6kW Solar System Costs, Output, Returns

6kW Solar System Overview

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A 6kW solar system is very close in size to the very popular 6.6kW solar system, which has become a sort of de facto industry standard for many residential single phase homes.

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If you’re choosing between a 6kW solar system and a 6.6kW solar system, we’d always suggest getting the larger option if you’ve got the roof space. The reality is that the inverter is the same, but you’ll be getting 1 or 2 panels of extra PV (solar) generation.

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Just like a 6.6kW system, a 6kW solar system can easily have a battery connected, as most homes will typically have enough solar export in the shorter days of our winter months to fully charge the battery.

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What Actually Is a 6kW Solar System?

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A 6kW solar system is nearly always paired with a 5kW inverter, although some manufacturers (like Fronius) offer a 4.6kW inverter which theoretically could be used as an alternative - more on this below.

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To clear up any confusion, the quoted number when it comes to solar system size is actually the total PV power (solar panels) connected to the inverter. With a 6kW solar system, it’s actually 6kW of solar panels paired with a 5kW or 4.6kW 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 - 14x panels would equate to a 5.74kW system size

…420W panels - 14x panels would equate to a 5.88kW system size

…475W panels - 12x panels would equate to a 5.7kW system size

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The formula is simple: [Panel power (kW) each] x [Number of panels].

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So My Solar System Is Close to but Not Exactly 6kW Total?

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I get it - you’re wondering something like “how can my system size be 6kW if the total PV (solar) connected is only 5.88kW?” Technically, you’d be correct if you called it a 5.88kW solar system, but when comparing options it’s easier to round to the nearest whole kilowatt ie. 6kW.

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If, like most clients, you opt for a 5kW inverter, you’ll technically have some ‘headroom’ to add 1 or 2 more panels to a 6kW solar system, depending on the power of your chosen panels. You could do this at a later date, although the cost of adding only a few panels tends to outweigh the benefit except over a really long period.

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You’re allowed to do this is because 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’re not ‘fully squeezing the lemon’ if you have less than 6.65kW worth of panels connected to a 5kW inverter.

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If you opted for the Fronius 4.6kW inverter however, you’d be limited to having a max of 6.19kW of solar panels connected. For this reason and the fact that it’s not readily available in Australia, we almost never recommend this particular inverter for a 6kW solar system.

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Is a 6kW Solar System Right for Me?

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At the risk of sounding like a broken record, it depends.

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It’s very difficult for us (or anyone!) to say that a 6kW solar system will suit your energy consumption needs and property without properly assessing your situation.

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That said, if your energy bills are above a certain threshold a 6kW solar system may be a great start to drastically slashing them!

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All things being equal, we’d steer you to a 6.6kW solar system instead so you are properly ‘maxing out’ your 5kW inverter’s capabilities and government incentives available to you.