TOOLS · SOLAR MOUNTING HARDWARE
Solar Mounting Hardware: Fastener Charts and Selection Entry
Two things decide which chart you need: how the array is fixed to the roof, and the module frame thickness you measure on the module. The roof build-up picks the hanger bolt; the measured frame thickness picks the clamp. Everything else on the array — the bolt, the nut and the washers — follows the part it sits with.
This page gathers the solar mounting hardware charts that are live today: 2 families, 11 pages, 13 URLs. It routes you to the chart that answers your part, and it says what is not covered yet. It adds no new values — every figure comes from the family page that owns it, and those pages are linked from here.
Which chart answers your question
| The question in front of you | What decides the answer | The chart |
|---|---|---|
| How is the array fixed to the roof? | The roof build-up decides it: a timber purlin takes the wood thread, a steel purlin takes the self-drilling variant, and the profile above it decides the hook. | Hanger bolts for roof mounts → |
| Which clamp holds the module? | The frame thickness you measure on the module flange decides it — the clamp is named after the thickness it grips, and the end clamp and the mid clamp take the same band. | End and mid clamps by module frame thickness → |
One more thing is fixed across the whole clamp series: whatever the frame thickness, the paired bolt stays M8. The bolt, the nut and the washers are charted separately and linked below.
Two selectors: pick the roof fixing, count the clamps
Answer a few questions and the page answers from the charts it links to. Nothing below is typed in by hand: every figure is read from the family chart that owns it, or worked out from your own inputs. No email, no account.
Roof fixing selector
Which hanger bolt goes into your roof build-up, and what travels with it.
From your inputs
Bottom thread for the purlin material you picked: Lag thread — self-tapping into the timber purlin.
Parts that travel with it
- Flange nut
- Flange nut: across flats 13 mm, height 8 mm, flange diameter 17.9 mm.
- Flat washer
- Flat washer: outside diameter 16 mm, thickness 1.6 mm.
- Spring washer
- Spring washer: outside diameter 14.8 mm, thickness 2 mm.
These are supply dimensions for ordering rather than a standard-number claim: the hanger bolt and the EPDM washer are non-standard parts, so the drawing is the authority.
Values you can recompute calculated
- Washer bore, lower limit
- 8
- Washer bore, lower limit equals the nominal bolt diameter: 8 mm.
- Exposed machine thread, lower limit
- 8
- Exposed machine thread, lower limit equals the flange nut height: 8 mm.
Clamp counter
How many end clamps and mid clamps your array needs, from its layout.
Count from your layout
Clamps in total: 3.
- End clamps
- 2
- Mid clamps
- 1
Paired nut and washer sets: 3, one set per clamp.
Smallest clamp bolt length for the 38 mm band: 46.1 mm — frame thickness plus flat washer plus nut.
Geometric derivation and engineering convention, marked calculated: one mid clamp at every joint (modules per line minus one) and one end clamp at each end of every racking line. It is not a standard value, and no figure here is taken from any manufacturer or distributor quantity table.
All three counts come from the layout you enter. Rows, modules per row and racking lines per row are separate inputs on purpose: one fixed number would be wrong for every layout except the one it was written for.
Have the drawing or the layout?
Send the roof build-up, the array layout and the part list. We answer with the sizes, the paired parts and the supply programme for your project.
Copies the current selection and results as plain text. No account, nothing sent anywhere.
What this selector does not answer
The 5 items below wait on a production drawing, a batch inspection report or the project structural calculation. They are left out on purpose rather than estimated here.
- Which bolt size a given wind or snow load needs — that mapping waits on the pull-out and load test records from our production line.
- A number for the minimum embedment depth — the rule reads thread engagement count times the lag pitch, and neither factor is held as a value here, so the drawing decides it.
- A number for the pilot hole diameter — a supplier drawing value.
- A tightening torque number — it needs the property class off the drawing or the batch inspection report, and that source is not held here.
- A wind or snow verdict — the local load case and the spacing between fixings belong to the project structural calculation, not to a chart.
Solar mounting kit
Download the solar mounting hardware kit (2 PDFs)
Two full-range solar mounting PDFs — hanger bolts and module clamps — packed into one ZIP; enter your email to get it.
What a PV array needs, part by part
The parts that fix a module to a roof, and the chart that answers each one. A row marked as not covered yet is a gap in our own range rather than in the array — it is listed here so you know where to send the question.
| Part | What it does | The chart that answers it | Form |
|---|---|---|---|
| Roof hanger bolt | Carries the rail or bracket down into the roof structure: the wood thread into a timber purlin, the self-drilling variant into a steel one. | Hanger bolts for roof mounts | Made to drawing |
| End clamp | Presses the outer edge of the array onto the rail; it takes its load on one side only. | End and mid clamps by module frame thickness | Made to drawing |
| Mid clamp | Presses two adjacent modules onto a shared rail run; same band as the end clamp, different body. | End and mid clamps by module frame thickness | Made to drawing |
| Clamp bolt | Tightens the clamp onto the rail. In the clamp series we chart it is one size across the whole range. | Bolt size chart | Catalogue sizes |
| Hex nut | Closes the clamp bolt; across flats and height decide the socket and how much bolt length the joint uses up. | Hex nut weight chart | Catalogue sizes |
| Flat washer | Spreads the clamp load and keeps the nut off the anodised clamp body. | Flat washer weight chart | Standard number |
| Flange nut | The nut the rooftop hanger bolt is normally supplied with; the flange spreads the load without a separate washer. | Flange nuts, standard number | Standard number |
| Self-drilling screw | Fixes sheet and trim on the roof build-up where a drilled hole is not practical. | Self-drilling tapping screws, standard number | Standard number |
| Earthing and cable hardware | Bonding washers, earthing clips and cable cleats that carry continuity and hold the DC string in place. | Earthing and cable hardware | Not covered yet |
The order above is the order you meet them: first what carries the array down to the roof, then what presses the module onto the rail, then what pairs with the clamp, then the parts outside our current range.
Form: a standard number means the part is quoted against that number and the link goes to its page; made to drawing means it is a non-standard part cut to your drawing; catalogue sizes means the dimensions are charted and the standard number is confirmed with the order; not covered yet means we have no chart for it today.
Hanger bolts for roof mounts
The bolt that carries the load from the rail or bracket down into the roof structure, with the nut, the washer and the length that go with it.
Key specification
Sizes M8 / M10 / M12 · supply length 100–250 mm · wood thread and self-drilling variants
Wood thread for timber purlins and self-drilling for steel purlins. The exposed machine thread and the embedment are stated there as rules with their assumptions, not as tabulated numbers.
Every band in this family has its own page:
End and mid clamps by module frame thickness
The clamp that presses the module frame onto the rail, named after the frame thickness it grips.
Key specification
Frame thickness 30–45 mm · end clamp and mid clamp on the same band · paired bolt M8 across the whole series
One band per thickness. The grip height, the clamp body and the clamp spacing are set per project and are stated there as rules, not as tabulated numbers.
Every band in this family has its own page:
Clamp bolt torque: where the number comes from
A tightening value is not a property of the bolt alone. It depends on the property class of the bolt, on the friction condition of the joint, and on what the module maker and the clamp maker require for their own frame and rail. That is why neither chart on this page prints a torque value: for these parts the property class is a drawing value, and the standard that would give the mechanical properties is not held here.
T = K × F × d
To compute it you need the target preload F (from the property class and the clamp load the maker allows) and the friction factor K of the actual joint — not a nominal K.
So this page gives the method and the precondition rather than a number, and it does not republish a value from any maker's installation manual.
The K ranges and the method are on the bolt torque chart →Standards, non-standard parts, and what documents to ask for
3 parts on this page are quoted against a standard number, and the links below go straight to those pages. The solar parts themselves — the hanger bolts and the clamps — are non-standard: there is no national standard for them, so the drawing, not a number, is the specification.
- Flat washer · GB/T 97.1 →
Quoted against the standard number on the product page; the dimensions come from the in-repo fastener source and the chart linked above.
- Flange nut · GB/T 6177.1 →
Quoted against the standard number on the product page; the sizes are read as supply dimensions and confirmed with the order.
- Self-drilling screw · GB/T 15856.1 →
Quoted against the standard number on the product page; the length and the point are selected against the sheet thickness you are fixing.
What travels with the batch
Ask for the same three things on any of it: the material test certificate that comes with the heat, the reading of the standard it is issued to, and a receiving inspection against the drawing or the standard number before the parts go onto the roof.
- How to read a material test certificate →
What each field on the certificate means, and which fields you should be able to trace back to the heat.
- EN 10204 3.1 and 3.2 compared →
Which of the two inspection documents you are entitled to, and what changes when a third party issues it.
- Receiving inspection checklist →
The checks to run when a batch lands, in the order that catches a problem before the parts go up.
How to specify and ask
These are made-to-drawing and standard-numbered parts, so a price needs three things rather than a shopping cart:
- The drawing or the standard number, with the size, the length and the material as you need them.
- The quantity, as a project figure rather than a trial pack.
- The project location, because the roof build-up, the coastal or industrial exposure and the mounting system differ with it.
Downstream: the charts around these parts
Standard-numbered parts and their pages
- Flange nuts, standard number →
The nut a rooftop hanger bolt is normally supplied with, on its own product page.
- Flat washers, standard number →
The washer behind the clamp nut, on its own product page.
- Self-drilling tapping screws, standard number →
The self-drilling screw for sheet and trim, on its own product page.
General fastener charts these parts rely on
- Bolt size chart →
Width across flats, head height and thread length for hex bolts — the dimensions behind the bolt you tighten.
- Bolt torque chart →
The K-factor method and the friction ranges behind any tightening value.
- Wrench and socket size chart →
Which socket or spanner a given across-flats takes, including the sizes in between.
- Hex nut weight chart →
Across flats, height and unit weight per size, for costing a batch.
- Flat washer weight chart →
Outside diameter, thickness and unit weight, read from the same in-repo source the clamp chart uses.
What this page covers, and what it does not
Two families are live today and both are linked from this page — Hanger bolts for roof mounts: 3 · End and mid clamps by module frame thickness: 8 pages, 2 families, 13 URLs in all. That is everything this page can route you to right now.
Not covered yet
4 of them, listed so you know where to ask instead of guessing. No placeholder is shown for a chart that does not exist, and nothing is filled in to make the list look complete.
Ground-mount foundations
Piles, ground screws and base plates for ground-mounted arrays sit outside the two families on this page; they are quoted against the structural drawing.
Clamp body and rail dimensions
Grip height, jaw depth, rail section and wall thickness are drawing and project values, so the clamp chart states them as rules and does not tabulate them.
A tightening value for the clamp bolt
Set by the property class, the friction condition and the module maker's requirement, so it is worked out per project and is not published here as a number.
Earthing and cable hardware
Bonding washers, earthing clips and cable cleats are not charted yet; send the drawing and the array layout and we answer against it.
This page is the entry for the solar hardware charts, and it grows with them: as more families go live they are added here as real entries, not as placeholders before they exist.
Where the numbers on this page come from
Every figure on this page comes from one of the two family charts linked above, or is derived from the range those charts own. This hub holds no data table of its own, so nothing here needs a second source; the two charts and the in-repo fastener source are named below.
Sources
- Solar hanger bolt size chart — the source for the hanger bolt sizes and supply lengths on this page
- Solar clamp size chart — the source for the module frame thickness bands on this page
- In-repo metric thread and fastener source — the source for the paired bolt, nut and washer dimensions
- Non-standard parts and manufacturer installation manuals — fixed per project drawing and vendor document; no generic values are listed here
On the two linked family charts every value is traceable row by row; non-standard parts and vendor documents are fixed per project and are not used as value sources here.
Cite this chart
YAXIIO. Solar Mounting Hardware: Fastener Charts and Selection Entry. https://www.yaxiio.com/en/tools/solar-mounting-charts (accessed 2026-10-29).
Free to cite and embed — attribution required: “YAXIIO” + a link to this page.
FAQ
Which chart do I need for a rooftop solar array?
Two of them cover the parts we have charted: the hanger bolt chart if your question is how the array is fixed to the roof, and the clamp size chart if it is which clamp holds the module. The bolt, nut and washer charts cover the parts that pair with them.
What decides which clamp size I need?
The module frame thickness you measure on the flange the clamp grips. The clamp is named after that thickness, the end clamp and the mid clamp share the same band, and the paired bolt stays M8 across the whole series.
Why is no torque value given for the clamp bolt?
Because a tightening value depends on the property class of the bolt, the friction condition of the joint and the module maker's requirement, and for these parts the property class is a drawing value. The method is published on the bolt torque chart and no maker's value is copied here.
Are the parts on this page standard parts?
Some are. The flange nut, the flat washer and the self-drilling screw are quoted against a standard number and the links go to those pages. The hanger bolt and the clamps are non-standard parts — there is no national standard for them, so they are made to drawing.
What if my part is not on this page?
Then it is a gap in our range rather than in your array: 4 of them are listed on this page with the reason. Send the drawing, the quantity and the project location and we will answer against it.
What documents should I ask for with a solar hardware batch?
The material test certificate for the heat, the reading of the standard it is issued to (EN 10204 3.1 or 3.2 depending on what you buy), and a receiving inspection against the drawing or the standard number before the parts go onto the roof.
Related References
Hanger bolts for roof mounts
Sizes, supply lengths, and what is left over for the roof build-up.
End and mid clamps by frame thickness
One band per module frame thickness, with the paired bolt, nut and washer.
Bolt torque chart
The K-factor method and the friction ranges behind any tightening value.
Bolt size chart
Width across flats, head height and thread length for hex bolts.
Values on this page and on the pages it links to are engineering reference values for selection and purchasing. Part dimensions, rail sections and installation values must be confirmed against the drawing, the batch inspection report and the project structural calculation before production or installation.