Solar Panel Alignment (Revised 2015)

Author: Brian August 5, 2015

The suns position in the sky varies throughout the year and over each day.

The ideal situation is when the sun is hitting the panels closest to a perfectly perpendicular angle (90°).

So in Australia, what angle and orientation are best?……….. Well when mounting solar panels there are two elements of the alignment that affect the final efficiency of the panels.

Orientation – the compass direction the panel faces

Ideally in the southern Hemisphere solar panels should be facing as close to true North as possible to reduce the impact that the Winter seasons have on efficiency. Once the angle is above 30 degrees from North the efficiency really starts to drop away.

Tilt – the angle from the horizontal

The tilt is the angle that the panels are facing up into the sky. On a flat roof, the tilt is 0°, whereas if the panels were on a wall, it would be 90°.

The best tilt angle for more even efficiency throughout the year is generally the same angle as the degree of latitude of the site. Best for if your only power supply is solar.

Flatter tilt angles increase the power generated during summer, but reduce the winter power generation. If you have a system connected to the grid then you can go 15 degrees flatter than the degree of latitude without losing annual efficiency. (It can even help if your roof doesn’t face directly North)

Alignment Efficiency Table

The table below provides an indication of the approximate solar panel efficiency levels for Melbourne for various alignments.

Orientation	Tilt
	15 degrees flatter	Angle of latitude	15 degrees steeper
North	100	100	94
30 from North	98	96	90
60 from North	93	89	82
90 from North	86	79	71

The following site will carry out calculations for sites around the world:

http://pvwatts.nrel.gov/version_5.php

2015 Update

I first wrote this post in 2012 but since then a fair bit has changed.

Off Grid

If you are going to be ‘Off Grid’ its still best to have panels at the optimum alignment.

Grid Connected

If you are still connected to the grid the ‘Feed In Tariffs’ are now that low that there are real advantage in a more westerly alignment.

This means you are generating more power in the late afternoon-evening when you are most likely to be home and using it.

As the cost of panels has gone down it can also be more economical to have a couple of extra panels; rather than pay for angled mounting brackets.