Choosing a tilt angle for your latitude

What tilt suits a fixed panel?

Start with your latitude. That's how far you are from the equator, measured in degrees, and any map app will tell you. For a fixed panel, the most power over a whole year comes when the tilt angle equals the latitude of the place.¹

It's a common rule in practice too. Tilt angles equal to an installation's latitude are common.² The tilt is measured from the horizontal.³

In Australia the panel tilts toward the north, because that's the direction the module faces in the Southern Hemisphere.¹ Finding true north is covered in the guide to facing north.

Why does the right tilt change between summer and winter?

Because the sun's path moves. Over a year the sun swings through 46° north and south.⁴ In a Southern Hemisphere summer, the sun peaks only slightly north of overhead.⁵ In winter it rises in the north-east and reaches just a low angle in the north.⁵

A panel tilted for the low winter sun stands steeper. One tilted for the high summer sun lies flatter. Steeper angles suit big winter loads, while lower angles use a greater share of the light in summer.¹

So is the latitude rule always right?

No. It gives the most energy across the full year, but that's not always what an off-grid household needs.

For a stand-alone system, a fixed tilt should be set to give good output during the time of year when demand for power peaks. That angle isn't necessarily the same as the one that gives the most energy over a year.³

Here's what that means in practice.

Think about the time of year when your power use is highest. That's the season to tilt for.

What if I can change the tilt twice a year?

Some systems do. The tilt angle can be varied for the season, and some systems adjust it based on the time of year.³²

The sources here don't say how much extra energy that gives, so these notes don't promise a figure. The next question is about effort and risk instead of energy. Fixed or adjustable mounts goes through it.

How do I measure the angle once it's up?

A builder's angle finder works, and so does a spirit-level phone app laid along the panel's frame. Set the panel, then check it again once the bolts are tight.

Do I need an electrician?

Setting a tilt is a mounting job. Wiring panels to a battery or inverter isn't a beginner's DIY task. In Australia, fixed mains wiring and grid connection are licensed electrical work. Should an angle change disturb any cable at the battery or inverter end, isolate the battery before you start. Follow the maker's manual for your model. Unsure? Call a licensed electrician.