Fasteners for Solar Structures

A solar module mounting structure stands in sun, rain and wind for decades, so its fasteners must resist both corrosion and loosening. This page lists the fasteners such structures usually need and how to choose them. JMIKS Fasteners supplies every item in the table below from Ahmedabad.

Fasteners Used in Solar Structures

SS 304, Hot Dip Galvanized or Zinc Plated?

• SS 304 has no coating to wear away. It suits module clamps, aluminium rails and joints that should stay clean. Use SS 316 on coastal sites and near chemical plants. Compare them in our SS 304 vs SS 316 guide.
• Hot dip galvanized (HDG) steel carries a thick zinc coat, typically about 50 µm on fasteners (ISO 10684). It is the usual finish for high tensile 8.8 bolts on a galvanized steel structure. HDG bolts need HDG nuts, which are tapped oversize.
• Zinc plated steel has a thin coat, usually 5 to 12 µm. It suits indoor and covered parts, not exposed outdoor joints.

Many project specifications ask for SS 304 module fixings and HDG high tensile bolts for the main structure. Always follow your specification.

Aluminium Rails and Galvanic Corrosion

When two different metals touch and get wet, the less noble one corrodes faster. Aluminium is less noble than stainless steel, but a small SS 304 bolt in a large aluminium rail is generally acceptable, because the attack is spread over the large aluminium area.

On coastal or very wet sites, installers often fit insulating washers or sleeves, such as EPDM or nylon, between the stainless steel and the aluminium. Keep copper parts away from aluminium, and keep each bolt, nut and washer in the same material.

Stopping Nuts from Working Loose

Wind makes modules and rails vibrate, and over time this can loosen nuts. Common fixes:

• Nylock nuts: a nylon ring grips the thread. Standard inserts are rated to about 120 °C, above the temperature a structure normally reaches.
• Spring washers: keep tension in mild steel and stainless steel joints. On high tensile 8.8 bolts tightened to a high load they add little, so rely on nylock nuts and correct tightening.
• Serrated flange nuts: the serrations bite into the surface and resist turning.
• Wedge lock washers (SS 304 / SS 316): for trackers and joints with heavy vibration.

Solar Structure Fastener FAQs

Which fasteners are used to fix solar panels?

Module clamps are usually fixed with SS 304 bolts, plain washers and spring washers or nylock nuts. The steel structure uses hot dip galvanized high tensile 8.8 bolts, nuts and washers, and the base uses J bolts, L bolts or anchor fasteners.

Is SS 304 good enough near the sea?

Where salt spray reaches the structure, SS 316 lasts longer, because its molybdenum resists chlorides. Use SS 316 bolts, nuts and washers together.

Can zinc plated bolts be used outdoors on a solar structure?

Not for exposed joints. The zinc layer is thin and wears away outdoors, so use hot dip galvanized or stainless steel fasteners.

How can solar modules be protected from theft?

Fix them with anti-theft bolts and security shear nuts. Once the top of the shear nut breaks off, neither part can be gripped with ordinary tools.

Get a Quote for Solar Structure Fasteners

Send your bill of materials or drawing, with sizes, grades and quantities. Message us on WhatsApp at +91 90333 11425 or use our enquiry form, and we reply within one working day. See the full range in our catalogue (PDF).