Why You Shouldn’t Install A 6.6kW Solar System In Sydney

6.6kW Solar Systems… The Good, The Bad, & The Ugly

If you are wondering why there are so many 6.6kW solar deals in Sydney at the moment, you’re not alone. We get dozens of phone calls every day from people wanting a quote for a 6.6kW solar system, and increasing we are responding with: why?

Have you gone through the process of sizing up a system to decide that 16 x 415W panels are exactly what you need (if so, here is our 6.6kW solar price guide)?

Or have you been told that you should get a 6.6kW system with ‘premium tier-1 panels’, free Wi-Fi monitoring… and hurry, the sale ends Friday! Here are some examples of what you may see advertised online:

There are two reasons why there are so many 6.6kW solar deals in Sydney.

  1. The energy distributors in Sydney (both Ausgrid and Endeavour Energy) have a regulation that you must have 3-phase power to install a solar inverter that is larger than 5kW. This means that for most houses in Sydney with single-phase power looking to install solar power, you are limited to a 5kW inverter.
  2. You can then oversize the inverter by a factor of 1.3 which results in a 6.6kW array on a 5kW inverter. This will give you an average of around 20-25kWh of solar power a day (more in summer and less in winter), which may actually be a good fit for many households.

Technically, on a perfect day for solar, your 6.6kW solar array will be limited to 5kW of output by the inverter, however, on most days the output of a solar system doesn’t reach the system’s rating, which makes an oversized system like this a good design. In fact, we do it with all of our Enphase Microinverter systems to help maximise the system’s performance:


So far, so good.

But here’s the thing. Nearly all of the top inverter manufacturers such as Fronius, SMA and Enphase have a way to get around this regulation from the energy distributors called solar export limitation. Because the cheaper inverters typically don’t have this as an option, the 6.6kW system size has become dominated by the cheaper end of the market, what is referred to in polite circles as… ‘cheap solar’.

The disaster that is ‘cheap solar’ has given the whole solar industry a bad name. On average, 1 in 5 solar systems inspected by the CEC are deemed defective, but that’s only the tip of the iceberg.

It is estimated that an incredible 1 in 3 solar systems across Australia is no longer supported due to either the manufacturer or the installer no longer being in business, or pulling out of Australia:

With this recent wave of 6.6kW solar installations at ridiculous prices, many are predicting this number of 1 in 3 to grow dramatically over the next few years when all these systems start failing. We have seen the astronomical failure rates of cheaper solar systems over many years now, there is no reason to expect things to improve when the price of these ‘no-name panels’ is now even cheaper.

This is why a 25-year product warranty from a company like LG Solar is not even close to being the same thing as a 25-year power output guarantee that comes with one of these cheap 6.6kW systems.

In fact, one of the main reasons so many solar installers have closed their doors is that they went broke from all of the warranty claims. They simply couldn’t keep up with the number of systems that failed within the first few years after the system was installed.

You can read more about Cheap Solar here, otherwise, let’s get back to the good inverters…

What is solar export limiting?

The best inverters on the market all have a way to limit the amount of excess solar power that is sent back to the grid.

This means that if you have single-phase power, you can install a system that is up to about 10kW. We then program the inverter to limit the amount of excess solar power that can be sent to the grid to 5kW.

Just to be clear, the full output of the system is fed into the home and fully available for you to use. It’s only the excess solar power that is limited to 5kW. So if the system is sized correctly you will very rarely waste any solar power.

Because of this, the average-sized solar system we are installing in Sydney is now quickly approaching 10kW.

Why is the average solar system now so large?

The way people are approaching solar power in 2021 is getting really interesting. The average system we are installing these days is around 8kW to 10kW, both with and without battery storage.

In simple terms, most households are now sizing up a solar system to match their 24-hour energy usage.

Some of the main reasons why so many households are doing this include:

  • The price of solar panels is at a record-low (this also means more people are choosing top-quality panels, thankfully).
  • Most people will be driving an electric or hybrid car within the life of the solar system
  • Energy prices are some of the most expensive in the world, and they continue to rise
  • Battery storage has arrived – around 1 in 2 Solaray Customers are now installing batteries with their solar system, and this number is quickly rising

If you would like to talk through your options with a member of our team, or you are ready for a personalised quote, please fill out the form below and we will give you a call at a time that suits:

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Size Up A Solar System:

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How Does Enphase Make It Easy To Upgrade Your Solar System?


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