5kW Solar System Costs, Output, Returns

5kW Solar System Overview

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A 5kW solar system is considerably smaller than the typical 6.6kW solar system that has become so popular for residential installations in Australia, but still a decent option for those with lower energy bills or limited roof space.

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A 5kW solar system would usually have a 4kW or 5kW inverter attached. This means that export limiting is almost never imposed on single phase properties, unless you happen to be in a particularly rural area or an area with too much solar already connected to the grid.

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Believe it or not, a 5kW solar system can still be paired with a battery depending on how much of your energy you consume at night. If, for instance, you are not home during the day (think young professionals with no kids) a 5kW solar system could easily charge a larger home battery like a Tesla Powerwall for you to consume that energy at night time.

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What Actually Is a 5kW Solar System?

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Sometimes a 6.6kW solar system is erroneously referred to as a 5kW solar system, but they’re actually quite different. The reason for the confusion is that a 6.6kW solar system is also typically paired with a 5kW inverter.

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To be absolutely clear, the number quoted when it comes to solar system size is the total PV power (solar panels) connected to the inverter. With a 5kW solar system, it’s 5kW of solar panels and usually paired with a 5kW inverter, although you could technically use a 4kW inverter.

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It’s easy to calculate your system size - simply multiply the number of panels by their rated power.

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For example, if you were using…

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…410W panels - 12x panels would equate to a 4.92kW system size

…420W panels - 12x panels would equate to a 5.04kW system size

…475W panels - 11x panels would equate to a 5.23kW system size

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The formula (for you math nerds out there) is simply [Panel power (kW) each] x [Number of panels].

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So My Solar System Is Close to but Not Exactly 5kW Total?

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If you’re scratching your head at how 12x 410 or 420 watt panels or 11x 475 watt panels can be referred to as a 5kW system, you’re not alone. You’d be technically correct if you referred to them by their exact system size (e.g. 5.04kW), but it’s easier to just round to the closest whole number for ease of comparison.

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Unlike a 6.6kW solar system where the inverter is ‘maxed out’, there’s still some ‘headroom’ with the typical 5kW solar system if you want to add more panels at a later date. Whilst most solar inverters are not rated to have any more than 1.33 times the inverter output connected, and the federal government will also not allow you to claim STCs on any more than 1.33 times the inverter output, you could technically add several more panels later to get your system to a total of 6.65kW total or under.

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However, if you paired your 5kW solar system with a 4kW inverter, the maximum solar you could have connected without violating the above rules would be 5.32kW. If you think you might want to add 3-4 panels later on, we’d strongly suggest pairing your 5kW solar system with a 5kW inverter.

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Is a 5kW Solar System Right for Me?

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It depends. It’s really hard to say without assessing your energy bills, usage, and property.

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On the positive side, a 5kW solar system is smaller than the average 6.6kW solar system, so can be a great solution for smaller properties like semi-detached dwellings or cottages with limited roof space.

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If your bills are above a certain amount, and you have the roof space, the only reason you might go for a 5kW solar system would be if your budget did not allow you to purchase anything larger.