Which roof face should I put my solar panels on in North QLD?

The direction you choose to have your solar panels on can definitely have an impact on the results you get.

There are a number of factors to consider

  •  What time of day do you use the most power?
  •  Do you mind if your solar panels face out to the street?
  • Are there any shading issues in particular directions?
  • How many solar panels can you fit on each face?
  • How far north or south are you?

Each of these can and should have an impact on your decision.  So let’s go through the impact of each.

What time do you use your power?

A few years ago when feed in tariffs were very high, the time of day you used power was not really that important.  The idea was to feed as much power into the grid as possible.

Now in Queensland 2018 it is the total opposite. Maximising your self use is the key to getting the most out of your solar PV system.

So ask yourself,  do you tend to use power in the afternoons more than the morning? Only at night? An even spread throughout the day?

  • If you tend to use more power in the afternoon, often west may give you the most benefit as the system will shut down late in the day.
  • Perhaps you use it only at night then feeding as much into the grid is the best way, north may give you the best benefit.
  • Maybe you use an even spread through out the day, east and west can often give you the best benefit.

Are the aesthetics important to you?

  • Remember your solar panels will be there for a very long time. Many people do not like the look of them all over the front of the house facing the street.
  • It may also effect the saleability of your home in the future.
  • Of course if you only care about power production then it is not a concern.

Personally I love the look of my whole roof covered in clean green renewable sources. However  but it is not uncommon for people to take this into consideration and install in a different location, for this reason.

Are there any shading issues in particular directions?

The number one killer of performance in solar pv systems is shade. While there are products that can help like optimizers and micro inverters.  The cold hard facts are solar need sun to work.

Often the performance benefits of micro inverters and optimizers are wildly overstated by  sales companies. They  know they can get better profits from selling a product with more “selling points”  rather than,  the actual benefits being relevant to your result over time.

For example, if you have a  trees overhanging your north roof shading it for 4-6 hour a day but a clear south roof.  Particularly in North Queensland, Cairns, Townsville, Mackay,  panels on the south roof where there is clear sun will give you a much better net result, than placing them in the shade using microinverters.

At the end of the day avoid shade as much as possible. If it is absolutely impossible to avoid shade, then it using enphase micro inverters or tigo optimizers may be the only workable solution.

Above – A classic example of a poorly designed solar panel system shaded by obstructions.

How many solar panels can you fit on each face?

Solar panels operate in what is know as “Strings” . Depending on the inverter they all have different “operating voltages”  putting to many or too little in a string can effect performance considerably.

As an example, if your inverter startup voltage of 150 volts and you only have 5 panels in a particular direction. They may start to operate very late in the day and stop working much earlier than they should as they do not make it to the required voltages for the inverter to make power. Higher quality inverters often have “wider operating voltages” than there cheaper counterparts.

As a very general rule more series panels to a string (within the limits of the inverter operation capacity)  brings the voltage higher meaning it will start earlier and finish later in the day.

How far north or south are you?

In Cairns, Townsville and Mackay Queensland lower pitch south facing solar  panels can often outperform east or west that have a high  roof pitch.  How ever if you are in Melbourne, a south facing roof can have quite dramatic effects.  So its important to understand your location makes a very big difference to the result. Any reputable solar supplier will provide with an accurate performance estimate using good quality software that allows for orientation and location.  If they do not do this, then its a good bet you are not dealing with a quality supplier.

To conclude, solar is not a one size fits all solution.  The design can have long lasting results so it is important to deal with a company who actually understands the performance charactertics of your area.

Cheers.

Leon

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