Shifting to a home with solar panels? Right here's what it’s essential know:

With millions of homes across Australia now powered by solar energy, there's a good chance your new home will have a rooftop solar array.

Much research can be done to buy the right solar system for a home. Therefore, it is important that you familiarize yourself with how your solar system works in order to minimize your electricity bills.

How big is the solar system?

First, check the documents that came with the solar system to determine what system size you are.

The size of the system is the rating of each panel multiplied by the number of panels you have. For example, if you have 10 x 300 W panels, you have a 3 kW system.

You also have an inverter in the system. This converts direct current to alternating current so it can be used at home. Usually the inverter is the same size as the panel array or slightly smaller. For example, it is common to have a 6 kW solar system with a 5 kW inverter.

How much electricity will the system produce?

The performance of a solar system depends on where you live in Australia, the direction your roof is facing, the angle at which your panels are, and whether you have any shadows on the panels.

Let's start with where you are in Australia. Different cities across the country get different amounts of sunshine. You can multiply your system size by these Clean Energy Council performance guidelines to estimate your system's performance as a daily average:

Adelaide: 4.2

Brisbane: 4.2

Canberra: 4.3

Darwin: 4.4

Melbourne: 3.6

Perth: 4.4

Sydney: 3.9

For example, if you have a 5 kW system in Sydney, the daily average will be 19.5 kWh (5 x 3.9). This number is a good place to start, but the reality is that your system will be producing a lot more power in summer than in winter. Here is the power of a 5kW system in Sydney broken down by months:

Roof direction

A solar system with a view to the north without shade gives off most of its power in the middle of the day, basically in a bell curve when the sun moves across the sky.

If your panels are installed facing west, this exit will be moved further into the afternoon. If the panels are installed on an east roof, your system will generate more power in the morning and less power in the afternoon.

Inclination angle

The other thing that can affect the output is the angle at which the panels are installed. Installing panels on a flat roof will increase performance in summer and decrease it in winter, while tilted panels or panels installed on a pitched roof will give more performance than average in winter and slightly less in summer.


The last thing to consider is the possible effects of shadow, be it from clouds, trees, surrounding buildings, etc. The shadow does not turn off the system. However, the performance may decrease depending on the darkness. Here is an example of a 5 kW solar system producing electricity on a cloudy afternoon:

An important point in this graph is that the maximum power of a solar system is always below the nominal power of the system. In this example, the 5 kW system produced a maximum power of 4.61 kW which is actually quite high. It is typical for a 5 kW system to have a maximum power of about 4 kW at any one time.

It has to be the right time of day and time of year for the system to generate the maximum amount of electricity, and even then there are a number of efficiency losses that cause the system to perform below its rated capacity. The inverter is typically 96-97% efficient, and things like temperature and air quality all have little impact.

So don't worry if the system is delivering a little below its rated output. This is completely normal and is reflected in our daily performance metrics in the graph above.

Understand how your solar system powers your home

The electricity from a solar system in Australia is fed into the house so that you can use it to generate it. If you do not use the electricity immediately, it will be fed into the grid and you can obtain a feed-in tariff from your energy trader. When you take over the account for your new home, you should reach out to the energy retailers and get a good deal from an energy retailer that offers you low energy tariffs as well as a good feed-in tariff for excess solar power will be sent to the grid.

The more solar energy you use at home, the better. This is because by using solar energy, you are not buying electricity from the grid, which usually costs around 25 to 30 cents per kWh plus GST.

If your solar system has online monitoring, make sure you get the login credentials so you can keep track of how much power your system is generating throughout the day. It is good to have a basic understanding of how much power your system will generate in different weather conditions and at different times of the day.

Some older systems do not have online monitoring. In this case, you can see how much electricity the system is generating from the small display on the inverter. The tricky thing with older systems is that it can be difficult to keep track of the amount of electricity used in the home and the amount of electricity that the solar system covers.

Newer “intelligent solar” systems have consumption monitoring so that you can compare how much electricity you use at home and how much electricity your system produces. If you want to add panels to your system, we will add a consumption monitor to your system so that both the old and the new panels are shown in the online monitoring.

If you have no plans to add solar panels to your system and you are having trouble understanding the small display on an old inverter, your best bet is to buy a solar monitor like the one from Solar Analytics. This can be installed in your meter by an electrician and gives you a complete view of your solar system as well as how much electricity you use at home. Further information on Solar Analytics can be found here: Solar Analytics

Is your system too small? It's easy to add control panels to your system

The solar industry has come a long way in recent years. The prices for new panels are much cheaper and there is still a good government discount for the additional panels you add to an existing system.

With smart solar technology, we can add panels to a system no matter how old the existing system is. If your system is really old and takes up too much roof space, we can remove the existing system for you and install a new one. This is becoming more and more common as we use 370W panels by default. This is a far cry from the 250W panels we installed a few years ago. It can be useful to remove older panels to free up space on the roof for a more efficient system.

If you are unsure of the best way to go about it, please send a request to the Solaray team. We can help you with some suggestions. We are currently receiving a lot of inquiries as to whether we want to add panels to an existing system or replace an older system. It doesn't take long to find the best options for your situation and provide you with a standard price. Of course we do all of this for you, without any pressure to sell.

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