Clamps and Bolts: A Practical Guide to Dimensions

If you need to find the right screws for your clamp, you’ve come to the right place! Below is a useful table to help you select the correct screws depending on the size of your clamp. The size of the clamp depends on the thickness of the solar panel, which is why choosing the screws carefully is so important. Take a look at the table below to ensure you select the correct components.

added: 09-04-2023

Clamps and bolts: A practical guide to dimensions

If you need to find the right screws for your clamp, you have come to the right place! Below you will find a handy table to help you choose the correct screws based on your clamp size. The clamp size depends on the thickness of the solar panel frame, so selecting the screws carefully is essential.

How do clamps and screws work together?

Clamps secure the panel to the mounting profile. End clamps hold the outer edge of the first and last panel in a row, while middle clamps hold two adjacent panels at once. The screw length depends on the clamp height and on the base it is screwed into – a T-slot profile, a hex-bolt profile or a trapezoidal bridge.

All screws in the table are socket head cap screws DIN 912 M8 made of A2 stainless steel.

Screw sizes for end and middle clamps

Find your clamp in the first column and read the screw size for the profile or bridge you use:

Symbol	Name	T profile	Hex profile	Trapezoid bridge (for slot)	Trapezoid bridge (for hex screw)
PV-03-01	End clamp H30 aluminum 6060 hole M8	M8x20	M8x20	M8x20	M8x20
PV-03-02	End clamp H30 aluminum 6060 hole M8 anodized	M8x20	M8x20	M8x20	M8x20
PV-03-03	End clamp H32 aluminum 6060 hole M8	M8x20	M8x25	M8x20	M8x25
PV-03-04	End clamp H32 aluminum 6060 hole M8 anodized	M8x20	M8x25	M8x20	M8x25
PV-03-05	End clamp H35 aluminum 6060 hole M8	M8x25	M8x30	M8x25	M8x30
PV-03-06	End clamp H35 aluminum 6060 hole M8 anodized	M8x25	M8x30	M8x25	M8x30
PV-03-09	End clamp H40 aluminum 6060 hole M8	M8x30	M8x35	M8x30	M8x35
PV-03-10	End clamp H40 aluminum 6060 hole M8 anodized	M8x30	M8x35	M8x30	M8x35
PV-03-20	End clamp - adjustable by sliding grooves M8 30-50mm	M8x16	M8x16	M8x16	M8x16
PV-03-21	End clamp - adjustable by sliding grooves M8 30-50mm - anodized	M8x16	M8x16	M8x16	M8x16
PV-03-22	End clamp 30mm with screw and insert	M8x20	M8x25	M8x20	M8x25
PV-03-23	End clamp 30mm with screw and insert - black painted	M8x20	M8x25	M8x20	M8x25
PV-03-24	End clamp 35mm with screw and insert	M8x25	M8x30	M8x25	M8x30
PV-03-25	End clamp 35mm with screw and insert - black painted	M8x25	M8x30	M8x25	M8x30
PV-04-01	Middle clamp H24 aluminum 6060 hole M8	Same as at the end
PV-04-02	Middle clamp H24 aluminum 6060 hole M8 anodized	Same as at the end
PV-04-03	Middle clamp H8 aluminum 6060 hole M8	Same as at the end + 15 mm
PV-04-04	Middle clamp H8 aluminum 6060 hole M8 anodized	Same as at the end + 15 mm

Middle clamps H24 use the same screws as end clamps for the same panel. For the low-profile middle clamps H8, add 15 mm to the screw length used for the end clamp.

Clamps supplied with a screw

Some clamps come with a screw and insert in the set, so you do not need to select screws separately:

Center clamp H25 L50 with M8x20 screw and insert – for 30 mm panels.
Center clamp H25 L50 with M8x25 screw and insert – for 35 mm panels.
KLIK clamps (type 2) with a mounting clip and A2 bolt: End clamp H30 KLIK silver, Side clamp H30 KLIK black (for panels with a 30 mm frame, compatible with hex-bolt profiles, tightening torque max 20 Nm), Middle clamp KLIK silver and Middle clamp KLIK black.

Black clamps for black panels

For all-black modules you can choose clamps with a black finish – anodised, painted or powder-coated – for example the End clamp H30 painted, End clamp H32 painted or End clamp H40 powder-coated black for 40 mm frames.

Best practice: if you use anodised (including black) clamps, remember about grounding – use grounding washers or clamps with a grounding pin. Read more in our article Grounding in a nutshell.

Summary

Choose the clamp height to match the thickness of the panel frame.
Read the screw length from the table for your profile or trapezoidal bridge.
Low-profile middle clamps H8 need a screw 15 mm longer than the end clamp.
Clamps with a screw and insert, and KLIK clamps, come with the screw in the set.
For anodised clamps, ensure grounding with washers or clamps with a grounding pin.
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