Home Sizing the System The Structure The PV panels Field Wiring Tilt Angle

The PV panels


Each bay of the structure accommodates four PV panels mounted on a pair of struts that have been clamped to the rolling axle.  For the Kyocera KC-120 panels, the optimum strut spacing is 55-3/8" measured between outside edges.  The axle clamps are left loose to permit fine adjustment and alignment as the panels are being attached.


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PV mount (26517 bytes)

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The mounting hardware is installed on each panel before placement on the struts.  The 1/4"-20 x 1" bolt and the washers are 316 stainless steel.  The channel nut and square platform washer are galvanized steel.  Using stainless components in contact with the aluminum PV panel frame resolves concerns about dissimilar metal corrosion, although this is not a likely problem in our dry  climate.


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With the struts clamped horizontal, the panels are set in their approximate positions. The channel nuts drop into the channel and the assembly can be moved and aligned in the track.

The best alignment procedure I found was to make several passes tightening the bolts finger tight while wiggling the channels to index the channel nuts. I used some extra square platform washers as temporary spacers to maintain a small space between panels. After several iterations, the entire frame becomes magically square and aligned. Then the bolts can be tightened to the final torque.

Next is a visual warp check is made with corrections as required. Then the two loose axle clamps are tightened. 

With the frame still held horizontal, a length of 1-1/2" pipe is clamped to the south end. This pipe will provide an attachment for the elevation adjustment braces.


1133.jpg (110943 bytes) The frame is rotated into position for attaching the elevation braces. A 1-1/2" fender washer is sandwiched between the pipe strap and brace at the lower joint. This allows the joint to rotate freely.


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Finally, with assistance from a calibrated 2 x 4, the completed frame is fastened at the desired angle. Future adjustments are made by loosening the upper pipe straps, moving the frame to rest on a calibrated 2 x 4 for the desired angle, and retightening the straps.


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Two styles of connection hardware are available; a lightweight "pipe clamp" and a heavy duty "pipe strap". The pipe clamp is probably adequate for this job and is inexpensive (130 lbs axial force and about $0.50). The heavy duty pipe strap, my preference, provides a much stronger joint and costs a lot more (about 800 lbs axial force and about $2.25 with the additional hardware needed).

For the 2" pipe connections that hold the frame struts to the rolling axle, I recommend the stronger pipe strap.

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Pipe Clamp
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Pipe Strap