Improve the fixture of HIACE VAN solar panel

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Very difficult to detach the panel

The solar panel was mounted on the roof with roof carrier.

The panel is fixed onto the carrier by C-shaped metal parts and hexagon head bolts and nuts.

I hope my poor drawing below may help you.

Fixture of solar panel

The solar panel is fixed on the cross member of roof carrier with C shaped metal parts and M6 hexagon bolts and nuts.

improve the fixture of solar panel
C shaped metal parts

You’ll see the below image if you see the direction of arrow B shown in above drawing.

(The bolts and nuts are already replaced by butterfly nuts and bolts.)

improve the fixture of solar panel
Outside view of fixture

 What is the problem ?

It’s not easy to grasp the structure by seeing the photo above, but the solar panel is reinforced with channel steel. C-shaped metal parts are fixed on the channel steel with hexagon bolts and nuts.

The section painted in red is channel steel, and hexagon nuts are placed inside of the channel steel. So if you want to detach the solar panel, you must clamp the nuts through the gap under the panel (1) or from the opposite side of the panel through the inside of the structure (2), and both are not easy task.

Otherwise, the nuts corotate with the bolts and you never be able to loosen the screws.

To clamp the nuts, put a ring wrench into inside of channel steel, and insert the nut into the wrench by touch. But it’s really hard to keep the wrench and the nut together, and loosen the screw. Besides, ladder is necessary to do so, so you cannot do anything if you find the screws loosen when you are away from home.

It’s surely very dangerous.

Improve the fixture to ease the task

improve the fixture of solar panel
I hatched 2 plans

I hatched 2 plans.


Replace hexagon nuts with square nuts, then square nuts are blocked by channel steel and you can loosen and tighten the screws without clamping the nuts.


Replace hexagon nuts and bolts with butterfly nuts and bolts, and you can easily clamp the nut to loosen the screws.

Result of investigation

I tried to find suitable square nuts, but I couldn’t find the one large enough to be blocked by channel steel.

improve the fixture of solar panel
square nut

So I must stick to plan (2).

I ordered butterfly bolts and nuts to Monotaro , popular EC site selling industrial tools and materials.

Steel ones are much cheaper, but I don’t want to take a risk letting nuts and bolts get rusty to be broken, so I purchased stainless ones.

improve the fixture of solar panel
butterfly bolt
improve the fixture of solar panel
butterfly nut

Replace all the nuts and bolts

It took more than 4 hours to replace all the nuts and bolts, because it’s difficult to loosen the hexagon nuts and bolts as mentioned above. But after replacement, it is very easy to stop corotation with bare hand.

Thank you for reading my article.


The original article was written and published on May/24/2018.

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