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Glare Study Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 1 Executive Summary Nexamp has been selected by Warren County to develop a solar photovoltaic (PV) project at Floyd Bennett Memorial Airport (GFL) in Queensbury, New York. The project includes two arrays: a north array near runway end 19 and a south array near runway end 1. As the projects are proposed on airport property, glare is assessed relative to the Federal Aviation Administration’s (FAA) “Policy, Solar Energy System Projects on Federally-Obligated Airports.” Nexamp has engaged Barrett Energy Resources Group (BERG) to evaluate potential glare impacts of the proposed solar PV project on airport sensitive receptors at GFL. To complete this task, BERG has utilized the Solar Glare Hazard Analysis Tool (SGHAT) to predict potential glare and has assessed the results relative to the FAA’s Solar Policy and ocular hazard standard. While the Final Policy issued in May 2021 does not require an analysis for airports without an air traffic control tower, for planning purposes, glare on pilots relative to the FAA’s Interim Policy (2013) has been considered. The findings show that as designed the project results in no glare on aviation receptors, which is compatible with the ocular hazard standard contained in the FAA’s 2013 Policy. This memorandum describes the methodology and results of the glare study. Project Description Nexamp is proposing two solar PV arrays with a combined capacity of 13.5 MWdc as shown on Figure 1. The north array is located west of the end of runway 19. The south array is located off the end of runway 1 and is designed with a clear pathway through the array for safe emergency landing. The systems are designed with single axis tracking whereby the panels follow the path of the sun each day. Floyd Bennett Memorial Airport (GFL) is a general aviation airport owned and operated by Warren County. It has two asphalt cross runways, 1/19 and 12/30. It does not have an air traffic control tower. Technical Memorandum To: Dallas Manson, Nexamp Inc. From: Stephen Barrett Date: April 29, 2022 RE: Glare Study, Solar PV Projects at Floyd Bennett Memorial Airport, Queensbury, New York Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 2 Figure 1. Solar Projects Proposed at GFL FAA Solar Policy In response to the growing solar electricity market and the specific interests of airports and their tenants to develop solar projects on airport property, the FAA published “Interim Policy, FAA Review of Solar Energy System Projects on Federally-Obligated Airport” in October 2013. The Policy is intended to communicate to airports and FAA technical reviewers the methods for assessing glare from solar PV projects proposed on airport property and the standards for determining impact. It also specifies the use of modeling to assess glare and directs project proposers to the Solar Glare Hazard Analysis Tool (SGHAT) which was developed by the US Department of Energy at the request of the FAA. The FAA Solar Policy was issued as Final in May 2021. However, the Interim Policy is still referred to as guidance for planning projects. Glare Methodology and Standard of Impact Prediction of potential glare occurrence from a solar PV project requires knowledge of the sun position, observer location, and the solar module/array characteristics (e.g., location, extent, tilt, azimuth or orientation, etc.). The path of glare is governed by the law of reflection which states that the angle of incidence equals the angle of reflection as shown in Figure 2. Vector algebra is then used to determine if glare would be visible from the prescribed observation points. Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 3 Figure 2. Law of Reflection Figure 3 provides a simple representation of how the sun can produce glare on an air traffic control tower for a specific time and location. For glare from the sun to reflect off a solar array and impact receptors on the ground, the sun’s position must be low on the horizon (e.g., shortly after sunrise and before sunset). As the sun moves, the incidence of glare subsides. Figure 3. Geometric Representation of Potential Glare Impacts from the Sun Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 4 The FAA’s Solar Policy specifies the glare methodology and ocular hazard standard required for solar PV projects located at airports. The Policy directs proponents to model glare using SGHAT or an acceptable alternative. For this analysis, BERG used SGHAT version 3 released in the spring of 2016 under the brand “GlareGauge.” For consistency with the FAA Policy, the model is referred to as SGHAT. With regards to the ocular hazard standard, the SGHAT model reports predicted glare intensity in a color-coded system at three levels: • green, a low potential for an after-image1; • yellow, a potential for an after-image; and • red, a potential for retinal burn. The Policy includes an ocular hazard standard which establishes the glare intensity depicted by the color-coded system that is deemed significant and thereby determined to produce a potential hazard to air navigation. The standard in the Interim Policy (2013) prohibits any glare from impacting the air traffic control tower (ATCT) (i.e. results with green, yellow or red represent a significant impact), but allows for a low potential for an after image (green) for pilots on approach to the airport with yellow and red results representing a significant impact. In the Final Policy (2021), the FAA determined that glare from solar panels on pilots is not novel, and therefore any glare is insignificant. While the FAA now only requires a glare analysis for the ATCT, the model will produce results for aircraft which can be considered relative to the Interim Policy as guidance. SGHAT Model Setup for the Proposed Project For the GFL Solar Project, BERG used the PV project polygon tool to draw the footprint of each solar array on SGHAT’s interactive Google map, and then input the fundamental solar PV design elements. As the project proposes a single axis tracking system, SGHAT includes relevant fields for those elements including for this project design: • a maximum angle of 60°; • a resting angle of 60°; • backtracking method of shade-slope which minimizes shading; • panel height of 20 feet above ground level (agl); and • panel surface including anti-reflective coating. 1 An after-image occurs when you look directly into a bright light, then look away. It typically takes several seconds for your vision to readjust and return to normal. It is also referred to as a temporary visual disability or flash blindness. Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 5 Figure 4 is a simple schematic showing how the solar panels track the sun’s position throughout the day. Figure 4. Schematic of Solar Tracking System Through a One-Day Cycle The next step is to input information on the airport sensitive receptors to be analyzed in the model. Floyd Bennet Memorial Airport does not have an air traffic control tower (ATCT) and therefore this analysis is not required. It does have two runways with four runway ends that were analyzed. To assess glare on pilots, BERG activated the flight path tool and selected the threshold (or end) of the first runway and selected a second point away from the threshold to represent a straight-on approach pathway. The model automatically draws the flightpath from the threshold out to two miles for analysis. This step was repeated for the other three approach pathways. Figure 5 shows the location of the solar array and the two-mile flight paths (in light purple) analyzed in accordance with FAA methodology. Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 6 Figure 5. Airport Sensitive Receptors at Floyd Bennett Memorial Airport The glare analysis button was activated and the model calculated glare from various sun angles at 1-minute intervals throughout the year to predict if glare could be observed by the specified sensitive receptors. Glare Model Results and Analysis The SGHAT model output for the analysis of aviation receptors at GFL is included as Attachment A. The report shows that no glare is predicted to impact pilots on final approach to each of the four runway ends. Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 7 The single axis tracking system is effective in eliminating potential glare from receptors close to the ground. This is due first to the design and operational elements where the face of the panel is always perpendicular to the sun as the sun moves across the sky during the day. The effect is that the sun’s rays contact the panel and the portion that is reflected returns back toward the sun and not toward any receptor on the ground. This concept is illustrated in Figure 6. Figure 6. Tracking System Mitigates Glare for Low-to-Ground Receptors The second project element of the tracking system that mitigates glare is the starting and stopping angle of the panels. Because the panels do not extract much energy from the sun when it is low on the horizon, the tracking system does not remain perpendicular to the sun at the beginning and end of each day. If it did, the sun may contact the panel surface and reflect back toward the sun at a low angle and close to the ground. Instead, the panel is already angled such that any reflection from the rising or setting sun is cast upward and away from the ground. Once the sun rises to a position in the sky where it is perpendicular to the panel “resting” angle, the tracking commences. At the end of the day, the panel reaches the same angle where it started the day, stops tracking, and, as the sun continues to set, any reflection off the panel is cast upward. This concept is also shown in Figure 6. Conclusions Barrett Energy Resources Group (BERG) has evaluated potential glare impacts for two solar arrays being developed by Nexamp on airport property at Floyd Bennett Memorial Airport (GFL). The North and South Arrays are both ground-mounted, single axis tracking systems with a combined capacity of 13.5 MWdc. While the airport does not have an air traffic control tower, the Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 8 analysis seeks to evaluate compliance with the FAA’s Interim Policy of 2013 and potential effects on pilots. The SGHAT model registered no glare for all of the receptors analyzed. This result is consistent with the operation of the single axis tracking design which is effective at mitigating glare on sensitive receptors close to the ground. Barrett Energy Resources Group PO Box 1004 | Concord, MA 01742 | 339-234-2696 www.barrettenergygroup.com 4/29/2022 9 Attachment A Glare Modeling Results FORGESOLAR GLARE ANALYSIS Project: Floyd Bennett Airport Solar A 13.1 MWdc ground-mounted single axis tracking solar facility in two locations. Site configuration: Preferred Analysis conducted by Stephen Barrett (steve@barrettenergygroup.com) at 15:38 on 28 Apr, 2022. U.S. FAA 2013 Policy Adherence The following table summarizes the policy adherence of the glare analysis based on the 2013 U.S. Federal Aviation Administration Interim Policy 78 FR 63276. This policy requires the following criteria be met for solar energy systems on airport property: • No "yellow" glare (potential for after-image) for any flight path from threshold to 2 miles • No glare of any kind for Air Traffic Control Tower(s) ("ATCT") at cab height. • Default analysis and observer characteristics (see list below) ForgeSolar does not represent or speak officially for the FAA and cannot approve or deny projects. Results are informational only. COMPONENT STATUS DESCRIPTION Analysis parameters PASS Analysis time interval and eye characteristics used are acceptable 2-mile flight path(s) PASS Flight path receptor(s) do not receive yellow glare ATCT(s) N/A No ATCT receptors designated Default glare analysis parameters and observer eye characteristics (for reference only): • Analysis time interval: 1 minute • Ocular transmission coefficient: 0.5 • Pupil diameter: 0.002 meters • Eye focal length: 0.017 meters • Sun subtended angle: 9.3 milliradians FAA Policy 78 FR 63276 can be read at https://www.federalregister.gov/d/2013-24729 Page 1 of 7 SITE CONFIGURATION PV Array(s) Analysis Parameters DNI: peaks at 1,000.0 W/m^2 Time interval: 1 min Ocular transmission coefficient: 0.5 Pupil diameter: 0.002 m Eye focal length: 0.017 m Sun subtended angle: 9.3 mrad Site Config ID: 67775.11971 Methodology: V2 Name: North Array 1 Axis tracking: Single-axis rotation Backtracking: Shade-slope Tracking axis orientation: 180.0° Max tracking angle: 60.0° Resting angle: 60.0° Ground Coverage Ratio: 0.5 Rated power: 6807.0 kW Panel material: Smooth glass with AR coating Reflectivity: Vary with sun Slope error: correlate with material Vertex Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) 1 43.350006 -73.613639 337.04 20.00 357.04 2 43.350037 -73.611665 328.67 20.00 348.67 3 43.348929 -73.610957 324.73 20.00 344.73 4 43.348570 -73.610850 322.71 20.00 342.71 5 43.348305 -73.610442 321.77 20.00 341.77 6 43.346214 -73.610270 318.80 20.00 338.80 7 43.346198 -73.610807 322.99 20.00 342.99 8 43.345855 -73.610807 320.25 20.00 340.25 9 43.345871 -73.611193 322.76 20.00 342.76 10 43.345184 -73.611515 323.25 20.00 343.25 11 43.344841 -73.611815 323.07 20.00 343.07 12 43.344810 -73.612395 328.49 20.00 348.49 13 43.344107 -73.613553 325.51 20.00 345.52 14 43.344092 -73.614691 343.48 20.00 363.48 15 43.344794 -73.614712 349.11 20.00 369.11 16 43.346167 -73.612867 345.89 20.00 365.89 Page 2 of 7 Flight Path Receptor(s) Name: South Array 2 Description: Ground-mounted single axis tracking solar facility Axis tracking: Single-axis rotation Backtracking: Shade-slope Tracking axis orientation: 180.0° Max tracking angle: 60.0° Resting angle: 60.0° Ground Coverage Ratio: 0.5 Rated power: 6683.0 kW Panel material: Smooth glass without AR coating Reflectivity: Vary with sun Slope error: correlate with material Vertex Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) 1 43.327429 -73.605438 373.67 20.00 393.68 2 43.327367 -73.609515 360.78 20.00 380.78 3 43.326352 -73.609515 360.21 20.00 380.21 4 43.326352 -73.609150 363.78 20.00 383.78 5 43.325337 -73.609129 363.26 20.00 383.26 6 43.324729 -73.608871 370.08 20.00 390.08 7 43.324666 -73.608485 374.00 20.00 394.00 8 43.327226 -73.608635 364.53 20.00 384.54 9 43.327179 -73.608013 365.97 20.00 385.97 10 43.324635 -73.607970 379.76 20.00 399.76 11 43.324635 -73.607112 375.01 20.00 395.01 12 43.324978 -73.607112 376.24 20.00 396.24 13 43.324963 -73.606511 373.10 20.00 393.10 14 43.325447 -73.606339 375.37 20.00 395.37 15 43.325478 -73.605266 347.96 20.00 367.96 Name: Rwy 1 Description: Threshold height: 50 ft Direction: 358.0° Glide slope: 3.0° Pilot view restricted? Yes Vertical view: 30.0° Azimuthal view: 50.0° Point Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) Threshold 43.335766 -73.608710 320.77 50.00 370.77 Two-mile 43.306871 -73.607300 209.98 714.24 924.23 Page 3 of 7 Name: Rwy 12 Description: Threshold height: 50 ft Direction: 110.0° Glide slope: 3.85° Pilot view restricted? Yes Vertical view: 30.0° Azimuthal view: 50.0° Point Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) Threshold 43.341478 -73.618994 326.47 50.00 376.47 Two-mile 43.351367 -73.656395 326.93 760.23 1087.16 Name: Rwy 19 Description: Threshold height: 50 ft Direction: 178.0° Glide slope: 3.0° Pilot view restricted? Yes Vertical view: 30.0° Azimuthal view: 50.0° Point Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) Threshold 43.349344 -73.609205 323.71 50.00 373.72 Two-mile 43.378239 -73.610594 298.34 628.83 927.17 Name: Rwy 30 Description: Threshold height: 50 ft Direction: 290.0° Glide slope: 3.0° Pilot view restricted? Yes Vertical view: 30.0° Azimuthal view: 50.0° Point Latitude (°) Longitude (°) Ground elevation (ft)Height above ground (ft) Total elevation (ft) Threshold 43.337694 -73.605058 322.39 50.00 372.39 Two-mile 43.327806 -73.567660 268.75 657.09 925.84 Page 4 of 7 GLARE ANALYSIS RESULTS Summary of Glare PV Array Name Tilt Orient "Green" Glare "Yellow" Glare Energy (°) (°) min min kWh North Array 1 SA tracking SA tracking 0 0 20,790,000.0 South Array 2 SA tracking SA tracking 0 0 19,450,000.0 Total annual glare received by each receptor Receptor Annual Green Glare (min) Annual Yellow Glare (min) Rwy 1 0 0 Rwy 12 0 0 Rwy 19 0 0 Rwy 30 0 0 Results for: North Array 1 Receptor Green Glare (min) Yellow Glare (min) Rwy 1 0 0 Rwy 12 0 0 Rwy 19 0 0 Rwy 30 0 0 Flight Path: Rwy 1 0 minutes of yellow glare 0 minutes of green glare Flight Path: Rwy 12 0 minutes of yellow glare 0 minutes of green glare Flight Path: Rwy 19 0 minutes of yellow glare 0 minutes of green glare Page 5 of 7 Flight Path: Rwy 30 0 minutes of yellow glare 0 minutes of green glare Results for: South Array 2 Receptor Green Glare (min) Yellow Glare (min) Rwy 1 0 0 Rwy 12 0 0 Rwy 19 0 0 Rwy 30 0 0 Flight Path: Rwy 1 0 minutes of yellow glare 0 minutes of green glare Flight Path: Rwy 12 0 minutes of yellow glare 0 minutes of green glare Flight Path: Rwy 19 0 minutes of yellow glare 0 minutes of green glare Flight Path: Rwy 30 0 minutes of yellow glare 0 minutes of green glare Page 6 of 7 Assumptions 2016 © Sims Industries d/b/a ForgeSolar, All Rights Reserved. "Green" glare is glare with low potential to cause an after-image (flash blindness) when observed prior to a typical blink response time. "Yellow" glare is glare with potential to cause an after-image (flash blindness) when observed prior to a typical blink response time. Times associated with glare are denoted in Standard time. For Daylight Savings, add one hour. Glare analyses do not account for physical obstructions between reflectors and receptors. This includes buildings, tree cover and geographic obstructions. Several calculations utilize the PV array centroid, rather than the actual glare spot location, due to V1 algorithm limitations. This may affect results for large PV footprints. Additional analyses of array sub-sections can provide additional information on expected glare. The subtended source angle (glare spot size) is constrained by the PV array footprint size. Partitioning large arrays into smaller sections will reduce the maximum potential subtended angle, potentially impacting results if actual glare spots are larger than the sub-array size. Additional analyses of the combined area of adjacent sub-arrays can provide more information on potential glare hazards. (See previous point on related limitations.) Glare locations displayed on receptor plots are approximate. Actual glare-spot locations may differ. Glare vector plots are simplified representations of analysis data. Actual glare emanations and results may differ. The glare hazard determination relies on several approximations including observer eye characteristics, angle of view, and typical blink response time. Actual results and glare occurrence may differ. Hazard zone boundaries shown in the Glare Hazard plot are an approximation and visual aid based on aggregated research data. Actual ocular impact outcomes encompass a continuous, not discrete, spectrum. Refer to the Help page at www.forgesolar.com/help/ for assumptions and limitations not listed here. Page 7 of 7