What angle and orientation are best for solar panels in Australia?
Solar panels are installed differently based on their geographic locations throughout the world. The premise behind this is simple; the sun is in a different place in the sky, and solar panels should face it as squarely as is reasonably possible throughout the day.
The ideal situation is when the sun is hitting the panels at a perfectly perpendicular angle (90°). This maximizes the amount of energy striking the panels and being produced. The two factors that such an angle is controlled by are the orientation (North/South/East/West) and the angle of the panels from the surface of the earth.
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Tilting
The tilt involves primarily the angle that the panels are facing up into the sky. On a flat roof, the tilt is 0°, whereas if the angles were to be facing a wall, it would be 90°.
According to the Your Home Technical Manual the ideal tilt angle for a solar PV array depends on the building’s electrical load profile (i.e. when you use electricity during the day). The below description refers to tilt frames, but its recommendations are worth bearing in mind when considering installing a panel array on a roof without tilt frames.
As a rule of thumb, if the main loads are in winter months when solar availability is reduced, tilt angles should be more vertical (approximately equal to latitude plus 15°) to maximise exposure to the low winter sun. If major loads are cooling and refrigeration the tilt angle should be reduced (approximately latitude minus 10°) to maximise output during summer. For grid connect systems the summer optimum angle should be used to maximise annual output of the modules.
So if you have heavy summer AC loads in your home or business, the ideal would be to tilt the panels your latitude minus 10°. If your winter heating loads are supplied by electricity (as opposed to gas or wood), on the other hand, then tilting your panels back at latitude plus 15° would be better. If the loads are roughly equal in summer and winter, tilting the panels at latitude should be fine.
In effect, however, most grid-connected solar systems are likely to be installed at whatever angle the roof happens to be tilted at (unless the roof is completely flat, in which case the panels should be given a slight tilt). This is because the additional cost of tilt frames is not always justified by the additional solar system energy yields – it may be more cost-effective (space permitting) to simply add an additional solar panel or two.
Efficiency of solar systems at different tilt angles and orientations for Sydney.
Orientation
Australia, being in the southern hemisphere, experiences a sun that is predominantly coming at us from the north. There is of course deviance throughout the seasons, but ideally solar panels should be facing as close to true north as possible to reduce the impact that the winter seasons have on energy yields. Once again referring to the graph above, one can see that even northeasterly and northwesterly facing panels will be largely operating at around the 90% of their rated outputs. However, once angles start approaching east-northeast or west-northwest orientation, the numbers start reducing rapidly.
A directly east or west facing panel will never operate at better than 85% of its rated output. To put this in perspective, rather than generating the usual 4.5kWh average daily energy per 1kW of solar, the system will only produce 3.835kWh. For example, a 3kW system would lose a full 2kWh a day if it were facing more east or west than north. This translates into a reduction in the amount of savings that would other be possible.
Read more: East vs West orientation for solar panels; which side is better?
Read more: Can you install solar panels on a south-facing roof?
When tilt frames are a justifiable expense
So we can see that both of these factors are important in their own right. What the majority of houses and installations need to remember is that a combination of a not so great orientation and a poor tilt will add on to one another, making the consideration of both factors the only reasonable way forward. Tilt frames that counteract a sub-optimal tilt and orientation will cost you a little extra. How much will depend on how many panels make up the system, and how the installer sources and prices the labour and parts required.
The bottom line is that the bigger a system is, the more justifiable that expense becomes – especially on a flat roof. In the ideal scenario, the cost of a tilt frame will be paid for with the increased efficiency and day-to-day output of your system. Shopping around to get a number of quotes is the best way to find a reasonable price for the frames.
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© 2017 Solar Choice Pty Ltd
Top image via Your Home Technical Manual
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Hi,
we want to install solar panels on a north/south facing roof in Blantyre/Malawi. Blantyre is at 15 degrees south, almost at the same latitude than Darwin in Australia.
We are considering to install solar panels on the north and south facing side of the roof. The roof is tilted at about 15 degrees. There is no shading from either side. I presume that there is no great difference in solar radiation. Is that right?
Could you please let us know the difference in energy production between the north and south facing sides of the roof. Is there a formula one can use for the calculation?
Thank you
Hi Volker,
Thanks for the comment. You can check out our article about south-facing solar panels here, but in a nutshell, if you’re in the tropics and your roof pitch isn’t extreme (yours isn’t) then it shouldn’t be a big problem.
If you’re looking for an calculator that will help you estimate the output from the system array you’ve described, try out the PVWatts calculator.
Hi i have a 3kw system with 11panels facing west tilted can i tilt the two on the southern end side up to face north i cant tilt any of the other one they will shade each other or do they have to be all be tilted the same Thanks
Hi Allan,
Unless you’ve got microinverters, I definitely wouldn’t recommend tilting only some of the panels. If you’ve got a single, central inverter (as most systems do), then you could run into issues with system output, as best practice is for all panels in a ‘string’ to be at the same angle & orientation.
Hope this helps!
Sorry the later half of my comment is a bit confusing. What She said to me over the phone is that a configuration of 9 north facing panels and 9 west facing panel produces more output during the day than 14 north facing panels 4 west facing panels. Mentioned that only 4 panels facing west would not produce enough startup power for the inverter thus making the 4 panels useless. Unit on a cloudy day produces 13-15 kw and on sunny non cloudy day 19-21 kw.
Thanks dev
Hi Dev,
Generally speaking, it’s better to have all of your panels facing north, although there is sometimes an argument for having west-facing panels – although this is generally the preferred fall-back in the case that there is no north-facing roof space available.
You can get some estimates on expected output for your system under both scenarios using PVWatts, a calculator tool from the USA’s National Renewable Energy Laboratory (NREL) which also works for Australia. You’ll have to model the scenarios in chunks because it doesn’t allow for multi-direction solar arrays.
Hope this helps.
Hi, I just got a 4.77kw with 18x265w panels install in Sydney. It was a cloudy day and I could not see the angle of the sun. I have no solar experience. The installer told me that he wanted 9 out of the 18 panels to be installed west ( different to what they had. In the diagram they had 12 panels facing north) facing to which I said That I would prefer to have as much facing north as possible as there were space to put another 5-6 panels north facing on the roof but on a lower level to the 9 panels facing north(doulble story level). Lower level panels would have one or two panels shaded until 10.30am but would have full sun after that He told me that west facing panel are better especially during summer months. Not knowing anything about solar I said you are the expert do what you think is good. After reading your article regarding having panels facing north I rang them up and complained. I was informed by the manager is that having 9 panels west facing is better than just having 3 or 4 facing west would not have sufficient startup power for the west facing panel and what they did was right. I am confused. Are they correct. Does having 9 panels facing west make much difference to the output?
Thank You
Your link to the “Your Home Technical Manual website” is broken but the LDF can also be found at http://www.livingsmartqld.com.au/modules/energy/PDFs/PhotovoltaicSystems.pdf
You also quote their text, then immediately summarise it with the tilt angles reversed. I’m surprised no-one else has noticed.
Hi Moz,
Quite frankly, we’re quite surprised as well – a glaring, egregious typo if there ever was one. We’ve just corrected it and also added in the PDF link – thanks for pointing it out.
hi. I have a marine buoy I’m kitting out with a 12V system for a research experiment. the buoy will swing, pitch and spin, so, 2-3 sides will always be shaded. I was going to have a solar panel on all 4 sides. What would be the best wiring to maximise charge? 1 MPPT and just a blocking diode on ech panel? Or 4 MPPTs? Then what? Thanks heaps….
Hi Charlie,
We deal mainly in residential and commercial rooftop solar PV so can’t really answer your question with confidence (although other readers here are welcome to give it a go).
My quick thoughts would be that if you have only 1 MPPT, it would be tricky to have 4 panels all facing in different directions and still get the output you desire. Your idea for bypass diodes might not be a bad one, but we’d recommend getting advice from an electrician rather than us.
Best of luck!
Q:
What do you do with solar pane orientation if it is in location close to the equator where the sun location will be 6 months south and 6 months north.
Please advice.
Hi Kharbat,
In the tropics it makes sense to lay the panels close to flat, although at least a slight angle (5-10%) should be maintained so that the panels can still ‘self-clean’ in the rain.
Hope this helps!
Hi,
Can you provide a link to a website where you can put in your address to get the roof image in the winter in NSW to check best positions for installing new solar panels? Thanks. Sharon
Hi Sharon,
Nearmap is a great service for that type of thing, but unfortunately it’s a very expensive service. However, you can sign up for a 30 day free trial if you only need to use it once. Google maps may help you to do the same thing, but it’s not as up to date as Nearmap (which may not be a problem in your case).
You can also try out PVWatts, which is great for estimating solar output for a given home – but it doesn’t take into account shading from nearby objects.
Hope this helps!
Can I installed array panels facing north?
Hi Sabet.
Generally speaking, if you’re in the southern hemisphere, a north is the preferred direction for a stationary solar array. All other factors being equal, a north-facing array will produce more energy than a west or east-facing array. If you’re in the northern hemisphere, south is the preferred orientation.
Hi,
We had the Solar panels installed from 2 different companies. 1.5KW from each company totaling 3KW.
Reg. the Inverter installed by the Company#1; it stops working on and off; it works for 2-5 minutes and then it goes into Alert or Alarm mode, producing zero power for the next 2-5 minutes. The Cycle gets repeated throughout the day. There was very low power generation from this particular Inverter. When we complained to the Company#1, they said the problem was with the Grid not their Inverter. We reported to Integral and they said there is nothing wrong with the grid.
The Inverter from Company#2 is working fine. When we showed that to the Company#1 the, they simply ignore it.
Can I just swap the Inverter myself. I am loosing a huge money as the unit price I am paid was 60cents.
Please advise.
thanks
We can’t advise changing out the inverter yourself unless you’re an accredited solar installer, but we do know of a company that specialises in this sort of service. Their name is Solar Safe and you can find out more info about them here.
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