In a solar project budget the steel structure is priced by tonnage, so the first question is always the same: how many tons of steel does 1 MW need? There is no single number — it depends on module power, table layout, the site's wind and snow load, the soil and the sections chosen. The method, however, is simple, and once set up it can be repeated for any project in minutes.
The method
1. Table power: modules per table × module power. 2. Tables per MW: 1,000,000 Wp ÷ table power. 3. Steel per table: for each member, count × length × weight per metre (kg/m) — piles, rafters and chords, purlins and rails. 4. Connections and secondary members: add an allowance for brackets, braces and splices (10% in the example below). 5. Total: table weight × number of tables = tonnage per MW.
Take the weights per metre from the tables on our solar steel profiles pages or from our weight calculator.
Worked example: a 2V fixed-tilt table
The assumptions are an example and change with every project: 600 Wp modules; a 2V × 14 = 28-module table (16.8 kWp); 4 frames × 2 = 8 piles per table, 3.5 m long on average; a 4.8 m rafter per frame; 4 purlin rows of 16.5 m along the table. Weights per metre are computed with an inner bend radius equal to the thickness.
| Member | Section and calculation | Per table (kg) |
|---|---|---|
| Piles | C150×60×20×2.5 (5.76 kg/m) · 8 × 3.5 m | 161 |
| Rafters | C120×50×20×2.5 (4.78 kg/m) · 4 × 4.8 m | 92 |
| Purlins | C100×50×15×2 (3.40 kg/m) · 4 × 16.5 m | 224 |
| Connections and secondary (+10%) | Brackets, braces, splices | 48 |
| Total | ≈ 525 |
The result — and what moves it
1 MWp needs 1,000,000 ÷ 16,800 ≈ 60 tables: 60 × 525 kg ≈ 31.5 tons — about 31 kg/kWp in this example. Bolts, nuts and module clamps are not included.
Wind and snow load: in high-load zones sections and gauges grow, and edge and corner tables weigh more than interior ones.
Table layout: 1V layouts need more piles per MW; 2V uses fewer piles, each carrying a larger moment.
Soil: soft ground means longer piles; on-site pull-out tests remove unnecessary length.
Steel grade and section efficiency: S420GD–S450GD allow a thinner gauge; efficient sections such as a sigma pile or lapped Z purlins carry the same load with less steel.
Module power: higher module power puts more kWp on the same table, lowering kg/kWp.
Trackers: on single-axis trackers the posts, torque tube and rails form a different tonnage structure, usually calculated from the platform OEM's design.
From tonnage to cost
Rough cost ≈ tonnage × steel price per kg + coating premium + processing (punching, cutting) + fasteners + packing and freight + installation. The price per kg is driven mostly by the coil (hot-rolled steel) market; coating type and class also move it — a more durable coating usually pays for itself in service life and maintenance. Freight and installation depend on the site and the installer.
To get tonnage and price together for your own project, send the table layout, module data and site location through our quote form; we size the sections to your site loads and quote line by line.