best practices for managing commercial and industrial rooftop solar installations
TRANSCRIPT
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q This webinar will be available afterwards at solarpowerworldonline.com & email
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Before We Start
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Meet your Speakers Jeremy Taylor Product System Engineer - Started in early grid tied market in 2002 as an
Installer - Became NABCEP certified in Installation in 2007 - Worked on the Engineering aspects for Developers,
EPC’s, Manufacturers, and as a Design Consultant for over 5 years
- At SunModo supports project implementation and product development
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Meet your Speakers
Brandon Gwinner Account Executive - Construction and Sales for over 15 years - SunModo brand representative for over 5
years - OSEIA board of Directors
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Founded in 2008 SunModo means “The Way of the Sun” HQ: Vancouver, Washington Culture of Innovation: 15 patents and growing Differentiator: Complete line of racking solutions for roof & ground mount systems with support/consult, as needed, engineering model Mission: Drive down the total cost of solar system Vision: Accelerate the adoption of affordable clean energy technologies worldwide
OUR STORY
OUR FOCUS THE PROFESSIONAL INSTALLER
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• Due Diligence: Costing, Warranties, Structural Assessment
• Contract, Design, Engineer, Procure, and Build
Course Overview: Commercial & Industrial (C&I) Low Slope Roofs
THE NEXT GENERATION IN SOLAR RACKING
OUR RACKING SOLUTIONS
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• ProForma: early costing, finance assumptions, modeled performance, billing scenarios • Due Diligence: membrane warranty/maintenance, layout fit with aisles and obstructions, and
structural feasibility (full structure weight <10% & member additional capacity) • Structural Engineering: Modeling of racking in wind, snow, and seismic, with building checks • Process Methodology: Development revisions (ROM), submittals (Bid, Permit, &
Construction), procurement (BOM), and Project Scheduling/Staging • Installation Best Practices
Commercial and Industrial (C&I) Low Slope Roofs
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Due Diligence: Best Practice for C&L Low Slope Roofs
Flat Roof Solutions
• ProForma model based on real site specific data (can vary 50% in racking or ~10% of project) • Preliminary Assessment: satellite imagery, photos, and building plans w/ framing dimensions • Structural feasibility assessment for contract is prudent
• Attachment member point loads (up/down) is an easy place to start • Additional capacity in building framing structure
• Pricing typically lasts 90 days (and NET60 to pay) • Commercial projects 6-12 months: ROM @ Contract • Preliminary BOM for Bids and final BOM for build • Engineering after contract
• Rests on preliminary costs and feasibility specs • Avoid structural retrofit. Can push over budget • Be flexible – don’t over fill or neglect spacing • Cost safe assumptions and then value engineer
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Design Iterations: How to minimize rework and delays
Flat Roof Solutions
• Assume middle model of module and check manufacturer’s availability forecast • Module frame dimensions should be interchangeable – more risk with odd sizes • Assume comfortable string size for module changes and layout accordingly w/o split
strings • Mechanical simplicity – modularity in standard, mechanical–structural, optimized detail • Use concept, schematic, and design development phases to evolve CD’s effectively • Stanchion/Flashing count reduction with longer rows and optimized spans • Electrical capacity sizing should come first, but the details should follow structural design
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Roof Warranty Concerns
Flat Roof Solutions
• Critical to consider the building owners documents with roof manufacturer and roofer in loop • If warranty is in place, recommend and obtain preliminary approval of attachment detail • Sub scoping to roofer is key – roofer last pass through is recommended • If no warranty then a lifecycle assessment of roof is necessary • System removability or reroof considerations – Elevated post design w/ enough clearance • Coordinate the scope delineation and phased construction for clarity
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Single Row Tilt-Up (SRTU) • Max kWh/kW and lightest attached (expensive modules or higher investor
hurdles) • Adjustable tilt legs provides tailored array angle up to 40 degrees • Low point load system ideal for light roof structure application (portrait or even
shared rail) • Loads work on older buildings • No seismic or skid issues
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Mounting options (flush-ballasted, elevated and tilt-up) - Ventilation and performance - Cost-Benefit analysis
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C&I Preliminary Design Decisions
Flat Roof Solutions
• Pay for tilt in wind uplift, post height, and lost roof space/project size • Make decision from LCOE (max kWh/kW) or NPV (max capacity) customer
specific • value engineer: cost increase vs. energy gain to find law of diminishing
returns • typically going to need to see three points to see the break or value
balance
$3.20 $3.30 $3.40 $3.50 $3.60 $3.70 $3.80 $3.90 $4.00 $4.10
100 99 98 97 96 95
System Price to Energy
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• Installed over some roof obstructions (more adaptable coverage to crowded roofs) • Easily customizable and adjustable for any tilt designed (even mixed pitches) • Provides valuable shade for roof and AC units (increase longevity of neighbor systems) • No system removal needed for roof maintenance (hard flashing and counter flashing) • 30-50% more kW on cluttered roofs with tall parapets (best long term value and performance)
SunBeam: System Overview
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SunBeam: Elevated Design • Elevated above fan units (non-vertical), HVAC ducts, vents, piping and conduits • Allows maintenance under the racking: preset posts and provide reroofing ease • Best practice: check with AHJ for preliminary approval
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SunBeam: Components
PostCap SunBeamRail PipeClamp AngleMount Solidbaseandaluminumpost
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SunBeam: Configuration • Critical dimensions for inter-row or parapet setback • Ideal to coincide with required walkways • Share attachments with long rows • Repeatable detail per building optimization
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SunBeam: Post Spacing • Configuration for point load • Vs. Roofing cost reduction
I-Beam Span Tables
E-W: I-Beam Spans, 30 deg tilt, 115 mph, 30 ft elevation, Exposure B, deflection limit = Length of span:
No Snow, Exp B
25 PSF Snow, Exp B
25 PSF Snow, Exp C
2L 144 126 120 3L 126 108 108 4L 120 96 90 2P 120 102 102
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Triangle BoxBeam: Configuration • 30’ spans: single row is possible with only four posts • 12-18’ spans: 3up configuration to minimize posts
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Side Mount Post Cap (SMPC): Configuration • 6’ x 6’ post layout is typically cheaper with re-roof • Depends on framing or slab thickness
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Shared Rail: Configuration • Can be tilted up with additional lateral support • Need to check module attachment locations and engineer with frame strength
values
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Structural Engineering (S-PE Stamp for Permit)
Flat Roof Solutions
• Wind zone – 100mph is lowest under ASCE 7-10, 110, 120, 140 • Snow loads – 0-40psf • Seismic – I, II, III • Exposure category- B, C, D, E, F • Wind KZT factor – topographical adjustment maps • Occupancy type – A (assembly), B (commercial), D (Industrial), E
(emergency), F (shop), H (Housing), M (merchant), R (residential), S (storage), & U (utility)
• Importance factor – adjustments based on occupation capacity • Roof zone – I middle, II edge, III corners (factors accordingly) • AHJ’s code cycle - ASCE 7-05, 7-10, 7-16 (different methods) • Product/fastener testing values (pounds pull out, shear or pascals) • Tributary Area (Array surface to each load path) • Spans and supporting members
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Structural Best Practice: How to avoid revisions and delays • Preliminary S-PE Feasibility Report on building loading and member capacity • Full roof survey of obstructions, parapet, and member locations for
contractual fit • Get a sense of what is possible and allow for flexibility in attachment or
fastener frequency • Get design past concept with Interconnection and mechanical details prior to
final S-PE • Permit and BOM post stamp • Then finish electrical detailing string layouts for construction
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Roof Framing
Flat Roof Solutions
• Avoid structural retrofit by choosing right solution • Attach correctly – 2 hole standoff • Attachment frequency often dictates racking type
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C&I Preliminary Design-Engineering Decisions
Flat Roof Solutions
Adder: Roofing costs affecting warranted “per attachment cost” Drivers: Heat process, multiple layers, site elements, and scope disruption Factor: More cost per attachment: lean to less attachments Adder: Limited structural capacity- overall and point load Drivers: Engineered truss (steel web or wood), barrel, TJI, concentrated snow loads, wider spacing Factor: Less Attachments = More expensive span member Adder: Building member attachment type Drivers: Epoxy concrete anchors, locating on post tension, hardware per attachment, frequency Factor: More labor at each attachment Adder: Structural Retrofit Drivers: required support and distribution of wider spans Factors: Biggest Project Adder
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Procurement Strategy & Construction Schedule
Flat Roof Solutions
• Assume model of module in middle of the spectrum for availability forecast • Preliminary ROM for pricing +/-10% pre-engineering (+/- 1% of project cost) • Flexibility means “attachment spacing TBD” but feasible (tend to safe side and
then reduce) • After Engineering – firm up BOM and order NET60 means the permit in hand
with progress payment upon delivery (JIT Delivery – Just in time for task) • Schedule mechanical installation accordingly well before module arrival • Series/Parallel crews seems to work well on medium or larger projects – Work
Flow! • Mechanical in first, get way ahead • Roofers in soon after mechanical (or posts only) and final pass after heavy
work • Electrical can attach modules and wire at same time, then drop back
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Thermal Expansion
-40-20
020406080
100120140
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
Tem
pera
ture
°F
Variable Gap Distance in inches
Expansion Gap (range over temperature)
Extreme@40'/Mild@80'
Moderate@40'
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Pitch Pocket: Installation - Could be up to 12” deep - Get down to flat structural member (perpendicular upward)
Cut Scrape Drill
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Pitch Pocket: Epoxy Anchor Setting
1. Drill – Drill hole to specified diameter and depth.
2. Blow – Remove dust from hole with oil-free compressed air for a minimum of 4 seconds. Compressed air nozzle must reach the bottom of the hole.
3. Brush – Clean with a nylon brush for a minimum of 4 cycles. Brush should provide resistance to insertion. If no resistance is felt, the brush is worn and must be replaced.
4. Blow – Remove dust from hole with oil-free compressed air for a minimum of 4 seconds. Compressed air nozzle must reach the bottom of the hole.
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Pitch Pocket: Set Anchor and Plate • Laser/String align for Beam from end posts (minor adjustability in post
cap) • Washer will keep epoxy on plate only so it can be tightened
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Pitch Pocket: Roofing Scope • Boot is cheap, flexible, but can crack
and require disassembly for replacement
• High End - liquid urethane, polyglycol rubber, and polyurethane foam
• Best Practice: metal flashing/counter flashing
• Elevated for run off (no pooling at post!)
• Stabilize post with additional hardware if required for re-roof
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Lightning Protection
Lightning Strike Myths • Hits tallest object • Grounded tower more likely to be hit Lightning Protection Truths • Lightning hits ungrounded/charged objects • Strikes when charge needs equalization (Standby
then Surge) • Auxiliary Electrode if over 100’ from Main Electrode
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Rooftop Array – Grounding Clarity PV System Grounded or Ungrounded?• Has a bonded conductor (+/-, or neutral) Finer array grounding points: • System Grounding GEC required?
• One bond point per isolated system • Isolated MicroInverters: SMA, ABB, APS • Racking holding transformers
• Ungrounded System requirements? • Enphase, SMA-TL = Transformer-Less (TL) • More important that system be bonded to detect faults (especially if there are no
MLPE) • More important to honor requirement of EGC only and PV-Wire in raceway
• Auxiliary Electrode is advised in lightning prone areas for rooftops • Dissipating static charge to reduce lightning possibility • Path for lightning to ground in rare cases • But must be bonded to common ground to NOT draw lightning surge
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UL 2703 & NEC 690 Article Review • Safety – faulted equipment or wiring
• NEC 690.43 Equipment Bonding • NEC 690.35 Ungrounded Systems – Metal jacketed wiring, Raceway
• NEC 690.45 Size of Equipment Grounding Conductors (EGC 250.122) • NEC 690.46 Array EGC – wire protection from physical damage w/ exception for under rack
• NEC 690.48 Continuity of EGC- removal with jumper (advantage of our racking) • Zero potential system reference
• NEC 690.41 System Grounding – Ungrounded, 2 Wire, 3 Wire • NEC 690.42 Point of Grounding Connection – bond through GFPD (before fault)
• NEC 690.47 Grounding Electrode System – System and/or Array Electrode • NEC 690.49 Continuity of GEC- irreversible or listed permanent connection
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What is imparted by UL 2703 UL2703 racking bonds all equipment as EGC (rated for 30A at every pin-clamps/2per module) SunModo UL2703 racking is also a GEC (rated 60A or more Splice, Lug, and T-Bolt itself) Functionality Notes: • Dual pins on clamps Per NEC 690.43 (E ): ensures removing a module doesn’t break the continuity • Bonded Splices makes EGC for NEC 690.43(C ) with each continuous row • SunModo Lugs were tested in Short Circuit w/ 1520A for 6seconds (#6AWG GEC 1/0 Conductors) • Serrated ¼” T-Bolt for MicroInverters (Equal size to #6AWG for GEC or array electrode)
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SERVICES • Assembly Drawings for Projects • Wet Stamped Engineering Available • Configuration Tool and Calculators • Custom Racking Solution • Superior Technical Support
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Engineering & Technical Support
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Catalog, Manuals, Guides, and Appl Notes • Roof Attachments (Comp, Metal, and
Tile) • Pitched Roof Systems (UL 2703 Racking) • Flat Roof Tilt Up Systems • EZ SunBeam Roof Systems • EZ SunBeam Ground and Foundations
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Online Resources
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Questions?
Brandon Gwinner-Account Manager [email protected]
Jeremy Taylor- Product System Engineer [email protected]
For more information, visit our website or call www.sunmodo.com (360) 844-0048
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q This webinar will be available at solarpowerworldonline.com & email
q Join the conversation at #SolarWebinar
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