Orientation - How it affects solar panels

What is the best direction to face solar panels in Australia?

North-facing panels will usually give the greatest energy output. That’s because Australia, being in the southern hemisphere, experiences a sun that is mostly directed from the north. But did you know that facing west will only reduce your solar system’s total annual energy output by about 15 per cent (depending on where you are located and the tilt of your solar system). And this might just be a smart decision.

As you can see from the above graph, North at 30’ tilt is optimal for Sydney to generate the maximum amount of energy over the whole year.

But for many households, maximum solar energy production does not always equate to optimal power saving the most money off your electricity bills.

Firstly you need to know if you are on a flat electricity tariff - you pay the same rate for your electricity regardless of the time of day - or if your rate varies. Electricity networks such as AusGrid, CitiPower, Ergon are encouraging variable or time-of-use pricing.

Ausgrid peak demand times

The major cost in electricity bills (accounting for roughly half), is in fact the poles and wires, which need to be sized to meet peak demand. Hence the push to charge more for electricity consumed at times of peak demand.

Mount solar panels to catch the sunlight from the west in the afternoon, and the panels’ production overall energy production would drop, but it would come at hours when the electricity was is often more valuable during these peak demand periods (often the big air conditioning surge in summer - read more about how to reduce electricity bills using aircon and solar).

Put simply, west-facing solar panels can often produce more power during afternoon peaks, better alleviating pressure on the network.

For example, in New South Wales the peak electricity price at 2pm is $0.3648/kWh, which is roughly more than double twice the standard or shoulder rate just before that time. So orientating your solar panels towards the West can be a smart move.

Secondly, you need to understand when you use your energy. Just because you have to pay $0.48/kWh for energy bought from the grid between 2pm and 8pm, does not mean that they will pay anything like that for energy generated. In fact, if you export your excess solar electricity back to the grid at 3pm you are likely to receive only $0.06/kWh.

Hence you are highly motivated to generate your solar electricity when you are generally using energy. If you have a lot of energy consumption mid morning, you should orient some of your solar panels to east. If you have a constant amount of energy consumption during the day you might be best served by placing some panels facing east, some facing west, and even at different tilts to effectively flatten out your energy generation profile.

Basically the name of the game to minimise your energy bill is to give as little of your precious solar energy back to the grid as possible.

Maximising self-consumption will become an even more important in the years ahead should state governments continue the trend of lowering feed-in tariffs and increasing peak energy rates. it might even be a smart idea to install batteries to store your energy rather than giving it back to the grid.

How do you know what solar system will be right for your home?

Firstly, make sure you get a few quotes from Clean Energy Council (CEC) Code of Conduct approved solar retailers. Secondly make sure they take into account your typical energy usage patterns. And best of all, pre-install an energy monitoring solution such as Solar Analytics that will allow your selected solar retailer to optimise your solar system, and you to make sure they deliver on their promise.

Why wouldn’t everyone point the panels west?

Some homeowners have panels facing north simply because that is the direction of the roof.  Generally you will place the panels flush to your roof in an area that is mostly free from shade.

If either side of a roof is shaded by trees or buildings, you’d obviously choose the other side.

This might be east, north, west or anywhere in-between.

While some solar panel owners are paid time-of-use rates and are compensated by energy retailers in proportion to prices on the wholesale electric grid, many system owners cannot take advantage of the higher value of electricity at peak hours because they are paid a flat rate.

With the tumbling cost of batteries, it is likely that soon the best solution will be to simply cover the whole roof facing whatever direction, store what you need, and enjoys years of minimal energy bills.

How do I know what’s right for my home?

For solar energy system owners, the way to accurately track solar performance is through an active monitoring system.

These will pay for themselves in a short space of time., depending on the size and reliability of a solar energy system.  

With the Solar Analytics Smart Monitor, you can view your energy usage, net electricity bought and sold, where and how you're using electricity.

You can also see your system’s expected versus actual energy generated on a particular day and gauge if your solar panels are operating at optimal energy efficiency.

This helps you to identify if any solar system alterations or repairs are required.

What does this mean for solar systems already installed?

If you were one of the early movers who now enjoys the benefit of a fixed feed in tariff, then north facing at 30 degrees tilt is ideal to maximise your savings.

Changing the orientation of an existing solar panel is possible, however when the cost of having the array shifted is considered, it usually makes more financial sense to buy additional panels or battery storage.  

Panels do not have to be pointed in just one static direction.  A homeowner can buy a device called a tracker that will pivot the panels over the course of the day, like a sunflower, so they always face the sun.

A tracker can raise the output of a panel by 45 per cent. But installing trackers will cost thousands of dollars, require detailed structural engineering, and council approval. For residential houses, trackers rarely make financial sense.  

A cheaper way to get the same number of kilowatt hours may be simply to buy a few extra panels and point them in different directions.

If you have solar panels pointing in different directions, it is important that each group of panels (called a string or sub-array) is connected to its own Maximum Power Point Tracker (MPPT) within the inverter, otherwise you will get poor performance from your solar system.

Alternatively you can use micro-inverters, which optimise every panel, however these are significantly more expensive than the standard wall mounted inverters.

If you already have a solar system and want to make sure it is performing as it should be, active monitoring is the best way to ensure your solar system is working optimally.

Solar Analytics
We are Australian Photovoltaic Engineers, Software Developers, Scientists, Solar Technicians and Designers, all passionate about sustainable energy and the power of solar.
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