Solar Panel Flat Roof Mounting System 15 degrees

Introduction

I was looking for a inexpensive way to mount my solar modules on a flat roof. I came up with a solution utilizing cheap lawn curbs aluminum extrusions and 3D printed holders. The lawn curbs weight down the modules and give lateral stability. Accordingly, you do not need to drill holes in your roof. You might use it in a rental situation because of its removable nature. 30x30mm aluminum profiles provide height to tilt the panels by 15 degrees for effective self-cleaning. 

To extend the life span of plastic parts under sunlight conditions it is recommended to print in black. The black pigment absorbs more ultra violet light slows down degradation of plastics. 

To mount one panel you need two assemblies. To mount two panels side by side you need three assemblies and so on. 

Bill of material

This is for one assembly. 

• approx. 250g black PETG (front and back part)
• Lawn Curb (Rasenbordstein) 
  • 100cm x 25cm x 5cm 
  • approx. 28kg
• Aluminum Extrusion
  • 30mm x 30mm
  • length: 260mm
  • slot: 8mm
  • B type
• Two Solar Clamps (end or middle)
  • clamp height according to your solar panels (here 35mm)
  • provided screws and nuts will be replaced
• T Bracket for Rear Side
  • 110x85x36mm slot 8 or similar
  • 3mm thickness or similar
• Fasteners
  • Front Holder
    • 2 pcs. 8mm Nylon Anchors / Wall Plugs
    • 2 pcs. 5x40mm Screw Pan Head Self Tapping DIN 7996
    • 2 pcs. M6 Washer 18mm DIN9021
  • Front Solar Clamp
    • 1 pc. M8x30 Hexagon Socket Head Cap Screw DIN 912 / ISO 4762
    • 1 pc. Sliding Hammer Nut Slot 8 M8 for B type 
  • Rear Extrusion
    • 2 pcs. 8mm Nylon Anchors / Wall Plugs
    • 2 pcs. 5x40mm Screw Pan Head Self Tapping DIN 7996
    • 2 pcs. M6x10 Hexagon Socket Countersunk Bolt  DIN 7991 / ISO 10462
    • 2 pcs. Sliding Hammer Nut Slot 8 M6 for B type
  • Rear Solar Clamp
    • 4 pcs. M8 Washer 16mm DIN125
    • 4 pcs. M8x18 Hexagon Socket Head Cap Screw DIN 912 / ISO 4762
    • 4 pcs. Sliding Hammer Nut Slot 8 M8
    • 1 pc. M8x30 Hexagon Socket Head Cap Screw DIN 912 / ISO 4762
    • 1 pc. Sliding Hammer Nut Slot 8 M8 for B type

Tools

• drilling machine with 8mm concrete drill bit
• screwdriver (cordless)
• pencil to mark drill holes
• folding rule 

Instructions

Print Holders

• PETG black
• at least 3 perimeters
• 90% adaptive cubic infill

Mount Front Holder

• use outward tongue of lawn curb for the front side
• place front holder centered and aligned to lawn curb edge as shown on right figure
• mark mounting hole positions with a pencil
• remove front holder temporarily
• drill two holes with ~40mm and insert nylon anchors
• mount front holder with two self tapping screws with underlaying 16mm washers

Mount Back T Bracket

• use inward tongue of lawn curb for rear side allowing drilling centered
• hold T bracket centered on rear side of lawn curb
• mark mounting hole positions with a pencil
• remove bracket temporarily
• drill two holes with ~40mm and insert nylon anchors
• mount T bracket with two self tapping screws

Mount Back Holder to Extrusion

• place 4 hammer nuts with M8 threads in each slot of the extrusion
• slide back holder part on extrusion until its end stop
• slide hammer nuts under mounting holes, one by one
• mount rear holder to extrusion by M8 washers and screws

Mount Extrusion to Curb

• place M6 screws into T bracket and screw on M6 threaded hammer nuts loosely
• slide hammer nuts into extrusion with pre-assembled screws facing in correct orientation 
• push extrusion down extrusion assembly and tighten M6 screws

Place and Align Mounting System

• place assembled mounting systems in a straight line on your flat roof
• with a folding rule place assembled curbs with a center to center spacing of:
  • solar panel length + spacing added by one solar clamp
• place 1 hammer nut with M8 threads in each holder (front and back)
• screw in solar holders loosly with M8 hex head screws

Mount Solar Panels

• place panel on two mounting assemblies
• align assemblies for panels to be straight and centered on front and back holder
• tighten M8 hex head screws on one side
• tighten second side after placing the next panel or having the last of the row

Disclaimer

This system is used in a low windspeed environment. The author is not responsible for any damage linked to this project. Make sure to check for suitability, weighting, architectural statics and wind loads before beginning your build.