IS 875: Indian Wind & Snow Load Standard for Solar Structural Design

Definition

IS 875 is the Indian Standard for design loads (other than earthquake) for buildings and structures. Part 3 covers wind loads — the primary reference for solar PV structural design in India alongside IS 800 (steel) and IS 456 (concrete).

IS 875 Parts

Part	Loads
1	Dead loads
2	Live loads
3	Wind loads (most relevant for solar)
4	Snow loads
5	Special loads

Wind Design

Basic wind speed × terrain category × topography × importance × structure factor = Design wind pressure

Terrain categories: 1 (exposed) to 4 (sheltered). Topography factor for hills, ridges.

Why This Calculation Matters for Solar

A solar mounting structure — whether a pile foundation driven ground-mount table or a rooftop rail system — has to survive the highest wind pressure its site will realistically see, without over-building the steel and driving up cost per watt. IS 875 Part 3 is what turns “this site is in a cyclone-prone coastal district” into an actual design number: a basic wind speed from the map, scaled by how exposed the terrain is, how hilly the topography is, and how critical the structure is, to arrive at a design wind pressure. That pressure then feeds into member sizing under IS 800 for steel and into the foundation loads a structural engineer certifies for CEIG approval. Skipping or under-specifying this step is one of the more common reasons structural calculation packages get sent back during review.

Key Takeaways

IS 875 = Indian structural load standard (Part 3 = wind, most relevant).
Solar ground mount and rooftop wind design in India references IS 875.
Basic wind speeds: 33–55 m/s across India.
Companion to IS 800 (steel) and IS 456 (concrete).
Required for CEIG-stamped structural calculations.

For a full walkthrough of the wind-load workflow this glossary entry summarizes — zone selection, terrain and topography factors, and how the numbers carry through to a mounting structure — see IS 875 Part 3 wind load calculations for Indian solar mounts. If your projects also cross into US markets, ASCE 7-22 wind load for solar rooftops covers the equivalent US methodology side by side with the Indian approach. Once the loads are defined, STAAD Pro for solar structures shows how they get modeled and analyzed, while SAP2000 vs STAAD Pro vs manual calculations helps decide which analysis method fits a given project’s size and lender requirements. For the downstream approval step, the CEIG drawing approval process in India walks through what state electrical inspectorates expect from a structural package built on IS 875 loads.

Frequently Asked Questions

5 commonly searched questions about IS 875.

What is IS 875?

Indian Standard for design loads for buildings — Part 1 (dead), Part 2 (live), Part 3 (wind), Part 4 (snow), Part 5 (special). Used for solar PV structural design in India.

What design wind speed does IS 875 use?

Basic wind speed map of India: 33 m/s (coastal) to 55 m/s (most of India). Coastal cyclone-prone regions: 50–55 m/s. Updated periodically.

Is IS 875 equivalent to ASCE 7?

Conceptually similar — both prescribe wind, snow, seismic load methodologies. IS 875 (India) vs. ASCE 7 (US). Numerical values and coefficients differ.

Latest IS 875 edition?

IS 875 (Part 3): 2015 (wind). Periodic revisions. Engineers must reference the current edition for CEIG submissions.

Does IS 875 apply to rooftop solar as well as ground-mount?

Yes. Rooftop arrays are checked against IS 875 Part 3 wind pressures too, but the relevant exposure and topography factors are usually different from a ground-mount site — rooftop mounting structures also need to account for the building's own aerodynamic effects, such as parapet shielding and roof-edge suction zones.