeley Lab that spawned the now mainstream field of research on carbonaceous aerosols. The Aerosol Research Group enjoyed an international reputation and conducted groundbreaking research on heterogeneous atmospheric reactions, the importance of carbonaceous aerosols as cloud condensation nuclei, and the optical properties and climate implications of sunlight absorbing black and organic carbon.

In the late 1960s and early 1970s, Novakov’s group was the first to apply X-ray photoelectron and Raman spectroscopy to samples of atmospheric aerosols, which helped to establish the existence of a large elemental or soot fraction and provided definitive identification of physical structures similar to graphite and activated carbon in urban and remote aerosols, including in the Arctic. Following these discoveries, Novakov coined the term “black carbon” to refer to the sunlight absorbing portion of ambient particulate matter. Novakov’s aerosol research group, which included Hal Rosen, Ted Chang, Anthony Hansen, Ray Dod, Henry Benner, and Lara Gundel, developed new analytical techniques for measuring black carbon, the most notable of which is the Aethalometer. The Aethalometer, the name of which is derived from a Greek word that means, “to blacken with soot,” is today the mostly widely used instrument worldwide for measuring atmospheric concentrations of black carbon. Novakov hosted the first International Conference on Carbonaceous Particles in the Atmosphere at Berkeley Lab in 1978 to provide a forum for scientists to discuss this emerging research field. The conference series continues today alternating every few years between Berkeley and Vienna. Novakov retired in 2001 but continued his research as a retiree until 2009, and then as a guest scientist.

Between 1952 and 2013, Novakov authored more than 150 research papers published in peer-reviewed journals that have been cited in more than 6000 articles. Examples (below) of popular titles spanning five decades and his last publication show the breadth and significance of Novakov’s work:

“Sulfates as pollution particulates: catalytic formation on carbon (soot) particles,” Novakov, Chang, and Harker, Science, 1974

“The aethalometer–an instrument for the real-time measurement of optical-absorption by aerosol-particles,” Hansen, Rosen, and Novakov, Science of the Total Environment, 1984

“Large contribution of organic aerosols to cloud-condensation nuclei concentrations,” Novakov and Penner, Nature, 1993

“Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon,” Kirchstetter, Novakov, and Hobbs, Journal of Geophysical Research-Atmospheres, 2004

“The black carbon story: early history and new perspectives,” Novakov and Rosen, AMBIO, 2013.

Much credit can be given to Novakov for establishing black carbon as an important pollutant. A number of recent studies have suggested that black carbon is, next to carbon dioxide, the second strongest contributor to climate change. Novakov’s latest activities focused on historical aspects of anthropogenic aerosols. He continued to conduct research and enjoyed mentoring young scientists until the last month of his life.

Novakov was a polyglot who spoke Serbian, Hungarian, Russian, English and German. A lifelong lover of opera, Novakov was a patron of the San Francisco Opera and the Metropolitan Opera for more than 40 years.

Marica (Mima) Novakov his wife of 60 years passed away in February of 2014. He is survived by the couple’s daughter, Anna Novakov, an Art History professor atSaint Mary’s College of California and granddaughter Christina Novakov-Ritchey, a doctoral student at University of California, Los Angeles.

Thomas Kirchstetter
More about Novakov’s black carbon research.

Local Market Conditions and Policies Strongly Influence Solar PV Pricing

Allan Chen (media contact): (510) 486-4210,

Ryan Wiser (technical contact): (510) 486-5474,

Differences in local market conditions and policies, and other factors, particularly the size of the system, can lead to wide disparities in what consumers across the United States pay to install solar energy systems on their homes or small businesses, according to a recent study published by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). This translates into thousands of dollars difference in the price of comparable solar energy systems around the U.S.

Berkeley Lab’s Ryan Wiser, a co-author of the study, explains its motivation, “Although average prices for solar PV have declined substantially over time, we continue to observe high levels of variability in pricing from one system to another, both within and across regions.” For example, among residential and small commercial systems installed in the United States in 2013, roughly one in five was priced at less than $3.90/ W, while a similar portion was priced above $5.60/W.

Berkeley Lab and researchers at Yale University, the University of Wisconsin-Madison, and the University of Texas-Austin collaborated on the study. The work draws upon Berkeley Lab’s Tracking the Sun annual report series, which monitors trends in the installed price of solar photovoltaic (PV) systems in the United States.

The new study seeks to explain observed differences in pricing, using statistical methods to estimate the effects of a large number of possible influences. These include factors related to system characteristics and household demographics, as well as installer competition, installer experience, demand for PV, and public policy. Understanding these issues can help inform policy and industry efforts aimed at making solar more affordable.

According to Kenneth Gillingham, of Yale University and the lead author of the report, “We found very strong effects associated with the density of installers operating within the local market, leading to differences in PV pricing of more than $0.49/W.” The report suggests that the lower prices in markets with a greater number of active solar installation companies may be due to greater competition and lower information search costs for consumers. The report also found significant price effects associated with installer experience, particularly at the local level.

The overall consumer value of PV – which reflects the size of financial incentives, solar insolation levels, and retail electricity rates – was also found to heavily influence pricing, leading to differences of more than $0.47/W across individual systems. The report offers two possible explanations for this relationship. One is that higher incentives may stimulate demand for PV, naturally leading to higher pricing, as can occur when demand for any good increases. The other is that installers in markets with high incentives and insufficient competition may be able to charge higher mark-ups, though the report does not conclude that this has occurred.

The study focuses on systems ranging in size from 1 to 10 kilowatts (kW). Even within this narrow range, differences in system size were the single largest source of price variability, leading to a $1.50/W price differential between the smallest and largest systems. Other differences in system characteristics, such as tracking equipment or batteries, and installations in residential new construction, also had substantial price impacts.

A wide variety of other explanatory factors for pricing variability were tested and in many cases found to have sizable impacts. The report notes, however, that even after accounting for these many underlying influences, a great deal of pricing variability remained unexplained – suggesting the potential importance of other unobserved contributors and the opportunity for further inquiry.

The report, Deconstructing Solar Photovoltaic Pricing: The Role of Market Structure, Technology, and Policy, by Kenneth Gillingham, Hao Deng, Ryan Wiser, Naim Darghouth, Gregory Nemet, Galen Barbose, Varun Rai, and Changgui Dong, may be downloaded here, along with a factsheet and summary slide deck.

The research was supported by funding from the U.S. Department of Energy SunShot Initiative. The SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, DOE supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour. Learn more at

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

New Research Quantifies Health Benefits of Reducing Greenhouse Gas Emissions

Technical contacts: Jeffery Greenblatt (510) 495-5928,, Dev Millstein (510) 486-4556,

Media contact: Allan Chen, (510) 486-4210,


Reducing greenhouse gas (GHG) emissions, which result from the burning of fossil fuels, also reduces the incidence of health problems from particulate matter (PM) in these emissions.

A team of scientists at the Lawrence Berkeley National Laboratory (Berkeley Lab), the National Institute of Environmental Health Sciences (NIEHS), RAND Corp., and the University of Washington, has calculated that the economic benefit of reduced health impacts from GHG reduction strategies in the U.S. range between $6 and $14 billion annually in 2020, depending on how the reductions are accomplished. This equates to a health benefit of between $40 and $93 per metric ton of carbon dioxide reduction.

“The importance of this result,” says Dev Millstein, Berkeley Lab Project Scientist who participated in the research, “is that avoiding adverse health impacts from particulate matter can help offset the cost of implementing policies that reduce GHG emissions.” Millstein is in the Environmental Energy Technologies Division (EETD) of Berkeley Lab.

The team compared ten different strategies each equal to one “U.S. wedge.” A wedge is a scenario of activities that reduced CO2 emissions by 150 million metric tons per year in 2020, increasing to 750 million metric tons per year in 2060. Increasingly implemented in the marketplace over time, the strategies in each wedge provides greater and greater reductions in carbon emissions compared to what the emissions would have been without the measure (business as usual). The wedge concept was originally devised by Stephen Pacala and Robert Socolow of Princeton University and has become a standard method of analyzing the impact of mitigation measures on greenhouse gas emission. Jeffery Greenblatt, an EETD author of the health benefits study, contributed to writing the original wedge paper and several follow-up papers.

“This paper provides an alternative approach to comparing different ways to reduce greenhouse gases according to how much they improve health,” said John Balbus, M.D., NIEHS Senior Advisory for Public Health. “Decisions about how to address climate change need to be informed by many factors, but we believe this analysis helps advance the thinking on how to bring health considerations into these decisions.”

Strategies considered by the team encompassed efficiency improvements in light- and heavy-duty vehicles, buildings and coal power plants; reducing light-duty vehicle-miles traveled; and substitution of coal electricity with lower-carbon energy sources. Examples of increased building efficiency included adding insulation, sealing and energy-efficient windows; increasing the efficiency of appliances, lighting and miscellaneous plug-load devices such as televisions and computers; and more efficient furnaces and water heaters. Coal power substitution options included natural gas, nuclear, wind and solar photovoltaic power.

In 2020, health savings from one U.S. wedge of GHG reduction could range from $6 billion to $14 billion per year, depending on the strategy, the researchers calculated. If measures were implemented at an accelerated pace, resulting in reductions of 300 million metric tons of CO2 per year by 2020, the savings would range from $10 to $24 billion. The accelerated case represents a situation in which extremely aggressive policies aimed at reducing greenhouse gas emissions were implemented across the U.S.

Health benefits would come primarily from the reduction in particulate matter emissions that would result from movement away from burning of fossil fuels. Particulate matter less than 10 micrometers in size (PM-10) can enter the lungs and bloodstream. PM less than 2.5 micrometers in size (PM-2.5) is considered especially dangerous, and has been linked in numerous studies to increased respiratory symptoms such as coughing and difficulty breathing, decreased lung function, premature death in people with pre-existing conditions, heart attacks, and aggravated asthma.

The researchers estimated by how much each of the ten strategies could decrease GHG emissions, and particulate matter emissions, for each decade through 2060. Well-established health impact functions used in public health studies provided the rate of change between reductions in PM-2.5 and estimates of the number of health outcomes. Their sources included the EPA’s Regulatory Impact Analysis (RIA) for PM2.5 as well as Center for Disease Control and Prevention databases.

“The results of this study provides policymakers with a better understanding of some of the health-related co-benefits of reducing greenhouse gas emissions, an area that is very rarely mentioned when the costs and benefits of reducing climate change impacts are discussed. It provides them with a more complete picture of the true costs and benefits climate change mitigation programs,“ says Greenblatt.

The study “A wedge-based approach to estimating health co-benefits of climate change mitigation activities in the United States” was written by John M. Balbus (NIEH), Jeffery B. Greenblatt (Berkeley Lab), Ramya Chari (RAND Corp.), Dev Millstein (Berkeley Lab), and Kristie L. Ebi (University of Washington, School of Public Health).

Climatic Change, November 2014, Volume 127, Issue 2, pp 199-210

This research was supported in part by Laboratory Directed Research and Development funding at the Lawrence Berkeley National Laboratory.



Los Angeles Air Force Base Demonstrates First Working Vehicle-to-Grid Interconnection in the U.S.

Berkeley Lab team brings together research partners to enable demonstration

Soon, for the first time, a group of researchers will connect a fleet of plug-in electric vehicles (PEVs) to the electricity grid in southern California in a test of the connected fleet’s ability to provide the grid with power and excess storage capacity.

The fleet of 42 PEVs at the Los Angeles Air Force Base (LA AFB) will be controlled by a sophisticated system using technologies developed by Lawrence Berkeley National Laboratory (Berkeley Lab), Akuacom, and Kisensum. The use of vehicle batteries to help buffer the needs of the electricity grid is called Vehicles-to-Grid (V2G), and its use is expected to grow as electric vehicle use expands in California and the rest of the U.S.

A team of scientists at Berkeley Lab’s Environmental Energy Technologies Division (EETD) is leading the work, funding from the Department of Defense’s Environmental Security Technology Certification Program (ESTCP), the California Energy Commission and the U.S. Department of Energy.

“This project is the first time that cars will be used in very fast electric wholesale power markets to address the needs of the electric grid,” says Douglas Black, a mechanical engineer in the Environmental Energy Technologies Division of Berkeley Lab.

Los Angeles Air Force Base is the first federal facility to replace 100 percent of its general-purpose vehicles with plug-in electric vehicles. This fleet is the largest plug-in electric vehicle fleet on a federal facility and the largest V2G demonstration in the world. The fleet can provide more than 700 KW of electric power, enough to run 140 typical American homes on a summer afternoon.

At a recent public roll-out of the fleet, Secretary of the Air Force Deborah Lee James said: “Everything we do to fly, fight and win requires energy, whether it’s aviation fuel for our aircraft or power to run the bases that support them. is vehicle-to-grid pilot is a great example of how Airmen are driving the Air Force forward and finding new and innovative ways to make every dollar count.”

The operators of the electric grid need to bring additional supplies of electricity online, or ramp down power production at any time to match demand, otherwise an unbalanced electric grid will fail, and blackouts will cascade across the system.The grid’s conditions are always changing. On hot summer days, air conditioning causes demand to increase, and it falls as day turns to evening. Electric lights go on at night, toasters and coffeemakers, during breakfast in the morning. Factories may operate at any or all hours of the day and night. Demand fluctuates, often unpredictably, and one of the grid operator’s tasks is to match supply to demand as it changes.

With the addition of more renewable electricity from solar and wind sources, balancing demand will become even more critical. Renewable power sources are intermittent, and their output doesn’t necessarily match demand. The California Independent System Operator (CAISO) expects that by 2015, the growth in power available from renewable sources, especially solar, will require the grid operator to manage a 14,000-megawatt (MW) swing in load during the 5 to 6 pm hour, when the sun sets (reducing power from renewable sources) while lights start to go on in buildings for the evening. That is twice the load swing in 2013. Consequently, CAISO is searching for additional ancillary services—power that it can bring online quickly to help match demand on the grid.

V2G technologies offer one solution to this need, and they also offer a solution to another need in the transportation sector. PEVs (plug-in electric vehicles) are clean vehicles. Their greenhouse gas emissions (from battery charging) and emissions of particulates and nitrogen oxides are much lower than the direct emissions from conventional automotive fleets. California’s 2012 ZEV Action Plangoal is to put 1.5 million zero emission vehicles on the road by 2025. However, plug-in electric vehicles have higher purchase prices and operating costs (because of battery pack replacement) than conventional cars.

The higher cost to buy and operate PEVs has slowed their adoption in the marketplace. Using the electricity storage capacity of PEV fleet batteries can help make their economics more favorable. Bidding power from PEV fleets’ batteries into the CAISO power markets could help meet rapid swings in load on the grid, and provide a revenue stream to fleet owners that offsets their high costs.

Enter the Department of Defense. An Executive Order requires federal agencies including DoD to reduce their fleet’s total consumption of petroleum products by two percent annually, and to use plug-in hybrid vehicles when available at a reasonably comparable cost. Another federal mandate requires DoD to prefer the lease or procurement of motor vehicles using electric or hybrid propulsion systems, if comparable in cost. DoD has identified V2G as a key technology for development in its efforts to meet these requirements. DoD’s current non-tactical fleet totals 200,000 vehicles.

Los AngelesAFB as test case

Setting up this research project has required a significant effort to bring together many players—the Los Angeles Air Force Base is located in Southern California Edison service territory. Although designated an air force base, it consists primarily ofbuildings. The mission of LA AFB’s staff is managing defense contracts with the nearby aerospace industry—there are no runways or aircraft at the base, but there is about 90,000 square meters of office space.


The project has other participants, all of whom are working together to pioneer the V2G solution. Selling ancillary services into the California electric grid requires the oversight of the California Independent System Operator. The hardware to manage the scheduling of the fleet’s power sales into the CAISO power market is provided by Akuacom’s DRAS server, using software that follows the OpenADR protocol developed by Berkeley Lab’s Demand Response Research Center allows grid operators, utilities and customer sites to communicate in a common language.

Kisensum’s software will manage fleet and charging services. The software schedules services requested of the fleet, and collects data about fleet status, including the charge state of each vehicle. The software also manages the charge stations, and charging and discharge of vehicles. When the CAISO requests that power from the fleet be discharged into the electric grid, this software manages that process.

Finally, Berkeley Lab’s DER-CAM software (Distributed Energy Resources Customer Adoption Model) uses data about the state of the fleet and the opportunities in the ancillary services market to forecast the market’s prices and grid energy requirements, weather, and other factors, and generate optimal scheduling for the fleet. Collectively these technologies are called the PEV Fleet Optimization Model (PEV2GOpt).

There are both technological challenges to making this system work together, and policy and regulatory challenges that must be overcome. Southern California Edison has worked to address the regulatory barriers and establish the V2G interconnection.

“This is pioneering research,” says Black, “we are paving the way for a diverse set of stakeholders to work together. What we’re doing will provide a model for expanding V2G throughout the U.S.”

A portion of the PEV fleet of 42 cars has been delivered to LA AFB. The research team is installing equipment for test throughout the month. The Air Force’s PEV fleet at Los Angeles AFB will include both electric and hybrid vehicles, and will consist of 19 sedans, five pick-up trucks, 13 vans, four medium-duty trucks and one 12-passenger bus.

The goal of this research is assess how much the revenue from providing electricity services to the grid can offset the cost of buying and managing a PEV fleet, as well as the potential benefits to the grid of V2G services. The researchers also hope to assess the economic viability of converting more of DoD’s non-tactical fleet to PEVs.V2G installations are best suited to smoothing out small discrepancies between electric demand and supply that require extremely quick responses—within seconds of being called up, what the CAISO terms “regulation.” They are not currently considered as operating reserves, which provide sustained back-up power in the event of, for example, apower plant failing—PEV fleets currently cannot discharge enough power for several hours to make up for a large shortfall of that sort.

“If we are successful, we will show that the increased cost of electric vehicles can be offset with the value they can extract from the marketplace, which will increase their adoption and accelerate the reduction of greenhouse gases from transportation,” says Black.

—Allan Chen

U.S. Air Force press release

New website focuses on applying lessons of Berkeley Lab’s energy-efficient glazing and facades research

A new website intended to help architects, building engineers, and manufacturers develop and make better use of energy-efficient glazing and façade systems in commercial buildings is now available. Developed by the Windows and Envelope Materials Group of the Environmental Energy Technologies Division (EETD), at Lawrence Berkeley National Laboratory (Berkeley Lab), “Low Energy, High Performance Building Façade Solutions” is designed to help the building industry apply lessons learned from EETD’s advanced research to façade design best practices. It is the result of a collaborative multi-year program funded by the Department of Energy and the California Energy Commission’s Public Interest Energy Research Program.

“New fenestration technologies and systems that optimize the synergies between the façade, lighting, and mechanical systems can deliver high performance throughout a building’s lifespan,” says Eleanor Lee, Staff Scientist and Deputy Group Leader in the Building Technology and Urban Systems Department. “These ‘integrated’ solutions represent a key opportunity to significantly reduce energy and demand, helping to move us toward our goal of zero net energy buildings by 2030.”

Glazing and façade systems have very large impacts on all aspects of commercial building performance. They directly influence peak heating and cooling loads, and indirectly influence lighting loads when daylighting is considered. In addition to being a major determinant of annual energy use, they can have significant impacts on peak cooling system sizing, electric load shape, and peak electric demand. Because façades are prominent architectural and design elements, and because they influence occupant preference, satisfaction, comfort, and health, the design optimization challenge is more complex than with many other building systems.

Learn more about EETD’s research on low-energy, high-performance building façade solutions at The site includes downloadable guidebooks, research reports, and windows- and facades-related design software.


Microgrid Version of Distributed Energy Resource Software Is Now Available

DER-CAM Version 4.1.3

Lawrence Berkeley National Laboratory (Berkeley Lab) has released DER-CAM 4.1.3, the latest version of the Distributed Energy Resources – Customer Adoption Model (DER-CAM). This new version, released on October 1, 2014, improves on previous DER-CAM versions by bringing new capabilities focused on some of the key issues pertaining to microgrids and to their planning process.

DER-CAM 4.1.3 optimizes generation resources and loads within the boundaries of the microgrid in both grid-connected and islanded operational modes and establishes a useful microgrid design tool. DER-CAM now takes into account the synergies between grid-connected and islanded conditions, showing maximized benefits between the wide varieties of technologies possible in a microgrid: internal combustion engines, fuel cells, gas turbines, wind, solar, PV, heat pumps, electric and heat storage, combined heat and power (CHP), bio-fuel, natural gas, diesel, electric vehicles (EVs), demand response, and storage. DER-CAM also considers energy efficiency improvements at facilities, such as windows and walls that directly relate to changes in electric and heating loads and impact the generation technologies within the microgrid. ZNEB conditions can be considered as well. Further, DER-CAM considers policy measures and incentives that impact microgrid development and design, thus supporting high penetrations of generation from renewable energy resources, while maintaining reliability, offering resiliency, and achieving economic and environmental objectives.

DER-CAM 4.1.3 introduces a value-added feature for resiliency: the possibility of defining utility outage events of varying durations, from a few minutes to several days or weeks. During these events, when the microgrid is forced into islanding, DER-CAM now provides a way to determine the size of the equipment required to withstand the period of disconnection, whether hours, days or weeks.

Another valuable feature is the ability to model different load priorities, enabling the user to define critical loads. The management of priority loads is particularly important when managing limited generation resources (including storage) during periods of extended outages. As load priorities are linked to outage valuation, DER-CAM can be used to quickly assess the site costs in the event of an outage. By introducing back-up specific technologies it can be used to analyze the trade-off between adding additional reserve capacity of standard generation and storage equipment, or adding equipment solely for the purpose of backup during outage events.

A new web-based graphical user interface, specifically for version 4.1.3, is under development and will be available on-line starting November 1, 2014. Companies will be offered an opportunity to use it and test its usability. With this web interface users will be able to run the model and interpret its results without installing DER-CAM locally. For more information please refer to

Different versions of DER-CAM have been used for academic and commercial studies on distributed energy resources by universities, research institutions, utilities, and commercial companies for over ten years, as noted in more than 150 public reports, journal papers, and project reports. Now this same proven model can be used for microgrids.

Please see a recent article on the latest DER-CAM version in the IEEE Smart Grid Newsletter


Michael Stadler, (510) 486-4929

Searching for Real-Time Measurements of Electric Grid Health

Today’s electric grid faces an array of threats and opportunities—threats from aging equipment, catastrophic weather and other factors, and opportunities from clean, customer-sourced of power such as solar and wind generation, and demand response (DR). A key to managing the new grid is to be able to measure its health in real-time—faster than second to second. Measuring a key grid parameter, “synchrophasors,” offers a solution to the real-time measurement problem.

A new project, funded by the Advanced Research Projects Agency-Energy (ARPA-E), aims to give electricity grid operators a futuristic, microsecond-to-microsecond measurement of the state of electric distribution lines using “microsynchrophasors.” Scientists at the University of California, Lawrence Berkeley National Laboratory (Berkeley Lab), the California Institute for Energy and Environment (CIEE), and Power Standards Lab of Alameda, California, are performing the research.

The project’s goal,” says Emma Steward, an engineer in the Environmental Energy Technologies Division (EETD) of Berkeley Lab, “is to learn how to use phase angles [phasors] on distribution systems to better understand what’s happening on these systems.”

Transmission and distribution lines carry our power from sources to consumers. Transmission lines carry power over long distances at high voltages. The distribution transformers and lines step down this power, sending it to homes, businesses and industrial facilities. Synchrophasors are already beginning to be deployed on transmission lines. The groundbreaking ARPA-E research seeks to bring this real-time measurement capability to the electrical distribution system.


From one-way to multi-directional power flow

Just 20 years ago, most of the power flowing through the electricity grid was traveling from mainly utility-owned power plants to customers. Those plants were usually coal- or natural gas-fired, or nuclear. Almost all of the customers, except some large industrial facilities with onsite power generation, were consumers, not producers of power.

Things changed in one generation. Today, renewable power sources provide a growing percentage of power on the grid, helping reduce climate by lowering greenhouse gas emissions. These sources are intermittent—the power flows when the sun shines or the wind blows.

Another change from the past is that customers have options to interact with the grid. They can reduce their power consumption during periods of high power prices through demand response (DR) programs. DR is becoming automated (AutoDR) and widely adopted thanks to R&D at Berkeley Lab’s Demand Response Research Center (DRRC).

Industrial and commercial power consumers are creating microgrids—producing power for their own facilities distributed through small grids that can be disconnected from the larger electric grid, and reconnected to the grid when the consumer needs additional power, or has an excess to sell.

The electric power industry is more complicated today, but it offers more opportunities for clean energy and customer engagement.

These changes require electric system operators (known as independent system operators, ISOs) to have a more accurate read of the state and the health of the power grid in real-time. Instabilities in power, caused by fluctuations in supply and demand from the intermittency of renewables, sudden changes in demand response availability, demand changes caused by weather, catastrophe, or equipment failure, and the general aging of the grid infrastructure mean that there are more threats to delivering power reliably and continuously. The electric power industry needed a better way to know what’s happening on the grid in real time, to respond more quickly to these threats.


Synchrophasors: A revolution in grid measurement

The electric power industry found a solution in the form of synchrophasors.

Power is traditionally transmitted in the form of an alternating current. The current looks like a sinusoidal wave, with peaks and troughs. However, the waveform produced by each plant will not peak and bottom out at the same time as any other plant—the power that plants produce is not perfectly synchronized. Phase angle is a measure of the difference between two sinusoidal waves—it measures how far the peaks and troughs are from one another.

Power engineers know how to measure a quantity called a phasor at any point on an electrical grid with an instrument called a phasor measurement unit (PMU). Phasors are a measure of the phase angle, and the magnitude of voltage at a certain point on the grid. Measuring a large number of phasors at exactly the same time, a measurement known as a synchrophasor, tells grid managers something about the health of the grid.

Synchrophasors can tell them, for example, whether the demand for power matches supply, whether the power is flowing in the correct directions from supply to demand, and if there are any fluctuations in power that might cause grid instability. The precise, nearly simultaneous measurements are made possible by GPS systems, which can provide timing down to the microsecond time scale (one-one millionth of a second).

Today, synchrophasor measurements on the transmission lines of the electric power grid are becoming more common. Thanks in part to research and demonstration projects managed by the Consortium for Electricity Reliability Solutions (CERTS), based at Berkeley Lab, ISOs throughout the U.S. are expanding their use of synchrophasors.

Measuring conditions on distribution lines, however, provides a distinct challenge, one that the ARPA-E project is addressing.


Distribution Systems Need More Accurate Measurements

Distribution systems are the portions of the grid where electric power is stepped down from a transmission line’s high voltages to voltages appropriate to household, commercial and industrial customers by transformers at substations, and transmitted to homes, businesses and industrial facilities.

“We think that measurements of ‘microsynchrophasors’ will provide a better visualization of what’s going on, and it will allow ISOs to detect problems on the distribution system and plan their responses before problems run out of control,” says Stewart.”

Because the power flow through transmission lines is smaller, the equipment must be able to measure phase angles that are at least an order of magnitude smaller than on transmission lines. The signal will also be noisier because of interference from the devices connected to the grid by consumers and from utility equipment at transformer stations. One of the research partners, Power Standards Lab, has developed a microsynchrophasor measurement unit (µPMU) capable of making the accurate measurements required on the distribution grid. Synchrophasors are typically measured 24 times per cycle. The prototype µPMU can take 512 measurements per cycle.


Figure 1: Time Scale for µPMU Performance (Source: Alexandra Von Meier, CIEE)


Multiple Program Elements

The research partners are each leading a different research activity. UC Berkeley team members are developing a network capable of recording and processing data and communicating with µPMUs installed in the field. They are also studying how the data can support diagnostic of problems on distribution systems. PSL developed the µPMU device and is evaluating its performance. The California Institute for Energy and the Environment is studying how µPMU can be used in controlling applications on the grid such as managing microgrid connection to the larger grid. Berkeley Lab leads field-testing of µPMUs on several utility grids.

With ARPA-E’s funding, Berkeley Lab is testing µPMUs in four electric utilities’ service territories. When the pilot installations are complete, there will be one at each partner utility. About 10 µPMUs will be split over one or two distribution feeders at each site. In addition, seven µPMUs have been or will be installed on one of Berkeley Lab’s distribution feeders (Figure 2). Data from the devices are collected wirelessly and sent via a 4G network to a database on the UC Berkeley campus. The testing will last two years. Stewart and her colleagues are also modeling distribution circuits, and will use data from the field tests to validate their model.

PE 1 PSL - Quarter 3 Oct 2013-Jan 2014 Progress Report_2

Figure 2. Microsynchrophasor test unit installed at a Berkeley Lab transformer station.

“One application of this research will be to understand what happens when a microgrid synchronizes and desynchronizes from the electric grid,” says Stewart. The measurements can help coordinate resources between microgrids and the electric grid.

The research will also evaluate whether the systems could improve the management of demand response. “A goal of the study is characterizing the loads during demand resources,” Stewart notes. “When customers turn loads on and off at the same time, it could affect the state of the grid.

Microsynchrophasor measurements are ideal for detecting and locating faults that might lead to instabilities on the grid resulting from sudden imbalances in supply and demand.” They also have the potential to help system operators better manage the use of intermittent renewable sources of power, and to help match supply to demand through demand response programs and grid storage.

“Utilities are excited about this research,” says Stewart. “They are always looking for more information about the state of the grid.”

—Allan Chen

More information:

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Berkeley Lab Report Quantifies the Financial Impacts of Customer-Sited Photovoltaics on Electric Utilities

Impacts to Utility Shareholder Earnings and Return on Equity Can Vary Greatly, and Can Be Mitigated through a Range of Measures

Allan Chen (media contact): (510) 486-4210,

Galen Barbose (technical contact): (510) 495-2593,

Berkeley, CA — A new report prepared by analysts from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) examines the potential impacts of customer-sited solar photovoltaics (PV) on electric utility profitability and rates.  The report, entitled Financial Impacts of Net-Metered PV on Utilities and Ratepayers: A Scoping Study of Two Prototypical U.S. Utilities, shows that these impacts can vary greatly depending upon the specific circumstances of the utility and may be reduced through a variety of regulatory and ratemaking measures.

Adoption of distributed PV by residential and commercial customers has expanded rapidly in recent years, driven in part by the prevalence of net metering, a billing arrangement that allows customers to offset their usage with PV generation and receive credits against future usage for excess generation.  Although distributed PV generation currently represents roughly 0.2 percent of the nation’s electricity supply, and no more than 1 to 2 percent in most states, widespread debates have surfaced about the financial impacts of distributed PV on utilities and their customers.

According to Berkeley Lab’s Galen Barbose, one of the report’s authors, “This work is intended to fill a gap in those debates by providing some concrete information about the potential magnitude of the financial impacts, by identifying the key conditions under which they may become more or less severe, and by evaluating possible strategies for reducing their severity.”

The analysis, using a financial model developed by Berkeley Lab, is based on two prototypical utilities – a vertically integrated utility in the southwest and a wires-only utility in the northeast – and estimates the possible financial impacts of distributed PV on both utility shareholders and ratepayers.

At PV adoption levels equal to 2.5 percent of total utility retail sales, which is greater than levels that currently exist in all but one state, Berkeley Lab found that distributed PV resulted in about a 4 percent reduction in shareholder earnings for each of the two utilities.  The impacts on average retail electricity rates, however, were considerably smaller, with increases of 0.1 and 0.2 percent, respectively.

The study also includes a large number of sensitivity cases with alternate assumptions about the two utilities.  As Andrew Satchwell, a co-author of the report, adds, “One important contribution of this work is to highlight the degree to which the impacts of distributed PV on utility shareholders and ratepayers can depend on particular details of the utility’s operating and regulatory environment.”

In considering a future in which distributed PV increases to reach 10 percent of total utility electricity sales – which is much greater than current adoption rates – the report estimates that shareholder earnings might be reduced by anywhere from 5 to 13 percent for the southwestern utility and by 6 to 41 percent for the northeastern utility.  Those ranges reflect alternate assumptions about the utilities’ underlying load growth, rate structure, and other factors, as well as uncertainty about the degree to which distributed PV defers the need for utility capital investments in new generation, transmission, and distribution infrastructure.

A core purpose of the study was to evaluate measures that could be pursued by utilities and regulators to reduce the financial impacts of distributed PV.  The report considered a large number of such measures, including changes to utility rate design and ratemaking processes, mechanisms that allow utilities to recoup revenues lost due to distributed PV or to earn profits on distributed PV, and a variety of other strategies.

As the report shows, a number of these measures could restore utility profitability to levels similar to what would occur in the absence of distributed PV, or could offset rate increases associated with distributed PV, or both.  However, as Andrew Mills, another co-author of the report, explains, “The effectiveness of these measures often depends critically on how they’re designed, and in many cases, they involve important tradeoffs – either between utility ratepayers and shareholders or among competing policy objectives.”

As such, the report does not offer specific recommendations, but rather seeks to highlight important issues for utilities and regulators to consider as they weigh issues surrounding distributed PV and net metering.

The report as well as a summary briefing may be downloaded here or from

A webinar presentation of key findings from the report will be conducted on Thursday, October 9th at 10:00 am Pacific Time.  Register for the webinar here.

The research was supported by funding from the U.S. Department of Energy SunShot Initiative. The SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, DOE supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour. Learn more at

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit

New Studies Find Significant Declines in Price of Rooftop and Utility-Scale Solar; Onerous Local Regulatory Processes Can Impact System Prices

Allan Chen (media contact): (510) 486-4210,

Mark Bolinger (technical contact): (603) 795-4937,

Galen Barbose (technical contact): (510) 495-2593,

Ryan Wiser (technical contact): (510) 486-5474,

Berkeley, CA — The price of solar energy in the United States continues to fall substantially, according to the latest editions of two annual reports produced by the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab)

A third Berkeley Lab report, written in collaboration with researchers at Yale University, the University of Texas at Austin and the U.S. Department of Energy (DOE), shows that local permitting and other regulatory procedures can significantly impact residential photovoltaic (PV) prices.

According to the second edition of the Utility-Scale Solar report, larger utility-scale solar projects in the United States have made great strides in delivering competitively priced renewable electricity in recent years.

“The price of electricity sold to utilities under long term contracts from large-scale solar power projects has fallen by more than 70% since 2008, to just $50/MWh on average within a sample of contracts signed in 2013 or 2014 and concentrated among projects located in the southwestern United States,” explains Mark Bolinger of Berkeley Lab, one of the report’s authors.

Meanwhile, the average, up-front installed price of utility-scale PV projects dropped by more than one-third since the 2007-2009 period, and average project-level performance has also increased recently.

The report tracks data on installed project costs or prices, operating costs, capacity factors, and power purchase agreement prices. It focuses on ground-mounted solar projects larger than 5 MW in size, and covers both PV and concentrating solar power.

“With the growth in this segment of the solar market in recent years, we are now able to systematically review actual market data to directly observe what large-scale solar projects cost to build, how they are performing, and at what price they are selling electricity,” notes report co-author Samantha Weaver.

According to the latest edition of Tracking the Sun, an annual PV cost tracking report produced by Berkeley Lab, installed prices for residential and commercial PV systems completed in 2013 fell by roughly $0.70 per watt (W) or 12 to 15 percent from the prior year.

“This marked the fourth consecutive year of significant price reductions for residential and commercial systems in the U.S.,” explains Galen Barbose, one of the report’s authors. Within the first six months of 2014, prices for such PV systems in many of the largest state markets have continued on their downward trajectory.

The continued decline in PV system pricing is especially noteworthy given the relatively steady price of PV modules since 2012. In recent years, reductions in the installed price of PV systems have been driven largely by the falling price of PV modules, but that dynamic appears to be shifting.  In particular, the report points to the increasing importance of reductions in soft costs – which include such things as marketing and customer acquisition, system design, installation labor, and the various costs associated with permitting and inspections.

As module prices have fallen, industry and policymakers have increasingly targeted soft costs for further reductions. As Berkeley Lab’s Naïm Darghouth, another of the report’s authors, notes, “The fact that system prices have continued to fall, despite the flattening of module prices, suggests that the various initiatives targeting soft costs are beginning to bear fruit.”

The two Berkeley Lab cost-tracking reports released today also highlight the wide variability in PV system pricing, detailing the installed price differences that exist across states and across various types of PV applications and system configurations.  For example, roughly 20 percent of all residential systems installed in 2013 were priced at or below $3.90/W, while an equal proportion was above $5.60/W.

Based on a third Berkeley Lab report released today, How Much Do Local Regulations Matter?, some of this variation in residential PV pricing is driven by differences in local permitting and other regulatory procedures.

In particular, based on data from Vote Solar and Berkeley Lab, variations in permitting among cities can drive differences in average residential PV prices of as much as $0.18/W, or $900 for a typical residential PV installation. Based on data from DOE, meanwhile, variations in not only permitting but also a wide range of other local procedures (interconnection, planning and zoning, net metering and financing) can drive even-larger PV price differences among cities: two different statistical models estimate maximum city-level average price differences of $0.64/W and $0.93/W, or approximately $3,000 for a typical PV system.

“A variety of efforts are underway to make local procedures less onerous, and more conducive to solar market growth,” explains Ryan Wiser of Berkeley Lab. “These results highlight the magnitude of PV price reductions that might be possible through streamlining burdensome local regulatory procedures.

The three reports, along with related summary slide decks, two-page fact sheets and data files (as applicable), are available for download at: Upcoming webinars on these reports will be announced in the near future.

This research was supported by funding from the U.S. Department of Energy SunShot Initiative. The SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, DOE supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour. Learn more at

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit  DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.  For more information, please visit