Solar Sigma Pile — Rib-Stiffened Post

A sigma section is a lipped C-profile whose web is given two inward steps — seen end-on it resembles the letter Σ. The steps act as longitudinal stiffeners running the length of the web, breaking the wide, thin web plate into shorter elements.

The result is a web that resists local buckling better under load: more of the section works effectively, giving higher bending capacity than a C-section of the same gauge and similar weight. The stepped web also adds stiffness while the pile is being driven.

High wind and snow load: when the moment per pile rises, the sigma section adds capacity without adding gauge.

Large 2V tables and wide pile spacing: carrying a bigger table on fewer piles raises the load per pile — where the sigma section pays off.

Soft ground: when uplift capacity requires deeper driving, the total length and bending increase; the sigma's stiffness and grip help.

Cutting tonnage with thinner gauges: combined with high-yield S420GD–S450GD grades, total steel tonnage can come down. Compare with the C-pile.

Because sigma geometry (step depth, inclined leg, lip) varies from one design to the next, there is no single standard weight table. In roll forming the weight is found most accurately from the developed strip width: strip width (mm) × thickness (mm) × 7.85 ÷ 1000 = kg/m.

For example, a sigma section with a 300 mm strip at 2.5 mm weighs about 5.89 kg/m. Send us your drawing for the exact figure.

We roll sigma piles in grades from S350GD to S450GD from Zn-Al-Mg (ZM120–ZM430) or galvanized (Z275–Z600) pre-coated coil. Connection holes and adjustment slots are punched in-line in the same pass as the forming — no drilling on site. Coating selection is covered in our Zn-Al-Mg guide.

Some single-axis tracker platforms use sigma or similar stiffened sections as posts; others specify W-beam piles. The platform design belongs to the tracker OEM — we manufacture to the stated section, tolerance and coating. Because we make our own tooling, a platform-specific sigma geometry goes to first article quickly. More on tracker steel structures.