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On Thurs, 28 Aug 2014 the federal govt released long-awaited recommendations from the Renewable Energy Target (RET) Review that will either abolish the upfront federal subsidy for solar energy, or severely slash it, for systems up to 100kW.

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Your subsidy will then very likely be protected under transitional provisions recommended by the RET Review.

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Solar Panel Tilt and Orientation in Australia

Optimising the performance of your solar installation by using the correct tilt and orientation

by Jarrah Harburn on January 7, 2010

in Installation advice,Positioning solar PV panels

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, so panels need to be directed according to this positioning. 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. So in Australia, what angle and orientation are best?

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 website, 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 in short, the formula to remember for grid-connect systems is that the formula for optimum tilt angle is your latitude minus 10 degrees.

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 efficiency. Once again referring to the graph above, one can see that even North Easterly and North Westerly facing panels will be largely operating at around the 90% of their rated outputs. However, once angles start approaching East North East or West North West 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 getting back 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 would equal 88c worth of surplus energy in QLD and SA a day, $1.20 in surplus to Victorians, a minimum of $1.00 less in the ACT and $1.20 in NSW. A lot of energy that is not captured, and a lot of money that is wasted.

Read more: East vs West orientation for solar panels; which side is better?

Why 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. With a 1.5kW system and below you can get away with forgoing the frame, but anything larger and the fact is that 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, but expect to pay a minimum of $400-$500.

Top image via Your Home Technical Manual

Jarrah Harburn
Solar Broker
Solar Choice Pty Ltd

© 2010 Solar Choice Pty Ltd

Jarrah Harburn

Jarrah is the Director of Solar Choice’s UK subsidiary, Solar Selections. He has 3 years' experience in the UK solar industry following 2 years' experience with Solar Choice in Australia.

{ 196 comments… read them below or add one }

Chris September 7, 2012 at 5:39 pm

Hi,
We are in the process of changing the roof of our carport/shed at the end of our block. We thought it may be a good idea to get your advice as to how to construct the roof of the carport in a way that will be optimum for the installation of solar panels.
The roof of the house faces north eat but we want to install the panels on top of the car port instead.
Thanks in advance.
Chris

Reply

admin September 10, 2012 at 11:23 am

Hi Chris,

It’s hard to say without seeing the roof of your house and making sure nothing nearby is going to cause a shading issue.

As long as there’s no shading, it’s best to make sure the roof of the carport faces north. You can then use the formula in the above article (your latitude minus 10 degrees) to find the optimum tilt angle of the array.

If you’re looking for an installer, request a quote comparison to compare the offerings from solar installers in your area–some of them should be able to install on a carport roof.

Reply

Nigel October 2, 2012 at 11:57 pm

Hi Chris
I had solar panels installed at my home a year ago. I drew a diagram indicating where I wanted the panels for the best sun – as I have a mountain and trees behind the house. The installer disregarded my request, advising they were the experts on positioning. I’ve patiently waited, and now am sure that throughout the year, their positioning is wrong. How much would I be looking at to have them relocated as per my initial advice? Would this be worth my cost – as I have made minimal from them to date, and outlayed quite a bit.
Thanks

Reply

Solar Choice October 3, 2012 at 4:49 pm

Hi Nigel,

As your request is unusual we don’t have a set price as advised by our installers for relocating panels. If you feel that the performance is not what it should be relocation may be covered by the installers ‘Performance Warranty’ which last around 10 years, you may need to send them pictures or other evidence of the shading issue. I would recommend this as your first port of call as it will potentially cost you nothing and ensure your warranties remain intact.

Alternatively, you could get a second opinion from another installer, depending on their workload they may be able to relocate your panels and will be able to advise you of the cost. As a final option if the relocation involves no major work (the addition of cables etc) you may be able to employ a general trades person to do the job for you, in this instance I would look carefully at your Warranties to ensure that this does not make them invalid.

We hope this helps.

Reply

Jane December 20, 2012 at 7:45 pm

Hi, Chris:
We are about to have a solar system installed on our roof. The sales man came to inspect our house and said both North and West roof can be used. We prefered North but he recommended West. We are single story house and both our east and west side neighbours are double story. But we don’t think that would affect. May I ask for some advise from you?

Thanks heaps

Reply

Solar Choice January 3, 2013 at 2:34 pm

Hi Jane,

Without having a roof top view of your property or understanding your energy usage, it wouldn’t be possible to advise exactly why the installer has suggested West instead of North. A good installer should be willing to explain their advise to you, and you can check your contract as some installers have a clause that allows free relocation if the panels are not operating at their optimum level.

While placing your panels on a North facing roof is generally the best option, it may be that you have excessive shading on the Northern roof or your energy use behaviour means generating into the evening is a better option for you (west facing panels give you that little bit longer in the evening).

If you’re still not sure and haven’t installed as yet you can still complete our Solar Quote Comparison form. You’ll get 7 quotes from installers who operate in your local area, they may also be able to come and view your property and give you a second opinion.

We hope this helps.

Reply

jason gillam January 22, 2013 at 2:18 pm

hi guys, i’m building a carport/shed for a battery bank and a solar aray. I was wondering if you know what angle would be the best to direct it for a place called Kogan? (Search Google Maps and in the search bar copy and paste: -27.009202,150.686374) I’ll be building it facing north.. just trying to figure out a good all-year angle to pitch roof. We’ll only be running 80amps of solar panels to 800amps worth of battery in 12V. Thank you in advance.

Jason

Reply

Solar Choice January 22, 2013 at 5:25 pm

Hi Jason,

Sounds like an interesting project, generally speaking the optimum angle for your solar panels is the same as your line of latitude. In you case it would be around 27 degrees.

The exact installation set up is normally determined by our installer when on site, as they can take into account different factors that effect your property specifically.

Hope that helps

Reply

jason gillam January 23, 2013 at 12:34 am

thank you very much for your reply

Reply

margaret brennan January 26, 2013 at 4:08 pm

We wish to have solar panels installed on our house in Melb The house faces North (a single fronted Edwardian house with a roof tilted at a steep angle. We are unable to place them on the west side because of a chimney, so they have to go on the east side. A friend has told us that we should have tilted panels but the company we are dealing with say this is unnecessary and would look ridiculous Who is right?

Reply

Solar Choice January 29, 2013 at 8:55 am

Hi Margaret,

Without seeing your house we couldn’t confirm which would be the best option for you, it may be the steep slant on you roof is at the optimum angle for solar PV. If you want a second opinion you would be more than welcome to fill in our free Solar Quote Comparison, you’ll get quotes for up to 7 installers in your area so will be able to see if the quote you’ve received already is a good price. All of the installers on our network are Clean Energy Council Accredited, so you know you’re getting one of the good guys and not a cowboy, plus you’re allocated your own personal Solar Broker who can help you make an informed decision.

Hope that helps and we look forward to helping you soon.

Reply

Jason January 27, 2013 at 5:40 pm

I am v-interested in your comment to Jane above: ‘While placing your panels on a North facing roof is generally the best option, it may be that you have excessive shading on the Northern roof or your energy use behaviour means generating into the evening is a better option for you (west facing panels give you that little bit longer in the evening).’

We are thinking of splitting a 3kw system 50 North facing and 50 West facing. Our electricity supplier no longer offer a feed in tariff so we want to produce at the times we consume. If we have 1.5kw facing north we will probably produce at least as much as we use during the peak time of 11am-3pm. However, we estimate that orienting the remaining 1.5kw to face west will produce when we are more likely to need it more in the afternoon and evening time, ie. dinner and cooling/heating time, but only up to about 800w or maybe up to 1.3kw (taking account of the efficiency loss).

Can you advise if there is graph or curve that plots the hour by hour production of North facing panels together with West facing? Maybe we should opt for one or the other, but not a split system?

Reply

Solar Choice January 29, 2013 at 9:12 am

Hi Jason,

I’m afraid we don’t have any graphs that show the hour by hour production of North versus West facing panels, a good installer will be able to give you more information about what’s the best set up to meet your needs. Without seeing your roof it would be difficult to advise exactly what would be possible. We do have customers who have split their system across two roofs or others who have decided after speaking with ourselves and their installer that the single roof option is best for them.

To get you started you could complete our Solar Quote Comparison, not only will it give you instant quotes for up to three installers in your area but one of our solar brokers will be allocated to you and can access exactly what might be feasible. The form is located to the right hand side of our page and takes about a minute to fill in.

We look forward to helping you soon.

Reply

Gus Warren February 1, 2013 at 7:43 pm

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.

Reply

Solar Choice February 19, 2013 at 11:55 am

Hi Gus,

Your Solar PV system will only work as well as the worst performing panel. The west facing panels will be lowering the output of your north facing panels in the morning which could lead to the reduction you’re seeing, if your panels are older than your neighbour this will reduce their performance slightly but not to the level you’re seeing. This issue could be rectified quite easily, if you have a dual input inverter the 7 north facing panels could be wired separately from the 9 west facing panels.

If you don’t have a dual input inverter then moving all the panels to the west might be your best option. Some installer have a clause in their contract that states they will move panels for free if they’re not performing as well as they could be, so check your paper work.

Hope this helps

Reply

John February 4, 2013 at 8:38 am

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

Reply

Solar Choice February 19, 2013 at 12:49 pm

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

Reply

Chris Lomas February 4, 2013 at 12:57 pm

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.

Reply

Solar Choice February 19, 2013 at 11:29 am

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.

Reply

Frank February 7, 2013 at 1:52 pm

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).

Reply

Solar Choice February 19, 2013 at 2:22 pm

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.

Reply

Joel March 11, 2013 at 2:52 am

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?

Reply

Solar Choice March 12, 2013 at 3:54 am

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!

Reply

Rory April 8, 2013 at 6:54 am

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%.

Reply

Solar Choice June 26, 2013 at 12:10 pm

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.

Reply

Kim August 25, 2014 at 8:48 pm

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

Reply

Solar Choice Staff August 26, 2014 at 3:08 am

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!

Reply

Rob August 28, 2014 at 7:20 am

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.

Reply

Solar Choice Staff September 16, 2014 at 4:26 am

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!

Reply

kevin September 5, 2014 at 11:53 am

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?

Reply

Solar Choice Staff September 10, 2014 at 12:39 am

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.

Reply

Hans Evers September 10, 2014 at 10:25 am

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

Reply

Solar Choice Staff September 16, 2014 at 4:47 am

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!

Reply

Hans Evers October 10, 2014 at 3:58 pm

Thanks for your info.

Reply

bob October 10, 2014 at 5:00 pm

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

Reply

Solar Choice Staff October 14, 2014 at 6:08 am

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.)

Reply

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