Why have solar arrays always faced North?

Why have solar arrays always faced North?

On the surface, this appears to be a dumb question.  We have typically face our solar arrays towards the equator (that's North for us Southern-Hesipherians) since day dot.  But why, and is there a more suitable orientation for your personalised usage curve?

Solar PV officially began back in 1839 when the 'photovoltaic effect' was first discovered. Though it was 2001 in Australia when the federal gov introduced the first Renewable Energy Target. It was this critical point when we first saw the sky-high feed-in-tariff (FiT) of $0.60kW/hr, and solar PV gained traction. Check out this brief history of solar PV in Australia.

Q. So why North hey?
A. To maximise solar energy generation.

Yes, to maximuse the total amnount of energy that is generated from your solar array throughout the day.  Because after all, we were trying to feed-in as much energy as possible for the $$$.  But times have changed, and the FiT is significantly lower than it was.  For Victoria it is currently around $0.125 kW/hr (about half of what you pay to use energy from the grid). With this in mind, I have this question?

Which way should they face according to how much and when I use energy?

The basics of orientation...

  • North - Generation is high in the middle of the day and medium in the morning and afternoon, producing a typical bell curve shape.  Produces the highest energy yield over a given day.
  • East - Morning, you will get a spike and trail off as the day goes on.
  • West - You'll most likely starting generating from about noon till sunset.
  • South - Least ideal overall as they're tiling away from the suns arc but possible.

The Clean Energy Council offer a table of tilt angles and orientation angles for each capital city in Australia with an efficiency decrease from the ideal.  If you're not into heavy datasets, here is a summary chart for a typical roof tilt within Australia (about 20 degrees).  So this chart says, if I orient my solar array to the North, East, South or West, how much overall energy do I lose compared to an ideal tilt and orientation.  The ideal is usually facing towards the equator at an tilt angle equal to the latitude of your location.

But... What I'm questioning here is... when do you use energy throughout the day, and how much every hour?  Do you have a morning spike, then it chills during the day till you get home?  Or are you at home throughout the day and your energy consumption is pretty flat until the evening?  This is extremely important for many reasons; economic return, grid stability, your bills.

At this point, I'm going to leave you hanging right here.  Here at SolarBI we're working on optimising this for you.  We're building a model so you can pump in your energy consumption data, where you live, and we'll give you a customised report of where your best bang-for-buck is for your solar PV.  Until then, please ask your solar installer the question, which orientation is best for the way I use energy?

Get in touch with us if you'd like to chat more. We love feedback and ideas.

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