The sun rises from the East then to the Northern part of the sky, then sets back down on the West in the afternoon. See the diagram.If you have northern facing roof space without obstructions such as trees blocking the sun light, then it’s in your best interest to install the solar panels there.

  • The directional losses for NE or NW vary from around 3%-4%.
  • For a East or West facing roof, you can lose between 12% and 18%.
  • And if a sales rep or installer recommends that you install on the south.  Then I suggest you get a second opinion, unless you are in the Northern Hemishpere.
For those of you who do not have northern facing roof space, don’t stress.  It is not the end of the world, your efficiency losses will be minimal. You can install solar panels on the East and the West too. Just not the South!

Your solar installer or sales representative should be able to work out your exact directional losses.  Make sure that you ask for a plan or diagram indicating exactly where the panels will be installed.  And if they are good, you will also get a more accurate calculation for your directional loss, based on the exact pitch of the roof and the exact property location in Australia.

Next: When solar panels work