7kW solar systems, once relatively uncommon, have grown in popularity in Australia as the average solar system size has increased. A 7kW solar system could be the perfect match for an ordinary household with higher-than-average electricity consumption, or for a small business with accordingly small electricity needs.

Back when Australia’s solar industry began booming around 2008, the most popular (and affordable) solar system size was 1.5 kilowatts (kW), due mainly to the high price of solar photovoltaic (PV) technology. Solar system prices have since come down considerably, however, leading to growth in average system sizes across the nation. 1.5kW systems are now a relatively unpopular choice given the proportionally greater financial benefits possible by investing in larger systems.

These days, depending on your state, the size range for a residential solar system is ordinarily between 3kW and 5kW. As of the time of writing, in NSW (for example) the most popular system size is 5kW (according to data from Australian solar industry analysts Sunwiz)–not far from a system with a capacity of 7kW.

Pricing for 7kW solar systems

On a monthly basis, Solar Choice publishes 2 articles about solar PV system pricing trends from across Australia based data from our installer network; one about commercial solar system prices, and another about residential solar PV prices. These articles are intended to allow solar shoppers to orientate themselves with regard to the normal range for solar system prices, as well as to provide a benchmark for solar industry players. Although these articles do not include pricing specific to 7kW systems (yet), they nevertheless offer insight into how much a solar shopper could expect to pay for a 7kW system.

As of August 2014, the average dollar-per-watt (1 kilowatt = 1000 watts) price for a fully installed 5kW system was around $1.68 ($1.68 x 5000W = ~$8,400), while pricing for a 10kW solar system was around $1.54 ($1.54 x 10,000W = ~$15,400). Making the reasonable assumption that the $/W cost of a 7kW solar system would be somewhere between these two, we come out with an average price of $1.61 ($1.61 x 7000 = $11,270).

Solar Choice Solar PV system prices high low average August 2014

Prices from Solar Choice’s Solar PV Price Index article for August 2014.

Of course, there is much more variation than this in the market–7kW solar systems using lower-priced components will come with a smaller price tag, while offerings from the premium end of the market are, generally speaking, dearer.

You can receive a free and instant comparison of quotes from solar installers in your area by filling out the form to the right of this page. Instant quotes will include systems sized 1.5kW, 2kW, 3kW, 4kW and 5kW, but prices for larger system sizes (including 7kW) are available on request and through consultation with our team.

5kW rooftop Solar PV array, near Tamworth NSWTypical power output 7kW solar system

Depending a number of factors, the actual power output of a 7kW solar power system will vary. These factors include:

-Geographic location and associated climate

Orientation and tilt angle of the solar panel array

The degree to which the panels are shaded by nearby objects

-Operating temperature of the panels (generally a function of climate)

-Whether solar panel array capacity is accurately matched to inverter capacity

-The performance of the individual components (mainly panels and inverter)

As mentioned in the first point above, different areas receive different amounts of sunlight. The amount of sunshine falling on a solar panel array has a direct impact on the system’s power output. If your system is in Sydney, for example, you can expect the equivalent of 4.8 hours of ‘full sun’ (also called ‘peak sun hours’ or PSH) throughout the course of the day. (Keep in mind that this number is the annual average–the system will generate more power in the summer and less in winter.)

A perfectly efficient 7kW solar system in Sydney, for example, would produce about (4.8 ‘peak sun hours’ x 7kW =) 33.6 kilowatt-hours (kWh) of power per day. 

Of course, no system is perfectly efficient, and performance is usually derated to around 77% of peak capacity. This brings output down to about 26kWh. (Check out our solar payback calculator to learn more.)

Payback period & ROI for a 7kW solar system

Payback periods for any size solar system are contingent on a number of factors, but one of the most important ones for homes and businesses going solar these days is ‘self-consumption’. These days, with only low solar feed-in tariffs on offer in pretty much every state, the business case for going solar is based mainly on how much of  the solar power the home or business in question can consume themselves.

Here’s why: If you own a solar system, the power it produces is worth much more to you if you consume itself yourself than if you allow it to be ‘exported’ to the electricity grid. If you self-consume 1kWh of power, you avoid purchasing 1kWh of electricity from the grid, thereby saving anywhere from 18¢-¢27 on your power bill, depending on your location and what your electricity retailer/utility charges you for electricity. By contrast, if you allow the power to be exported to the grid, your electricity retailer is likely to only ‘reward’ you to the tune of 6-10¢/kWh.

So how can you make sure you use as much of your solar power yourself? Step 1 would be ensuring that you get a solar system that is appropriately-sized for your needs. Step 2 would be understanding your electricity usage profile and working to optimise your power usage. (Note that power from a system’s solar panels will automatically go straight into any appliances that are running, and the excess will automatically ‘leak’ into the grid.)

Check out Solar Choice’s solar power system ROI calculator

Want to learn more? Try plugging some figures into our solar system ROI calculator. Self-consumption is just one of the variables that can be adjusted to determine your likely payback time and return on investment.

7kW solar PV system ROI at 70pc self-consumption

© 2014 Solar Choice Pty Ltd

{ 3 comments }

Dr. Ranjith Obeyesekera 9 December, 2015 at 5:16 pm

Very useful information.thank you.

Paul J Camire 21 September, 2014 at 1:57 am

I have a company here in NH who just quoted a 7KW ground mounted system for Just over 30K, with the 30% government tax credit and $3500 of state cash back it came out to a little over 17K our cost. Our electricity bill is on average $150 a month for 12 months. I am 55 yrs old and don’t see the payback of 12yrs as being worth it. I would do all the site work – level area where pads are to be laid, cut trees, and dig trench for electrical from panels to house, and poke a hole thru my foundation for the conduit. Price seems more than excessive don’t you think?

Solar Choice Staff 23 September, 2014 at 3:09 am

Hi Paul. I can’t really comment on the situation in New Hampshire as we service the Australian market. The 7kW system at $30k works out to around $4.30 per watt–that’s definitely on the expensive end for a system of that size installed in most places in Australia. Payback periods here are more in the range of 4-7 years.

Is that the best price you’ve been able to find for your area? And I assume you’re not entertaining the idea of going with a leasing deal?

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