A fixed panel mount is a rigid frame of angle iron, lumber or bamboo that holds the panel at a set tilt, facing true south in the northern hemisphere, with the high edge raised by the panel length times the sine of the tilt angle. For a 0.794 m panel at 45 degrees that is 0.561 m. Set the tilt by trigonometry, check the aim with the shadow of a pin, and brace the frame against wind.
Part of Solar Panel Construction
Building a fixed-tilt frame for a solar panel and setting its angle and direction.
The Frame Holds Tilt And Direction Against Wind
The carrier says to build a frame from angle iron, lumber or bamboo and set the tilt angle equal to latitude for year-round average performance, facing true south in the northern hemisphere and true north in the southern. The frame has three jobs: set the angle accurately, keep the panel from moving in wind, and leave the back of the panel open to air so it does not overheat (general knowledge, not from the other articles: a hotter cell gives a lower voltage).
What You Need
- Frame material — angle iron, sawn lumber or bamboo, with fasteners
- Rust or rot protection — paint or preservative; bare iron rusts and untreated wood rots
- Footings or ground anchors — stakes, stones or concrete to hold against wind
- A protractor or a measured template, a plumb line and a level
- A pin and a shadow board — to check the aim
- A true-south line — Finding True South
Method: Build And Aim
Step 1: Compute the geometry (worked example below) for your latitude.
Step 2: Cut and join the frame: two front legs, two taller back legs, and cross-members. Brace diagonally, because a frame that racks lets the panel move.
Step 3: Place the frame on the true-south line, with the panel’s low edge toward the equator and its high edge toward the pole.
Step 4: Mount the panel on the frame with bolts or straps that allow no slop, leaving a gap behind it for air.
Step 5: Check the aim. Fix a thin pin square to the panel face. At solar noon the shadow of the pin should be at its shortest and lie along the true north-south line. Near an equinox, with the tilt equal to latitude, the pin casts almost no shadow because the panel then faces the noon sun squarely (the shadow-pin technique used in Manual Sun Tracking).
Step 6: Secure the frame to the ground and re-check after the first storm.
Worked Example: Leg Heights For A 0.794 m Panel
The panel length from the encapsulation example is 0.794 m (Panel Encapsulation and Framing), laid along the slope. For tilt θ the high edge is above the low edge by 0.794 × sin θ, and the horizontal run is 0.794 × cos θ.
| Tilt | Rise | Run |
|---|---|---|
| 30° | 0.794 × 0.500 = 0.397 m | 0.794 × 0.866 = 0.688 m |
| 45° | 0.794 × 0.707 = 0.561 m | 0.794 × 0.707 = 0.561 m |
| 60° | 0.794 × 0.866 = 0.688 m | 0.794 × 0.500 = 0.397 m |
If the front legs stand 0.30 m high (a choice that keeps the panel clear of ground plants and snow; the height is assumed), the back legs for a 45° tilt stand 0.30 + 0.561 = 0.86 m. The two side rails slope between them. As a check, the diagonal across the rise and run should equal the panel length: √(0.561² + 0.561²) = 0.793 m. For a tilt equal to latitude, use the latitude in place of θ.
Common Mistakes
- A flimsy frame — wind racks it and moves the aim
- Bare iron or untreated wood — it rusts or rots within years
- A frame aligned to a compass south — magnetic and true south differ by 5–20° or more
- Panel flat against the frame with no air gap — it overheats and the voltage falls
- Ignoring shade from the frame’s own back legs — in a row of panels, space the rows so the front row does not shade the next
Safety
A panel is live, heavy and acts as a sail
The panel produces voltage whenever light reaches it, so cover it or leave it disconnected while mounting, and treat it as live regardless; three 18 V panels in series make 54 V and six make 108 V. A glass panel presents a large area to the wind and can pull a poorly anchored frame over, with glass that cuts. Use two people, wear gloves and eye protection, and anchor the frame firmly before fitting the panel.
What’s Next
- Learn next: Seasonal Angle Adjustment — letting the tilt change with the seasons
- Combine with: Mounting and Orientation — the rules for where to put it