Poster Presentations

Poster Reviews with Authors

This year, Solar Power Northeast created an additional platforms for energy leaders to showcase their expertise in a one-on-one or group setting. Take a break and venture to the Harbor Foyer to hear from the region's leading minds as they share their analysis, ideas, and recommended best practices to help bolster the solar and storage market in the northeastern U.S.

WHEN: Tuesday, February 5
TIME: 3:30 pm - 4:00 pm
WHERE: Westin Boston Waterfront Hotel | Harbor Foyer

Poster Presentation Schedule | Tuesday, February 5


The EnergyScore: An Alternative to Credit Requirements for Low-to-Moderate Income Community Solar
Steph Speirs, Solstice; Sruthi Davuluri, Chikara Onda, Christopher Knittel, Kelly Roache, MIT Educational Institution

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The EnergyScore is an alternative qualifying metric created to approve low-to-moderate income households for community solar energy at scale. Current industry standards - traditional FICO credit score cutoffs ranging between 680 and 750 - are an imperfect predictor of utility payment performance and disproportionately exclude not only lower-credit individuals, but those with insufficient credit history.

The EnergyScore is a machine learning model that uses a “random forest” algorithm to predict the probability of utility account delinquency. It was developed using a sample of nearly 875,000 anonymized account-level records obtained from a major national credit reporting agency. This dataset includes over 5,000 financial and demographic variables, including monthly utility payment performance, tracked over a recent seven-year period. The use of machine learning techniques outperformed earlier probit and linear regression approaches. In the current stage of the analysis, the EnergyScore will be used to qualify low-to-moderate income subscribers for one or more community solar pilot projects, with these data used to iterate and improve the model. Results: The EnergyScore is both a more accurate and inclusive predictor of utility bill payment performance than traditional FICO cutoffs. It consistently displays accuracy rates of 91% in predicting utility bill defaults. When bill delinquency is defined as non-payment for 90+ days, the EnergyScore increases overall accuracy by 38 percentage points compared to an equivalent FICO cutoff of 680. For the low-to-moderate income sample population, the EnergyScore increases approvals by by approximately 11% compared to an equivalent FICO cutoff of 700, while also increasing accuracy by 54 percentage points. Conclusions: This research shows that it is possible to extend solar to a larger number of qualified applicants with lower or no credit scores, while at the same time decreasing default risk - thus opening access to an untapped, low-risk market segment.

Special Design Requirements in the Northeast
Melanie Garza, APA Solar Racking

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As the Northeast is set to explode with solar installations over the next several years, this part of the country has unique and difficult terrain making PV installation more complex than other regions. The Northeast poses a shortened construction season with deep frost lines, high topography and rock. Standard pile foundations prove difficult with deeper embedment depths, high refusals and special engineering. Budgets can be significantly impacted due to installation troubles.

Areas of flat land with good soil are unfortunately not the norm in the northeast. The Appalachian Mountains stretch from Maine down to Alabama encompassing multiple ranges across ME, NH, VT, NY and PA. States along the coast line are known for windswept land and rugged coastal bluffs with extremely rock conditions.
Inaccurate planning and misunderstanding of the difficult environment often leads to excessive cost overruns. A design deficiency in the foundation can cause substantial installation problems and skyrocketing change orders. A variety of foundations and special installation equipment should be considered including ground screws, helicals, piles and ballasts.

It is critically important to work with the customer in the actual design of the project to mitigate any construction related problems before breaking ground. Changes on paper are easier and more cost-effective than after the installation has begun.
Once installation begins, customers often demand a quick installation on a fast track timeline. Given the expected growth and shortage of available installers, schedules will be impacted. Racking manufacturers realize the situation and are quickly trying to reduce installation time through design modifications.

Cost overruns can also be attributed to unpredictable weather conditions, lack of knowledge in local regulations, lack of experience in project location, and equipment shortage.
In this poster presentation, attendees will learn the various foundations available in the solar industry and understand the design requirements best suited for unique soil conditions. Furthermore, construction best practices will be addressed to better control costs and improve installation time.

Although extreme weather or forces beyond human control can impact budgets, in most cases, a project’s overrun is a result of inaccurate analysis or planning before building even starts.

Standard Solar Spearheads the Future of Integrated Roofing Solutions
Daryl Pilon, Standard Solar, Carlisle

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To change the future outcome of solar projects that were previously unfeasible because of the need for roof restoration, providing a synchronized approach solution to that hasn’t been done to date. Develop a true network of solutions providers in both roof and solar in every state, to allow for production of all future solar with avoidance of restrictive costs of roof restoration.

Carlisle uses solar financing to fund roof restoration projects, using Standard Solar’s Power Purchase Agreement (PPA), where SSI provides roof cost avoidance options, and the solar array saves money on electricity costs. In addition, Carlisle provides a specialty combination of spray foam and liquid membranes that ensures roof longevity and is ideal to use with PV roof-mounted systems, complete with a 25-year labor and material warranty. Results: An integrated solar and roof solution, which is packaged in one power purchase agreement, incorporating roof restoration into an energy savings plan. This streamlines the process for the client/building owner, with no money out of their pocket. This collective approach will help companies reach their sustainability goals faster with greater success, receiving a robust solar array resting on a restored roof for years of trouble free savings. Conclusion: Solar opens roofing opportunities, and conversely roofing opens solar opportunities. Aged roofs plus solar awareness plus social and environmental pressures make NOW the time to launch this critical synergy. This collective solution can be scaled around the country with seamless success, allowing projects previously unaffordable to be completed. Combining solar and roof restoration allows for projects to be constructed on roofs that would previously be unsuitable and improves the integrity of solar projects, ensuring long-term benefits

Water-Free Cleaning of PV and CSP Collectors using Electrodynamic Screens for Retrofit and Newly Manufactured Solar Fields
Ryan Eriksen, Malay Mazumder, Mark Horenstein, and Nitin Joglekar, Boston University; Corning Research & Development Corporation; Eastman Kodak

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Natural dust deposition, called soiling, and the loss of output power due to the decrease in collected irradiance, can be a significant challenge for solar power plant operators in arid climates. The current industry standard is deluge or brush washing, which can consume significant volumes of water, usually disrupts plant operation, is labor intensive, and may limit the growth of solar power in arid climates if a water-free method of cleaning cannot be achieved. Other mitigation technologies all have technical challenges limiting their deployment; passive hydrophobic coatings have a limited lifetime and still require water, while robotic cleaning techniques are prone to mechanical failure due to the myriad of moving parts and the dusty environment. The Electrodynamic Screen (EDS) film consists of rows of interdigitated electrodes connected to a power supply. The EDS can be installed on the surface of the solar collector, without significantly affecting light transmission. When the EDS is activated, an electric field charges the dust, and then sweeps the particles from the surface. Cleaning with the EDS system has been shown to restore the output power of a photovoltaic panel to 95% of its original output, and to restore the specular reflectance of a solar mirror to 90% of its original output in laboratory tests. Progress has been made to produce the EDS in a cost effective manner using roll-to-roll production methods on an existing manufacturing line, and in a size that is scalable for large solar fields. Work is now underway to test the EDS in solar fields in the southwestern United States and in international locations. This will be done using an automated testing setup designed to collect the data remotely. The results of these trials will not only allow of a more accurate cost model of the EDS, but will also demonstrate the advantages of the EDS over other conventional cleaning techniques.

Inter-connecting Impaired Properties - The BUILD Act
Juliet Caplinger and Kelley Race, TRC

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In March 2018, Congress passed the Brownfields, Utilization, Investment, and Local Development Act, aka the BUILD Act. The BUILD Act provides $50M+ each year for assessment and cleanup dollars for Brownfields properties which are identified as contaminated or perceived to be contaminated, “impaired” properties. Eligible entities, e.g. municipalities are eligible for grants of $500,000 (with a waiver of up to $650,000) to cleanup up a contaminated property. Of particular interest to solar developers are the incentives in the USEPA Brownfields grant application which allows for new ranking criteria that focuses on renewable energy. As properties are remediated conversations between solar developers and municipalities need to focus on answering the questions needed for interconnecting. Municipalities need to evaluate: is the site cleanup conducive to solar, what type of contamination- soil or groundwater is located on the property, site-specific permitting requirements, zoning, community buy-in, continuing obligations, deed restrictions, and maintenance limitations. While solar developers needs may assess: acreage needed for solar, proximity to interconnect, transmission line substation, 3-phase power availability, interconnect - capacity to carry to power proximity, site layout details - conducive to solar (capping material/grade/slopes/tree line), among others. This poster will utilize the recent Brownfields funding to explore the funding opportunities and the site needs for connecting landowners to developers utilizing USEPA Brownfields funding under the BUILD Act.

Getting a Handle on SMART Program Forecasted Revenue for Early Stage Development Projects
Tom Michelman, Tobin Armstrong, Sustainable Energy Advantage, LLC

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Aim/Objective: The Solar Massachusetts Renewable Target (SMART) program is very appealing as it can provide 20-year fixed revenue streams for projects once they acquire a statement of qualification (SOQ) for which the important prerequisites are a) site control / right to construct, b) all non-ministerial permits, and c) co-signed utility Interconnection Services Agreement (ISA). The problem is how do you know whether to invest in early stage projects if you don’t know what Incentive Block and Adder Tranches those projects will qualify for? The short answer is you will never know with certainty until you acquire a SOQ; nonetheless with the appropriate analysis you can reasonably bound the revenue stream by analyzing the status and trajectory of the SMART program and where you project falls on a relative basis in the interconnection queue project pipeline. Methods: We have constructed and maintain a SMART Program forecasting tool to provide the reasonable and justifiable forecasts of what Incentive Block and Adder Tranche individual projects will qualify for depending upon their development maturity. While information of site control and permitting for projects in the SMART pipeline is opaque, data on the all-important interconnection status are public. Unfortunately, analyzing the available data is not for the faint of heart as it is riddled with idiosyncrasies that will make any analyst scratch their head. Nonetheless, we have conducted wide-ranging analysis of how the SMART program will play out. The SMART Program forecasting tool modeling assumptions are based on extensive SMART market modeling and market research, surveys of the development community, a deep dive into the quality of the data in the interconnection database, and an intimate knowledge of the Massachusetts solar markets. Factors incorporated into the Fortune Teller model include: • SMART program eligibility from the Interconnection Database; • Project milestone reached; • Circuit loading; • Project size (all things being equal, larger projects take longer to acquire an ISA); • Relative position in the Interconnection pipeline; and, • Information gleaned from the SMART Qualification database pipeline. Results: The Poster will provide an overview (e.g., flowchart) of the SMART Program forecasting tool’s approach to SMART Incentive Block and Adder Tranche Forecasting, selected results of the interim analysis that feeds into the model (e.g., historic project success rates and speed to interconnection milestone reached from a cohort analysis taking into account project size, circuit loading), and example forecasts for both projects with and without ISA sent from the electric utility Conclusion: The approach, analysis and results should be of interest to any party with an interest in a project that has yet to attain a SOQ for the SMART Program Incentive Block or relevant Adder Tranche.

Removing Barriers to Interconnection of Distributed Energy Resources (DER)
in Wholesale Markets
Imelda Foley, University of Delaware

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Distributed energy resources (DER) such as solar and storage currently provide value for customers on-site and through utility-level programs such as net metering and demand response. They provide value to ratepayers, as well, by reducing the need for distribution and transmission upgrades. If DER are to provide all the ratepayer and societal value they are capable of, they will need to be allowed to compete alongside utility-scale generation in wholesale markets.

However, various interconnection, operational, and market rules hinder these resources from exporting power to wholesale markets. Within PJM Interconnection (the market operator for 13 states on the East Coast and in the Midwest), DER under state jurisdiction must join a semi-annual interconnection queue with wait times up to 18 months. They are charged deposits for transmission impact studies in the thousands of dollars even for the smallest resources. This is the case even if they have been previously approved for interconnection (e.g., for net metering) by their distribution utility.

I identify current barriers to interconnection, recommend best solutions, and discuss the PJM DER Subcommittee, which is currently considering proposals from stakeholders, including project developers, to modify PJM’s rules regarding DER.

Solar PV and Solar Thermal at Brandeis University
Mary Fischer, Brandeis University

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Since 2010, Brandeis University, in Waltham, MA, has installed over 500 kW of solar PV and solar thermal on campus rooftops. This poster will detail the lessons learned from each PPA, and from the direct ownership of our most recent installation.

How Healthy is Your PV Array?
James Rand, Mason Reed, Core Energy Works

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It can be a very difficult task to understand exactly how your PV array is performing. Monitoring energy output is certainly necessary, but is it sufficient to answer the following: Are all your modules performing above the level guaranteed by the warranty? Are your field wiring and/or field connections limiting your performance? Are there subtle degradation mechanisms operating to lower performance faster than you modeled? Many system owners have used the industry standard 0.5% degradation in their financial modules. Our field experience is that 0.5% is too optimistic in many (perhaps most) cases. Further we have found that energy monitoring alone is not enough to understand the array health. One testing option routinely used is testing modules and strings in the field, which can be inexpensive and relatively easy. Many experts say such measurements are so prone to error as to make the results meaningless. A second option is to dismount modules and ship them for highly controlled laboratory testing, which is expensive and slow. However, to really understand how your modules are performing, a statistically significant sample size is needed. That requirement, along with the excess cost of dismounting modules, makes laboratory testing unrealistic. To fully understand performance, and more importantly, degradation rates over time, Core Energy Works has developed a field-testing protocol that utilizes the following tests: I. Infrared imaging via drone II. Detailed visual inspection III. IV testing of the modules IV. IV testing of the strings V. Measurement of Soiling VI. Electroluminescence test at the module level These methods, taken as a group, can deliver a full report card on the health of a solar array. This testing can be completed in the field in as little as two days with very little disruption of energy generation. No dismounting of modules is required and the accuracy approaches the level of laboratory tests. This poster will explain the motivation for the testing protocol and the benefits it delivers. Examples of issues found impacting performance will be presented, including solar cell degradation, defects in module manufacturing, and wiring failures (both inside the module and with connectors). In addition, Core Energy Works has extensive experience with cracked silicon wafers within modules resulting from both: 1) rough handling during transportation and installation as well as; 2) operation and maintenance activities in the field. Core Energy Works is a small engineering services company. The principal engineers have deep experience in the field performance of silicon-based modules, as well as direct experience with manufacturing, testing, and certifying solar cells and modules. Core Energy Works has visited over 50 commercial and utility scale sites in the past 2 years and fully assessed the performance of over 200 MW of product in the field.