Is a 6.6kW sufficient for my house?
A 6.6kW system seems to be the one most visible on social media. But, is a 6.6kW sufficient for my house?
More often than not, this is the simplest size to install as there is no additional hardware required from the electricity distributor or any complex approvals in place. You may ask why there is a larger array of panels than the inverter size. Further on we explore the amount of power this system size will generate but to summarise briefly, with seasonal and daily variables in the output of the system, it is rare that the full 5kW the inverter is available to convert occurs (other than peak Summer). So, is a 6.6 big enough for my house?
The number of phases your house has may also contribute to the correct system size. Some areas have a limit on the amount of power that can be exported at any one time, or size limits to the overall inverter capacity, frequently this is 10kVa of total capacity, with 5kW export on single phase and 30kVA and 15kW export respectively on a three phase home.
This blog explores in more detail what system size is appropriate for your house, and whether is a 6.6kW is sufficient for your house? Firstly, there are a number of variables that are important when considering the number of panels or system size required. Your current electricity consumption is the initial factor most first time solar seekers work from, along with the aspect and roof area available.
If you are intent on seeking the best possible return from your solar installation then a decent effort into consuming power through the day is required. Do you have electric hot water that can be controlled through a relay or timer, do you work from home and can utilise power effectively?
Some thought needs to be taken into account for future requirements of the home, are you considering battery storage or an electric vehicle that will increase the power needs. Particular expertise here from a longstanding reputable installer will assist with explaining what is and is not viable long term.
How many panels are required for a 6.6kW system
To work out if a is a 6.6kW sufficient for my house, you would also need to work out how many panel you need and if you can fit them on your roof. As panels have reached new power classes and in many cases physical sizes, a system installed in 2023 will likely consist of fifteen to sixteen panels to make up a 6.6kW system array. Modern panels now exceed 400W for residential applications meaning that far fewer are required overall compared with a 6.6kW system installed a decade ago.
How much power will a 6.6kW system produce
The amount of power that will be produced will be dependent on several factors, firstly the location of the installation e.g. North QLD vs Tasmania will differ greatly due to the amount of irradiance seasonally and annually.
The tilt and the orientation of the panels will also contribute to the overall output of the system. A flat roof installation compared with a North facing roof may reduce the output by 10-30% depending on the time of year. In this example the exact detail of the installation needs to be thoroughly explored by a professional to determine if there may be a benefit present to using tilt frames. In many cases now due to the continuing rising cost of electricity, an East and West facing array of panels may present a better financial benefit compared with an all North facing installation, if the power can be consumed on site, rather than returned to the grid.
Location specific factors such as shade from trees, chimney flues or extractor pipes can affect the output of a system, along with persistent debris etc.
Finally the quality of the equipment installed along with the balance of system that is not generally considered, such as cabling and isolators similar to using quality oils, brakes and tyres for your car.
How much does a 6.6kW system cost?
This will take into account the above variables discussed in terms of equipment used and the installation itself, roof type/height, cable length and size along with any switchboard upgrades to meet current standards.
A professionally installed, reliable system with after care support will generally be priced from $5,500 to $10,000 for a 6.6kW system after the STC rebate. This range is broad as there are many factors involved. To work out if a 6.6 big enough for my house, you would also want to know about the payback period…
What is the payback on a 6.6kW system?
The payback time will depend on the system production and the self-utilisation of the power created, along with your electricity consumption. If all of the power created is consumed on site the payback can be as quick as 2-3 years, whereas if the majority of power is returned to the grid and power consumed at night 5-6 years. A solar professional can determine an accurate payback period by assessing your needs correctly.
In summary a 6.6kW system is a well sized solution for many homeowners with moderate power consumption. For an all-electric home with large electrical appliances such as an A/C, pool or electric vehicle a larger system will likely be required.
In summary, the above points will all help you work out if is a 6.6kW sufficient for my house.
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