Whether you call it a pipe mount, post mount or mast mount, a solar pole mount clamps to the outside of a round pipe. So the number that matters is the pipe's outside diameter (OD), and that's where most people get tripped up.
Nominal pipe size vs. outside diameter
Pipe is sold by a nominal size that doesn't match any measurement you can take. A "2 inch" pipe is actually about 2 3/8" across the outside. Use this chart to match your pipe to the right mount.
| Nominal pipe size | Outside diameter (OD) | Mount that fits |
|---|---|---|
| 2" | 2 3/8" (2.375") | 2" array top cap, and the horizontal cross pipe for every mount |
| 2.5" | 2 7/8" (2.875") | 2.5" array top cap |
| 3" | 3 1/2" (3.5") | 3" top of pole mount |
| 4" | 4 1/2" (4.5") | 4" top of pole mount |
How to measure your pipe
- Calipers or a ruler: measure straight across the outside of the pipe end.
- Tape measure: wrap it around the pipe to get the circumference, then divide by 3.14 to get the OD.
Example: a circumference of about 11" divided by 3.14 is about 3.5", which is 3" nominal pipe.
Schedule 40 vs. schedule 80
Schedule is the wall thickness. For the same nominal size, schedule 40 and schedule 80 have the same outside diameter. Schedule 80 just has a thicker wall, so it's heavier and stiffer. Because our mounts clamp to the outside of the pipe, both fit.
Galvanized, black or oilfield pipe?
- Galvanized pipe has a zinc coating that resists rust outdoors, and it's easy to find at hardware stores.
- Oilfield pipe is common in rural areas and often inexpensive. It works as long as the OD matches the chart.
- Black steel pipe fits the same way, but plan to paint it to protect it from rust.
Which mount do you need?
- One pole, up to 6 panels: a top of pole mount on 3" or 4" ground pipe, holding a 2" horizontal pipe.
- A ground array on 2-20 poles: array top caps on 2" or 2.5" ground pipe, with 2" cross pipe between them.
Still deciding? See how many panels fit on one pole.
