Fixed or adjustable panel mounts

Is it worth changing the tilt by season?

It can be. The sun's path shifts through the year, so a panel tilted for one season is a little off in the other. The tilt angle can be varied by season, and some systems do adjust it based on the time of year.¹²

The logic is the same as on the page about choosing a tilt angle. Steeper angles suit big winter loads, and lower angles use a greater fraction of the summer light.³ A seasonal mount lets you do both, instead of splitting the difference.

What the sources don't give is a percentage for the extra energy. So there's no honest figure on this page. If you want one, an installer can model it for your address.

When is a fixed mount fine?

Often. Rooftop panels for homes and small businesses are usually fixed, and they're often flush-mounted on a pitched roof that faces the right way.⁴ The reasons are practical: a fixed mount is simple to make and cheaper to install and maintain.⁴

Two more points help a fixed panel's case.

• It's forgiving. A flat panel that's 25° out of line with the sun loses less than 10% of the direct light.⁴
• It's easier to make sturdy. With a fixed mount, it's easier and cheaper to provide a sturdy mount against wind.⁴

A fixed mount also suits you if you can't get to the panels easily, or if you'd rather not be on a ladder twice a year.

What about wind?

A tilting frame is more exposed than a panel lying flush against the roof. Every mount other than a fixed, flush-mounted panel has to be designed carefully for wind loading, because there's more of it to catch.⁴

That matters when you add a hinge or a long prop. Use a frame made for the job and follow the maker's instructions for your model. If you're building on a roof or a tall pole, ask an installer or an engineer to confirm the design suits the wind where you live.

Should I just fit a tracker?

Trackers turn the panel to follow the sun. Against a fixed mount, a single-axis type adds approximately 30% to the year's output.⁴

That gain comes with a cost. Trackers add mechanical complexity and a greater need for maintenance.² They also add cost, which is why fixed mounts are more common.¹ Whether that trade is worth it for a small off-grid array is a judgement call.

How do I decide?

Work through three questions.

1. When do I use the most power? A fixed tilt for a stand-alone system should be set for the part of the year when demand peaks.¹
2. Can I reach the panels safely? If the answer is no, a seasonal mount that nobody adjusts is worse than a fixed one set sensibly.
3. Will I really do it? An adjustable frame only helps if someone changes it at the right time.

Is any of this electrical work?

Moving a panel on its frame is a mounting job, but cables are often involved. In Australia, anything that touches fixed mains wiring belongs to a licensed electrician, not a DIYer. A seasonal change that pulls on the cabling should wait until the battery is isolated. Check the manual for your model. Hand it to a licensed electrician if you can't tell what's safe.