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Have you noticed that most solar panels installed on Australian roofs are installed vertically?

Longitudinal is more popular because solar panels are cheaper and faster to install in this way.

This article will explain why panel orientation is important and why although installing them requires extra effort, it may be better to use horizontal panels.

Note: This article has nothing to do with energy production. In terms of energy production, the shadowless longitudinal panels will generate the same energy as landscape solar panels.

Imagine you want to place 11 solar panels on a typical Colorbond roof.

You can install them like this:

A simple vertical solar installation

A simple landscape solar panel installation

For the roofs in the above two pictures, almost all installers will choose vertical installation. This is because it is cheaper and faster to install in this way. In fact, horizontal installation may take 50% of the time.

why is that. For vertical installation, the installer needs to cut and install 4 sections of rails and use 26 clips to install the panel:

For the horizontal direction, the installer needs to use 10 lengths of rails and 32 panel clamps2:

This figure shows where the mounting rail is usually located in a horizontal installation. On some roofs, 6 rails parallel to the long side of the panel can be used-but the thread pitch and clamping area of ​​the roof may be difficult to achieve.

So, because horizontal installation requires extra effort, why choose horizontal?

The answer is space efficiency. On many roofs, the landscape will allow you to install more solar panels in the same space while still respecting their clamping areas and roof restricted areas.

This means you can get more energy from the same roof.

This is an example of using the same roof as before.

By going longitudinally and taking into account the restricted area of ​​200 mm around the roof edge, we can install 12 panels.

Twelve longitudinal panels will be installed on this roof, respecting the exclusion and clamping area.

For horizontal, we can accommodate 15.

15 landscape panels will be installed on this roof, taking into account the exclusion and clamping area.

Let us now look at an example of a complete roof with some complex roof faces.

Through vertical installation, we can install 47 panels 3:

47 portrait panels suitable for this house (not including the south roof)

For landscape installation, we can install 57. If they were 400 watt solar panels, then an additional 4 kilowatts would be added to the roof.

57 landscape panels are suitable for this house (not including the south roof)

One of the problems with getting the cheapest offer is that the installer does not have time or is inclined to install horizontally.

To install all the solar panels you sell on the roof, they may have to:

Imagine that you have referenced 15 panels for the roof below. If the salesperson has only viewed your roof on Google Maps, they will look easy to fit in portrait orientation.

But when the installer is told to install them and is in a hurry, the following can happen:

Violation of the restricted zone! I always see this when installing in a hurry.

For installers in a hurry, this is the fastest and cheapest way to install these 15 panels. Unfortunately, in order to squeeze them in, the installer violated the 200mm restricted zone, which usually meets the requirements of the Australian solar installation standard AS 5033.

The installation is not compliant and looks terrible. When it rains, the water hitting the solar panels may pour down from the bottom row like a small waterfall, with no drainage ditch at all.

In addition-if the existing screw thread of the roof is not in a convenient location relative to the panel, you may have installed the panel clamp in the wrong position, relative to the short side of the panel-voiding the solar panel manufacturer's warranty.

"Diving board" panel installation. The circled clip is too far from the right hand side of the panel. They may bend in the wind, and if they fail, it will be difficult for the installer to file a warranty claim with the manufacturer.

Sometimes consumers who have competing offers outside of SolarQuotes ask us for help, where salespeople are discrediting their competitors, claiming that the competing offer "the number of solar panels exceeds the capacity of the roof".

Usually, this is because the accusing salesperson did not consider horizontal positioning4.

The future of Australian residential energy is all-electric. In the near future, most households will have electric heating, electric cooking, electric water heaters, batteries and one or three electric cars. In order to power all these things, you need to fill your roof with solar energy. Depending on the shape of your roof, this usually means that landscape solar is the best option. Just don't expect one of the large cheap retailers to offer it as an option.

Endnote: How to compare horizontal and vertical solar panel layouts in 2 minutes

I used SketchUp and the Skelion extension to make the images in this article. If you have an accurate house scale model 5, you can install horizontal or vertical solar panels on the roof within 2 minutes, as shown below:

I am a chartered electrical engineer, solar energy and energy efficiency expert, father and founder of SolarQuotes.com.au. My last "real job" was in the renewable energy department of CSIRO.

There is a problem with horizontal installation. I had to reinstall mine by myself. The solar cells are all connected in series, but arranged in 3 groups, each with 24 batteries, and each group of 24 batteries has a bypass diode. There are 3 diodes for every 72 panels. When the vertical shadow of a tree trunk or pole crosses the solar panel, it will disable one 24 cells at a time, and we only loose 24 cells in the entire string instead of 72 cells. For horizontal installation, vertical shading will disable 6 cells, 2 of 24 cells in each group and disable the entire 72 cell panel. If you have no shadows, this is not a problem. I am willing. I learned the hard way. Fortunately, this is my secondary array, not my main array.

When installing solar panels vertically, horizontally, or a mixture of both, you really need to consider shadows before maximizing the number of panels allowed on the roof.

One of the well-respected Melbourne solar installation companies, highly praised by customers on this website, has set two directions for our upcoming upgrade installation using LG panels and Enphase microcomputers.

Thankfully, most of our long roofs face north and have no hard shadows, so it is easy to arrange two directions to maximize the number of panels.

Designers take time to consider our requirements and use two directions to satisfy them.

We expect them to install our LG/Enphase combination system in the next few weeks.

When using micro-inverters, one per panel is a better solution, but it is much more expensive. Bob

I think you missed an important point when choosing the vertical and horizontal orientation of the panel, and that is the temperature. With corrugated iron roofs and longitudinal panels, the heat under the panels will be higher because there is less space under the panels for two reasons. 1. The rail passes through the corrugation, forming a small dam to absorb heat. 2. The panel is tightly installed on the guide rail, which further restricts the flow of hot air. With corrugated iron roofs and landscape panels, you will get a chimney effect, where hot air flows up and away from the panel unimpeded, constantly being replaced by cooler air from the bottom of the panel. In addition, since the guide rail is mounted on the top of the corrugation and the panel is mounted on the top of the guide rail, you will get a greater gap under the panel. I have read that heat is the enemy of photovoltaics. So I think reducing the heat accumulation under the panel is a good thing. Regards Andrew PS I have no experience with tiled roofs

I think this is an aspect of landscape panels that is often overlooked.

An often overlooked issue is that solar panels do not like heat, and it makes sense that the landscape helps to cool them, especially on metal roofs.

More expensive than what?

Compared with a string system with 1 inverter per system.

Thank you good. This is a rhetorical question. When comparing, compare rather than state.

Yes-this is what I mean in footnote #1. Interestingly, the shadow effect is the opposite of half-cut panels-this is becoming a standard unit configuration. The traditional panel (LHS in the diagram) works best when large shadows invade the long sides. Half-cut panels are best for large shadows that invade from the short side.

Finn. I remember that you did write a post about the shade of shingles. I am keen to compare the vertical and horizontal half-cut and modern shingle panels on the shaded roof. Use Enphase microcomputer.

Hi Finn, I think you dropped a few clips in the "portrait" example-shouldn't it be 26 clips instead of 24? 🙂

Found it, I have fixed the post. I don’t need to know how to count to pass the engineering exam, which is a great idea!

Thank you for the information.... Thank you for improving my understanding of solar edge considerations. I am grateful to you for sharing your knowledge.

Are micro-inverters safer on metal roof houses with attic balconies and metal-colored roofs that are easily accessible? ? ? ?

A string system that is well installed and properly grounded is safe. Grounding will prevent the roof from being charged.

Compared with the 600V DC of the string system, the micro-inverter system will never exceed 230V AC. So it is inherently safer. If something goes wrong-the consequences are not so serious.

For this reason, there are micro devices on my straw hut.

Not mentioned here, but is it possible to use a split design, most of which are vertical, but you have a horizontal finish with the bottom or top row?

The roof issue meant that our panels were divided into north and east + west, but it still did not reach the recommended 133% load. Not a big problem, but I am curious.

Yes-mixing portrait and landscape may be a good choice.

After reading the valuable information of Solar Quotes for a long time and observing the shadows on the roof for more than a year, I finally took the plunge. My installation was very challenging, but the installer (recommended by Solar Quotes) Green Sky Australia was not discouraged and installed 24 x 370W panels and Enphase micro inverters last week. These are split panels, installed in three separate parts of the roof. Of the 11 paintings, the shadows in one section require the lower seven to be portraits, because the shadows occupy the short side and the upper four are landscapes, so they are all suitable. The result looks great. Recommendations for Green Sky will be published separately, explaining how to overcome the challenges.

Another advantage of vertical rails is that they do not collect leaves. The horizontal track accumulates a large amount of debris, which becomes a fire hazard in summer and moisture in winter. It is almost impossible to clear them without removing every panel.

Good shot. I have completed two installations, both under the tailwind of the big gum tree. Fortunately, I stick to the horizontal! I never thought about falling leaves and consequences. The first is to use a micro-inverter. Over time, even though the cable was cut off, it still sagged a bit. The spider weaved a web between the cable and the panel and caught the weird leaves, but most of the space was clean and easy to inspect from the ground. I think if fallen leaves become a problem, the blower can be used from the ground. The second installation has a big gum tree upwind, so far there is no problem of falling leaves under the solar panels. After a gust of wind, the ground was just covered by leaves and branches. The designer is paying attention. Horizontal orientation is the best way, for more than one reason. Regards Andrew

I totally agree that my system is suitable for vertical style. I have many trees on the south side, and there are always piles of leaf fragments that are difficult to remove underneath.

I only installed 24 panels (vertical and horizontal) last week, so I am not qualified to talk about fallen leaves on vertical panels, but the panels are located at least 40 mm above the solar array frame on my peak. The colorbond roof, and 55 mm (approximately) above the valley. I would be very surprised if fallen leaves pile up below such a gap, especially in the case of rain on the Mornington Peninsula. The frame was manufactured by Chiko, used by my installers for many years, and accompanied by a comprehensive Australian structural engineering report. Eucalyptus will fall leaves on the roof, but I don’t think this will be a problem. If accumulation does occur in autumn and the nearby big red wine ash drops its leaves, my leaf blower will deal with this problem because there is a gap between the roof and the panel. I will report on my experience in handling fallen leaves within 12 months.

The fallen leaves I encountered were not between the panel and the roof, but between the installation frame and the roof. The standard corrugated iron roof leaves only a gap of about 25 mm between the valley and the frame. This is where I encountered the problem. Of course, once these valleys are blocked, the leaves will start to become trapped on the high side of the frame below the panel. I found it difficult to move the leaves with a blower; inserting a few panels from the end of a row, it just didn't have enough strength. If you do this often before the leaves start sticking to the roof and between each other, it may work, which is what happens when it rains. If I knew it earlier, I would ask for the horizontal.

As mentioned earlier, in my installation, the distance between the bottom of the frame and the bottom of the valley is 55 mm.

My house has two directions. After installing solar energy on my 2-story steel roof, I regretted it almost immediately. The pigeons moved in the next day and I really liked the horizontal railings! They are great for getting under the panel and sitting on the railing. The sounds they make can only be described as huge, starting at dawn and continuing until sunset.

Now all the birds have been bird-proof, but after that the pigeon stayed for another 4 months because they still think it is home.

If you have a 2-story steel roof, don’t forget to set a price of around $1,700 to get proper bird protection, otherwise you may live in the noisiest house you have ever owned. Especially if you have horizontal rails.

I like my solar energy, but it made me have a miserable year in trying to get rid of these pigeons! I think bird protection is a very undiscussed aspect of solar energy, especially for 2 floors-I didn't intend to go to the roof by myself, it was too risky!

Ah, this is a point raised by no installer when quoting. I didn't know to ask about it 3 years ago. It was a bit disappointing because I wanted more panels at the time, but thought I had reached the limit and they had properly configured them for the roof space. As a result, on the day of installation, some panels on one balcony part of the roof became landscape mode because their edges would exceed 200 mm, and the other was rearranged to get more on the upper floor, but now I want to know if others can configure Also different.

My Longi 370W (2m) panel is installed horizontally, but uses a horizontal (vertical) rack. The installation guide allows this. I had to do some homework to make sure the panel is installed in the clamping area, but it seems to fit my standard roof tile vertical spacing (approximately 600-800mm per 2).

It does use more than 25% of racks and brackets. It is very worthwhile to avoid my southeast facing roof.

Note 1: Not all panels are suitable, some require additional support, and may not be suitable for snow loads due to span-this is not a problem in Perth, Washington. Note 2: Many installers (Budget, Rushjob) told me that this is impossible, and they would rather install on my large roof facing south.

As a retired structural engineer living in a tropical cyclone area, I analyzed the installation of 26 panels on the roof and concluded that the vertical is a bad solution because it causes the track spacing specified by the panel manufacturer to be exceeded or reduced The number of panels on my roof. I believe that the landscape panel orientation is almost always a better structural solution because it makes the roof slat or purlin spacing irrelevant when arranging the railing to meet the panel manufacturer's requirements. My installer did not charge more for the landscape orientation.

I have two directions and the house (clay/tile roof) has 16 longitudinal panels. My shed has 15 landscapes. All use Enphase micro inverters. My installer (G Store Solar) understands the reason for the difference and is very good at communicating with it. The house was installed for about a year and 1/2, and then I installed an additional 15 (and a house battery) on the shed.

Please keep the SolarQuotes blog constructive and useful through the following 4 rules:

1. Preferred real name-you should be happy to add your name to your comment. 2. Put down the weapon. 3. Assume positive intentions. 4. If you are in the solar industry-try to understand the truth instead of selling. 5. Please keep the theme.

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