You’ve seen “IS 875 certified” on solar structure brochures. You may have been told your installer’s structure is IS 875 compliant. But if you can’t explain what IS 875 actually means, you can’t evaluate whether that claim is meaningful or marketing.
This article explains — in plain language — what IS 875 covers, what compliance actually requires, and why it should be non-negotiable in any solar structure you purchase in India.
What IS 875 Is
IS 875 is the Bureau of Indian Standards code of practice for design loads (other than earthquake) for buildings and structures. It is published in five parts, of which Part 3 — Wind Loads — is the relevant section for solar mounting structures.
IS 875 Part 3 defines how structural engineers in India must calculate the wind forces acting on any structure, including solar arrays. It maps the entire country into wind zones based on historical meteorological data, assigns a design wind speed to each zone, and provides a methodology for calculating the actual pressure the wind exerts on a structure at a specific height, terrain exposure, and geometry.
This is not a pass/fail test. It is a design methodology. An IS 875-compliant solar structure is one that has been structurally designed and verified using this methodology — meaning the steel members, connections, and foundations are sized to withstand the design wind forces for the specific installation location.
India’s Wind Zones: What Your Location Means
IS 875 Part 3 defines basic wind speeds across India in metres per second. The key values for South India and major solar markets are:
Hyderabad (Telangana): 44 m/s basic wind speed — Wind Zone III
Vijayawada, Guntur (AP): 44 m/s — Zone III
Visakhapatnam, Coastal AP: 50 m/s — Zone IV
Chennai: 50 m/s — Zone IV
Cyclone-prone coastal strips: 55 m/s — Zone V
These are basic wind speeds. The actual design wind pressure on a specific structure is higher, modified by factors for height above ground (taller structures face higher wind speeds), terrain category (open land faces more wind than built-up urban areas), local topographic effects, and the structure’s geometry.
A 10-degree tilt solar array at 5 metres height in open terrain near Visakhapatnam faces very different design wind pressures than the same array in a sheltered industrial compound in Hyderabad. IS 875 compliance means the structure has been designed for the actual conditions at your site — not for a generic average.
What “IS 875 Certified” Should Mean in Practice
When a solar structure manufacturer says their structure is IS 875 compliant, they should be able to provide:
A structural design report prepared by a qualified structural engineer that documents the wind load calculations using IS 875 Part 3 methodology for your specific site — with the location, terrain category, height, and tilt angle used in the calculation clearly stated.
Material specifications confirming that the steel used meets the minimum grade required to carry the calculated loads (IS 4923 for structural hollow sections is the standard reference).
A drawing set showing member sizes, connection details, and foundation specifications derived from the wind load analysis.
If a manufacturer claims IS 875 compliance but cannot produce a site-specific structural design report, the claim is decorative. A brochure printed with “IS 875” means nothing without the engineering behind it.
The Wind Load Certification Checklist
Before accepting any solar structure, ask your supplier to confirm the following:
Has a structural design calculation been prepared specifically for this installation site — with the correct wind zone, terrain category, and installation height?
Does the design report reference IS 875 Part 3 (the most recent edition)?
Are the steel member sizes and wall thicknesses in the fabricated structure consistent with what the design calculation specified?
Has the foundation design (anchor bolt size, embedment depth, or concrete footing dimensions) been calculated to match the wind uplift and overturning moment from the IS 875 analysis?
These questions take less than five minutes to ask. They are the difference between a structure that survives the next cyclonic event and one that doesn’t.
Why This Matters More in South India
South India — particularly coastal Andhra Pradesh — is one of the most solar-productive regions in the country and simultaneously one of the most demanding structurally. The Bay of Bengal generates cyclonic systems that make landfall regularly along the AP and Odisha coastline, delivering wind gusts well above basic wind speed values during cyclone events.
The combination of high solar irradiance and high structural demand makes the AP coast simultaneously one of India’s best solar markets and one that punishes under-engineered structures most severely. Projects installed near Visakhapatnam, Kakinada, Nellore, and Ongole with structures not designed for Zone IV or V wind loads represent a genuine risk.
Vlux’s Approach to Structural Certification
Every Vlux solar mounting structure is designed to IS 875 Part 3 for the specific installation site. Our engineering team prepares a structural design report for every project — not a generic certification statement, but a site-specific calculation that our customer receives as part of the project documentation package.
This documentation matters not only for structural integrity but for insurance purposes, net metering approvals in some DISCOMs, and any future due diligence on the asset if it is refinanced or sold.
IS 875 is not a checkbox. It is the foundation of a structure’s structural integrity claim. Demand the documentation that proves it.
