FX MOUNTING SYSTEM ENGINEERING & DESIGN GUIDE Version 0.
Contents 1.0 OVERVIEW OF FX SYSTEM ................................................................................................ 3 2.0 DEFINE SITE CONDITIONS & MODULE BEING USED .................................................. 3 2.1 Environmental Considerations .............................................................................................. 3 2.2 Roof Considerations.............................................................................................................. 4 2.
1.0 OVERVIEW OF FX SYSTEM The IronRidge FX Mounting System is a rail-less system for mounting solar modules on composition shingle pitched roofs. At the heart of the system is the Mount FX, which both supports and electrically bonds modules. The innovative grip design of the Mount eliminates the need for traditional clamps and associated steps to tighten them as well as setting a mount and gripping a module, speeding up installs.
Exposure Category Exposure category refers to the way obstacles protect buildings and the structures on top of them from the force of wind storms. Therefore, based on your setting (urban, rural, or on flat unobstructed terrain), you will design to one of the following Exposure Categories. The majority of buildings in urban areas have an exposure category B.
2.4 Predesign Worksheet Tip! Before starting design, make sure you that you have collected all the relevant information in the table below.
3.0 DESIGN 3.1 Define Roof Zones (RZ) Roof Zones are determined based on ASCE 7-10 (see Chapter 30). • In most residential applications, a = 3ft.
3.2 Determine Maximum Allowable Spans & Cantilevers Definitions Span: The distance between two adjacent Mounts, measured at the center of the hanger bolt. Cantilever: The section of a module extending beyond a Mount. Use the Span Tables (Appendix A) to determine maximum allowable spans and cantilevers. • Maximum Span is a function of (5) factors: Wind Exposure Category, Wind Speed, Roof Slope, Roof Zone, and Module Orientation (i.e. portrait or landscape).
3.4 Place Mounts It is important to note that Mount spacing may be different on the south edge versus the north edge of a module based on Roof Zone. Therefore, it is important to make sure that RZs are properly determined prior to placing the mounts. Starting with the first row of modules, work your way left to right across the row, and then up the roof applying the Roof Zone Rules (3.4.1) until all Mounts have been placed.
3.4.1 Apply Roof Zone Rules Roof Zone 3 If any part of a module falls within RZ 3, all Mounts touching this module must follow a RZ 3 span/cantilever.
Roof Zone 2 – South Edge Only • If more than 25% of a module’s southern edge falls within RZ2, all mounts along the southern row of the module follow RZ2 span/cantilever Example: On a 30° roof, the southernmost row falls in Roof Zone 2. Roof Zone 2 – East and West Edges • Mounts touching the column of modules located (partially) in RZ 2, use RZ 2 spans. • Adjacent Mounts use RZ 1 spans.
Roof Zone 2 – North Edge If more than 25% of a module falls in Roof Zone 2, use RZ2 spans for all Mounts touching that module. 3.4.2 Mount Placement Check 1. Verify each module must have at least one Mount on its north (up-slope) edge and one on its south (down-slope) edge. 2. Any single module columns (orphan module) must have at least (2) Mounts per supporting edge.
3.5 Bridge Placement Bridges are placed at all East-West module junctions. Similar to the method used for placing Mounts, start with the first row of modules, work your way left to right across the row, and then up the roof until all Bridges have been placed. Note that co-locating Mounts and Bridges is OK. 3.5.1 Bridge Placement Check 1. Verify that each Bridge is located between (2) Mounts.
2. A Bridge is not required at an east-west junction if each of the modules being joined with a Bridge is within the cantilever requirement. For example, in the drawing below, Junction A does not require a Bridge. At Junction B, the module on the right is properly cantilevered, but the module on the left requires a Bridge to complete the span. Note: A Bridge may be necessary for electrical bonding, even if it is unnecessary for structural support (see Section 3.7 – Electrical Grounding). 3.5.
Therefore, in the image above, (3) pieces of Trim and (3) End Caps (2 Left and 1 Right) are appropriate Both of the two arrays in the image below are staggered. They both have modules with partiallyexposed southern edges. The designer can choose to omit partial pieces of Trim in such cases, based on the aesthetic benefit versus the cost of the part.
3.7 Electrical Grounding Every module must be electrically bonded. The FX system makes bonding simple through integrated bonding. • One Grounding Lug is required per continuous array. • The Grounding Lug attaches easily to any Bridge along the north edge of the array. • Each Bridge provides east-west bonding, but only along the south (down-slope) side. o FX can be installed without Trim, in which case the Bridges on the southern edge of the array can be turned around to provide east-west bonding.
3.8 Generate Bill of Materials (BOM) Once all Mounts and Bridges have been placed, count up each component to generate the BOM. Qty Req’d Component Mount FX Bridge FX North Bridge Thumb Screws Flash FX & Hardware Lug FX Trim FX Trim End Caps 4.0 Example Arrays Example 1 Using the rules outlined above, place Mounts and Bridges on the array shown. Assume all modules are in Roof Zone 1. Wind Speed 115mph Ground Snow Load 40 psf Exp.
For the given site conditions, maximum spans and cantilevers are as follows: Max Span Max Cantilever RZ1 65" 22" RZ2 65" 22" RZ3 65" 22" Therefore, for all Roof Zones, Mounts can be placed up to (4) rafters apart (16” x 4 = 64”). Bill of Materials Qty. Mounts 10 Bridges 2 Trim 2 Example 2 Using the rules outlined above, place Mounts and Bridges on the array shown. Assume all modules are in Roof Zone 1. Wind Speed 115mph Ground Snow Load 40 psf Exp.
For the given site conditions, maximum spans and cantilevers are as follows: Max Span (landscape) Max Canti. (landscape) Max Span (portrait) Max Canti. (portrait) RZ1 65" 22" 37" 12" RZ2 65" 22" 37" 12" RZ3 65" 22" 37" 12" Therefore, Mounts can be placed up to (4) rafters apart in landscape, and up to (2) rafters apart in portrait (16” x 2 = 32” < 37”). Bill of Materials Qty. Mounts 8 Bridges 3 Trim 1* *Note: only a single piece of Trim is called out for this array.
Example 3 Using the rules outlined above, place Mounts and Bridges on the array shown. First determine Roof Zones. Wind Speed 115mph Ground Snow Load 40 psf Exp.
• • • • (2) modules fall into Roof Zone 3. All Mounts touching these modules follow RZ3 spans. (3) modules along the north edge are >25% in Roof Zone 2. All Mounts touching these modules follow Roof Zone 2 spans. (2) modules along the east/west edges enter into Zone 2. Mounts touching these modules follow Roof Zone 2 spans. (1) module along the south edge is >25% in Roof Zone 2. Mounts touching this module follow Roof Zone 2 spans.
5.0 Optimizing Designs Design optimization will save the Installer both time and money. 5.1 Landscape is superior to Portrait In most scenarios, it is more efficient and cost effective to layout modules in landscape than in portrait when using the FX system. 5.2 Optimizing Components Example Array 3 illustrates optimization of Bridges based on 4.1.10. Structurally, the leftmost column in the array can stand on its own without any Bridges.
