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Solar Homes NSW

Solar System Output: Rated, Projected and Actual, What's the Difference?

One of the most frequently asked questions we get, and rightly so, is how much will my solar system actually produce? Understanding solar panel and solar system output is vital to good energy management and an effective and educated solar installation. That being said this isn't always the most simple question to answer as many factors are at play, from panel tilt and orientation to the manufacturer of each component there are several elements that contribute to the final output and production figure you see in front of you. There are also more than one measure of this, the rated power output or system potential isn’t always accurate when operating under real world conditions. So let’s dive in and hopefully we can work towards a better understanding of your system output.

Key Takeaways:

  1. Solar Output Varies with Conditions: The rated output of a solar system is based on ideal lab conditions, but real-world factors like temperature, weather, shading, and panel orientation will affect actual performance, often reducing energy generation.

  2. Panel and System Quality Matters: High-quality components, such as efficient solar panels and microinverters, can boost system output beyond standard estimates. Choosing the right products helps optimize energy production and maximize savings.

  3. Inverter Efficiency Reduces Output: Inverters typically operate at around 97% efficiency, meaning even with a perfect solar system, you’ll lose some energy in the conversion from DC to AC.

  4. Seasonal and Daily Variability: Solar production peaks in summer and midday, with performance dropping in winter or on cloudy days. System design, location, and energy goals should all factor into choosing the right system size and components for your needs.

Measuring Solar System Output

The electricity that is generated by your solar panels is measured in Watt Hours (Wh) or more commonly Kilowatt Hours (kWh). This is basically a guide as to the amount of electricity able to be produced by your system at any given time. The key word here is ‘guide’, as different times both throughout the day and the year will bring different external factors impacting the output of the system. 

The overall kW rating of the system reflects results seen in standardised controlled testing, where conditions for production are perfect. Therefore these figures cannot be taken as absolute fact as these perfect test conditions are nearly never replicated in the real world. As a general rule, under test conditions, 1kW of panels in 1 hour will produce 1kWh.

Differences in Panels & Other Components:

Of course like with any industry there are high quality brands and there are more affordable options, each with differing levels of quality. Installing brands that are known for their high efficiency and high performance will obviously provide a greater rate of generation. 1K5° offers a range of products including the Enphase Microinverters, which often will operate at 110% of the predicted rate of production. There is increasing flexibility these days in system sizes and outputs, what it really comes down to is your individual energy goals and the energy generation you need to cover your household needs. 

Ensuring you are installing only high quality, efficient products allows you to match the projected output of the system with the average consumption of youth households. This means greater yearly savings, optimisation of your energy production and usage, all working together to help you maximise your investment.

Peak Output of Your Solar System:

The peak output your solar system is capable of producing can also vary depending on the angle in which your panels are installed. Flat roofs will perform better over summer while tilted roofs have their time to shine during the winter months where they can more easily capture the lower winter sun. 

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Factors Reducing the Peak Output of Your Solar System:

The rating a solar system or panel is given is a reflection of tests undergone in perfect conditions in a laboratory. In the real world this is rarely the case, there are a number of factors that can potentially affect the performance of the system, such as: 

  • Dirty solar panels - dirt and debris build up blocks the amount of light reaching the PV cells.

  • Temperature - Heat and sunlight, although usually associated with each other are not the same thing when it comes to solar. While lots of sunlight is a good thing for your panel array, operating in heat or hotter than usual conditions can in fact lower the overall efficiency of the panels. 

  • Haze/Pollution - pollution in the air can also be a limiting factor in how much sunlight is able to reach the surface of the panel and be absorbed in order to generate electricity. 

  • Weather - this is somewhat self-explanatory, overcast or rainy days with low levels of sunlight will have a negative impact on solar production. 

  • Time of Day/Year - different times of day come with different levels of sunlight, this is also true throughout the year with higher production seen in summer than  in winter. 

  • Patchy Shade - patchy shade from trees, other buildings or even cloud cover can have you seeing dips in production throughout the day. 

Another major factor is your chosen inverter, it is normal to see an efficiency loss when converting your energy from DC to AC. This makes choosing a good quality, reliable and high efficiency inverter an important part of the installation process. Most inverters have an efficiency of 97%, let’s take a look at what this looks like in the real world, for example let’s say we have a 5kW system in a perfect world that has a peak output of 5kW, pair this with an inverter with good efficiency of around 97%, your overall output is already sitting at 4.85kW.

The Output of Different Solar System Sizes

This may all seem confusing at a first glance but let’s have a look at examples of common system sizes in Australia today and their projected vs actual output in order to get a better grasp on this concept. 

The Output of a 5kW Solar System:

A common misconception when it comes to system output is that a system will produce its rated size. Like we discussed above this isn’t always the case due to external elements. In reality your system will produce slightly less than the rated capacity. For example on a sunny, good production day, the peak output of a 5kW system will usually sit around 4 - 4.7kW. The Clean Energy Council estimates that over the course of the day a 5kW solar system will produce around 19.7kWh. In our opinion this isn’t entirely accurate, with good quality components and a well thought out system design you can achieve much more. In the 5kW systems we’ve installed, on a low production day of around 4.06kW, over the course of the day the system has been seen to produce around 24.2kWh. 

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The Output of a 7kW Solar System:

The Clean Energy Council Guidelines state that the output of a 7kW solar system, facing North, sits around 28kW per day. In our opinion this is a rather conservative estimate. In real world examples we’ve seen, where customers are installing good quality, trusted solar components designed to generate energy efficiently, and these components are installed with care for the energy habits of the home, the sun visibility, roof layout and any potential shading issues in mind, then a 7kW solar system has the potential to generate 35 - 40kWh over the course of the day. 

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The Output of a 8kW Solar System:

The estimated daily output of a North facing 8kW solar system is 32kWh (estimated by the Clean Energy Council). For an 8kW solar system you can expect the peak output to fall around 6 - 7kW in the middle of the day, although the peaks may vary depending on the weather. The graph below depicts the impact of cloud cover on an 8kW solar system throughout the day. 

By installing highly efficient brands you can expect to see significantly more power than the CEC’s estimate of 32kWh per day. For example when installing an Enphase system you could potentially generate 40kWh on a sunny day as Enphase Microinverters are rated to deliver 10% more power than standard inverters.

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40kWh is a lot of electricity, most likely more than your home will need, there are a couple of ways you can mitigate this. The first is of course solar storage, by installing a solar battery you can store this excess energy for later use when solar production is low. The other option that suits a lot of homes is a split panel array, allowing for different sections of the set up to see peak production at different times of day, helping to spread the load more evenly and align the times of maximum production with the times of maximum consumption more easily. 

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The Output of a 9kW Solar System:

The CEC estimate for a 9kW solar system installed with a North facing orientation is around 35kW, although system design and panel quality can influence this figure. The solar systems we install usually produce above this estimate as we only install high quality components with maximising your solar investment a priority. Many of our customers experience an average output of 110% compared with the estimate. On a sunny day a 9kW solar system can even generate over 50kWh of electricity, far more than you’ll ever need. 

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The Output of a 10kW Solar System:

The Clean Energy Council estimates a North facing 10kW solar system will see an average of 39kWh of electricity generated per day. Again, as previously mentioned, utilising high performance powerful components you can achieve an average daily production of around 60-70kWh. 

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The Output of a 12kW Solar System:

The estimated average daily production of a 12kW solar system, according to the Clean Energy Council, is around 48kWh. On a bright summer day, with a solar system optimised for your property you could potentially see over 65kWh of power. This is a great deal of power for one household over the course of a day, you may want to consider one of the options discussed above, such as splitting your panel array or installing a storage solution allowing you to maximise consumption and minimise waste.

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The Output of a 15kW Solar System:

A 15kW solar system, north facing in Sydney has the potential to generate over 60kWh daily. This is more of a general estimate, on those extra sunny days with great production you could even expect to see 90kWh of energy generated. 

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Let’s Look at a Larger Example: a 20kW Solar System

As a general rule you can expect a 20kW solar system to output around 80kWh per day although this figure can change depending on factors such as

  • The location of the system

  • The orientation and tilt of the panels

  • Any partial shading the system may be prone to

  • The operating temperature, the higher the quality of panel the better they’ll perform on hot and sunny days

  • Whether the solar panel capacity is correctly matched to the rated capacity of the inverter

  • The quality and performance of the components installed

And of course, the time of year will play a big part in the overall performance of the system. In summer a 20kW system may produce up to or over 100kWh, whereas in winter it may only produce 60kWh.

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To Sum it All Up

Determining the output of a solar system is not as simple as 5kW solar system = 5kW of output. There are a number of factors at play that can significantly influence the peak output of the system including location, orientation, the chosen products and components and of course the time of year and day. The estimates of system performance you’ll hear often aren’t accurate. For example your system size rating will rarely be achieved in the real world due to external environmental factors and the estimates you receive from organisations like the Clean Energy Council are often too conservative as they don’t properly reflect the quality of components and system design. 

FAQ

Frequently Asked Questions about Installing Solar Power

Why doesn’t my solar system produce the exact amount promised by the manufacturer?

The rated output of your solar system is based on lab conditions that are rarely replicated in real life. Factors like temperature, shading, weather, panel orientation, and inverter efficiency all affect your system's actual performance, which typically results in lower output than the rated capacity.

What’s the impact of using an efficient inverter on my solar system’s performance?

A high-efficiency inverter reduces energy loss when converting DC to AC power. While most inverters have about 97% efficiency, using a top-performing inverter can ensure you get the most out of your solar system, improving overall output.

How can I maximize the energy output of my solar system?

Choosing high-quality panels and inverters, ensuring proper system design, and positioning your panels for optimal sun exposure are key factors. Also, regular cleaning of the panels and addressing shading issues can help improve energy production.

Does my solar system’s output change throughout the year?

Yes, solar output varies depending on the time of year. In summer, your system will generate more electricity due to longer days and more sunlight, while in winter, production will typically decrease due to shorter days and lower sun angles.

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