Solar panel tilt and orientation in Australia

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.

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

Comments

  1. 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

  2. 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

    1. 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!

  3. 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

    1. 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.

  4. 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

    1. 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.

  5. 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….

    1. 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!

  6. 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.

    1. 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!

  7. 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

    1. 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!

    1. 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.

  8. 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

  9. Hi, am asking for the formula that can be used to calculate angle of tilt in southern hemisphere by taking latitude into consideration

  10. We have a 3.5 kw system with 13 panels. Our next door neighbour has a smaller system and gets money back in the grid. We still pay a quarterly bill over $300. Do you know how we can check what is going wrong?.
    We paid over $10,000 for our system, get back 44 cents are in Sunny Queensland and don’t know why our bill is so different when both ours and our neighbours are faced the same direction, with no shade.
    Appreciate your reply

    1. Hi Jodie,

      Do you have an inverter that you can check? The first thing you’d want to know is whether the system is producing as much electricity as you’d expect it to – at least around 10kWh per day on average throughout the year.

  11. Hi, what is your view on having solar panels laid flat rather than tilted on a flat roof facing due north?

    1. Hi John,

      Flat or near flat tilt angle is optimal for locations in the tropics because the sun will sometimes be to the north of the solar array, sometimes to the south depending on the season. But even in non-tropical locations it may on occasion make sense to lay the panels flat as opposed to propping them up on tilt frames. Some examples might be if you have limited roof space or if you are on a tight budget – tilt frames do usually increase installation costs by about 10-12%. Interestingly, the loss in laying your solar panels flat if you live in Sydney (for example) is also about 11-12%. The impact increases as you go further away from the equator – e.g. Victoria and Tasmania would lose more than 11-12% so tilt frames might be worth the investment.

      One other thing to keep in mind with flat panels is that they do not self-clean as well as tilted panels – dust has a higher chance of accumulating and impeding electricity production. In contrast, the dust will generally wash off of tilted solar panels whenever it rains. We’ve seen figures showing the drop in performance due to dust accumulation as between 5-10%.

  12. I have a 6kw being 24 panels on a flat roof in Adeliade
    they sy in summer it should be left flat
    in winter bring them to 32 degrees
    now a question would it work better if one set of 12 panels were at 0 the other at 32 getting the best of both
    it a hard process to adjust 12 panels every time

    1. Hi Bob,

      Interesting question. I’m not sure about panels being laid flat for the summer in non-tropical regions, however–if you’re anywhere outside of the tropics, some degree of tilt is preferable, even in the summertime. This is because the sun is always between you and the equator in a non-tropic region, whereas the sun will ‘move’ to the south or north of you if you are in the tropics, depending on the season and your exact location.

      If anything, you would want to set up the 2 arrays on a summer-optimised tilt and a winter-optimised tilt. But as we note in the article above, homes tend to have more electricity demand during the summer months, when they run AC units. The case might be different if you have electric heating in your place, however.

      We recommend playing with some of the options on NREL’s PV Watts calculator tool, which you can access here. Let us know if you have any questions. (And make sure you put the azimuth at 0 degrees if you’re in Australia and north-facing! The default in the calculator is 180 degrees, which is for systems in the northern hemisphere.)

  13. Hi Chris
    We are looking at getting a 10kW Solar System installed.
    Our house runs N/S so we don’t have a north facing roof.
    I read articles on this website stating that “the West is the new North” so we were keen to get panel on our West facing roof.
    The Solar company we are talking to is recommending a 50/50 split between our West and East roofs.
    I have always heard that the East roof is that last place you want to install panels.
    We use most of our electricity on weekdays from 1500-2100 as my partner and I work and our kids are at Uni.
    We did enquire about getting a battery storage solution installed within 5 years once the price of these comes down. The Solar company advised that a W50/E50 split between W and E would be best for the battery backup, however I am concerned that this would not work the best for our current needs (and up to 5 years in to the future before we get the battery storage solution).
    I was hoping for a more W80/E20 or W70/E30 split
    Could you please give me your recommendation?
    Thanks in advance
    Hans

    1. Hi Hans,

      Congratulations! You seem to have educated yourself quite well on the topic of going solar and are asking some very smart and pertinent questions.

      If it comes down to a choice between East and West for solar panels, we do generally recommend that West is the better option, as afternoon is when homes tend to consume more electricity during the day, which makes the panels more useful. In your case, it definitely makes sense for you to have most of the panels West-facing since you know you’re home and therefore likely using more electricity from mid afternoon onwards.

      If you can, start looking in more detail at your electricity usage now to get a clearer idea of what amount you’re actually using–knowing this will inform you in selecting the best system size for your needs. (Also check out our articles on how to get the most out of your solar system.)

      A 50-50 split system may indeed generate (slightly) more power in total throughout the day, but the key to taking most advantage of a system these days is to consume as much of the electricity it generates as possible (‘self-consumption’), which means making sure you can take advantage of whatever power it generates while it is being generated. In your case, I think the W80/E20 split would probably be a better option than 50-50, because whatever excess solar power is generated in the morning (when you’re not using it) will simply be exported to the grid to earn you only around 8¢/kWh (actual rate depends on your state & electricity retailer), whereas consuming it yourself will save you 20-30¢/kWh on your power bill (again, depending on how much you pay for electricity).

      The US National Renewable Energy Laboratory has an excellent tool called PV Watts which is great to play around with to learn about how output from various system sizes & layouts will differ. Definitely check it out. The only slightly inconvenient thing is that in order to model output from a split system you’ll have to treat each side as a separate system and then add up the total output.

      Best of luck!

  14. hi we have 3.3 inverter 12 panels on a small tin roof house on the Gippsland lakes in Vic. The panels are North west facing and seem to miss the late afternoon sunlight – can another 3 – 4 panels be installed / added to the array with too much drama to catch the western sun?

    1. Hi Kevin,

      Whether you can add more panels will depend on your inverter and how many Maximum Power Point Tracker (MPPT) inputs it has. What is the total capacity of your solar panel array (different panel brands have different wattages)? You’d also need to make sure that your total panel capacity doesn’t exceed the maximum allowable capacity of the inverter.

  15. Hi Jarrah,

    I am having difficulty finding a standard for placements of solar panels on sheet metal roofing, namely;
    Solar panels extending past the roof line.
    We have 16 panels on a N/E facing roof with 4 of these panels extending past the roof hip. At the time of installation I was assured that this was ok, but now I’m not sure as another installer has told me differently. We have room on our roof the reposition the 4 panels in question.
    Is there an Australian Standard for this.

    Regards,

    Rob.

    1. Hi Rob,

      We’ve checked around to get some answers for you on this. The short of it is that the panels should really not be hanging off the roof at all. Most mounting frames and their standards suggest that panels are set back from the edge of the roof for access purposes and for wind rating.

      You should have been given a product manual (and if you weren’t you should be able to look it up online) and your installer should have verified the wind rating compliance of the solar modules.

      You could probably look into having the panels moved–as long as there isn’t some other reason that the installer decided to put them there (even though they really shouldn’t have). For example, was there shading on the area where you’re thinking about relocating the panels to?

      Best of luck!

  16. I have a strange roof. Several years ago we attempted to install solar panel on our roof but there was limited space on the north roof (maybe 3 panels). We thought 3 panels would be a waste of time so the installers advised us to install 9 panels on the west facing roof of the extension- a 1.6 Kw system. I didn’t realise at the time but the roof pitch is only around 10 degrees – a double whammy! Result – very poor solar.
    I wondered if you could advise the most cost effective thing to do now. I could
    1) install another 4 panels on the west roof of the main house with 45 degree pitch. (will the solar loss be any different to 10 degrees pitch)
    2) add a frame to tilt the current 9 panels to 30-35 degrees
    Thanks for any advice you can give me

    1. Hi Kim,

      Wow–tricky situation there. Let’s start by saying that unless you have microinverters or DC-DC power optimisers, it’s best not to split your solar arrays up too much. That being said, if you already have a centralised inverter, you’ll want to look first at whether or not it has the capacity to take on any additional panels, and if it does, whether or not that new string can be connected to its own input in the inverter–one separate from the input which your existing panels are plugged into.

      To answer your questions about whether a 10degree or 45 degree pitch would be better. I’ve consulted the PVWatts tool and it appears that the 45degree pitch is unequivocally better than 10. You can play around with options on this tool yourself (very useful) to get some idea about how to best proceed.

      Best of luck with your system!

  17. Hi,
    I am looking at getting a 3.0kw system in stalled on my house. The roof faces due East and has a pitch of approximately 12 degrees. The installer has advised that I will only lose about 6% efficiency compared to if the roof faced due North. Is this correct or is he under estimating the efficiency loss? From what I have read elsewhere the actual loss could be as high as 15%.

    1. Hi Rory,

      By my calculations, you’re looking at an efficiency loss of about 10% with that tilt and orientation compared to due north at optimum tilt. The estimation you’ve received is just shy of this, so probably a bit too optimistic.

      In any case, a 10% efficiency loss isn’t too bad, although it’s important to keep in mind that it’s never a bad idea to make more conservative guesses.

      If you’re still looking for a system, give us a ring on 1300 78 72 73 or fill out the form to the right of this page.

  18. Hi,
    Please, what are the physical features that identifies amorphous silicon solar panels and how can one measure the short circuit current of a solar panel?

    1. Hi Joel,

      Amorphous panels have a metallic blackish colour to them in most cases, but can also have a purplish-hue. Check out Q-Cells ‘Q.Smart’ panels for an example.

      As for testing open circuit voltage, for safety reasons I’d recommend consulting a professional electrician.

      Best of luck!

  19. Some of the threads relate to the issue of placing the panels in a way that maximises energy production when the household needs it -generally in the evening (e.g. tilting west). Isn’t that a somewhat pointless exercise as the reality is that most households use power when the sun isn’t even shining? So unless you can capture the power and store it for later use the system is rather pointless?

    Are there solar installers out there that will also install battery systems that release power at night? Otherwise it seems like a lot of money to produce power for an empty home (ie. when I am at work).

    1. Hi Frank,

      There are a few installers on our network who can offer installations with battery storage. However, due to high cost of current battery storage solutions this is not offered in the first instance. An appropriately sized solar PV system can help to offset some of the costs associated with day time energy use from white goods and other items that are plugged in constantly.

      Solar PV systems may not be for everyone and our Solar Brokers are here to talk customers through their options, helping them make a well informed decision of installer and have advised customers in the past that their current energy consumption patterns may mean that the ROI from a system may not make it a viable solution.

  20. Hello.
    My Dad just had a [non-Solar Choice installer] 3kw micro-inverter put on his shed two weeks ago.At its best all it puts out is 1.3kw & 9.5 kwa.It faces almost true West.About 10 to 20 deg towards the North.Should it put out more Watts than this.We live in Perth.

    1. Hi Chris,

      The output of your father solar PV system will depend on the panels and not the inverter size, the panels will be add up to 3kW at the most. The installer you mentioned is not on our network so we are unsure of their practices, however, some installers will recommend installing a larger than required inverter so you can ‘add-on’ later. If your father lives by himself he would potentially only need a 1.5kW – 2kW system, unless he is running air conditioning.

      If you find out how many panels he has and the wattage you can add them together and divide by 1000 to get the system size (e.g. 8 panels x 220 watts = 1,760, divided by 1000 = 1.7kW). If you think the system is under performing a good installer will come out and check the problem for you.

      Hope this helps.

  21. Hi, I have just had a 6kw system installed. Orientated at 309 degrees. (51 degrees west of north)
    10 panels are laid flat on the NW(309 degrees compass magnetic) side on a 2 degee roof pitch and 14 panels are laid flat on the SE (139 degrees Compass magnetic ) side on the 2 degee roof pitch. Should I tilt the panels? and if so what pitch? What would I gain by Tilting them?
    Regards John

    1. Hi John,

      In an ideal world panels would orientated due north with a tilt a few degrees below the line of latitude. Straying off the due north orientation isn’t a major issue but it will reduce your output by a few percent.

      If you have panels located on a number of different roof spaces at difference angles it may be worth while investing in a dual phase inverter or additional inverters to ensure that low performing strings do not lower the performance of the whole system.

      We hope this helps

  22. I have a solar system, 16 panels @190 watts per panel and 3kw inverter. 7 panels face north and 9 panels face west. According to the electrician they are wired even 8/8, which means 1 panel facing west is linked with 7 facing north. A neighbour has 15 panels @205 watts per panel all facing west, and a 2.5 inverter, his system produces on average 3 – 4 kws more than mine. There is no room for all the panels on my roof to face north, would it be better if they all faced west.