20kW commercial solar power systems: Pricing, output, and returns

20kW solar power systems are becoming an increasingly worthwhile and attractive investment for small to medium businesses across Australia, with payback periods in the 3-5 year range in most parts of the country. This article provides an overview of the ranges of prices, energy yields (in kWh), and financial returns that a business may expect to see from a typical 20kW solar PV system.

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How much does a 20kW solar system cost?

According to data from Solar Choice’s installer network database, a fully installed 20kW system will cost roughly $20,000 – $30,000 as of May 2019. These figures include the up-front ‘discount’/incentive available under the federal government’s Renewable Energy Target for systems under 100kW in output capacity, as well as GST.

(Solar Choice keeps track of commercial solar system prices in our monthly Commercial Solar PV Price Index. Up-to-date figures can be found here.)

With prices in this range, clean & affordable energy is well within the reach of SMEs facing increasing pressure from rising grid electricity prices.

Solar Choice has been keeping track of commercial solar system prices since May 2014 with our regular Commercial Solar PV Price Index updates. While we don’t specifically track 20kW systems, we do track 10kW & 30kW pricing – historic pricing trends for which can be seen in the graphs below:

Average 10kW & 30kW solar system prices between May 2014 and May 2019. (From Solar Choice’s Commercial PV Price Index.)


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How much energy will a 20kW solar system produce?

Depending on a number of factors, the actual power output of a 20kW solar power system will vary. These variables include:

The table below provides a rough indication of the amount of energy that a 20kW solar system will produce per day (averaged over the year) in Australia’s capital cities.

20kW solar system energy yields
Capital City Approx average daily energy production*
Adelaide 72-82kWh
Brisbane 78-82kWh
Canberra 72-82kWh
Darwin ~88kWh
Hobart 58-66kWh
Melbourne 62-72kWh
Perth 80-88kWh
Sydney 68-76kWh

*Assumes north-facing with no shading, 75% system efficiency. Information via PVWatts & Bureau of Meteorology

Keep in mind that the figures in this table are annual averages – daily output figures will generally be higher in the summer and lower in the winter due to the difference in the length of days. In the winter, a system may generate 20-40% less energy, while in the summer it may generate 20-40% more.

Is 20kW the right solar system size for your business?

Determining the right size solar system for your business essentially comes down to three factors:

  • Roof space available: A 20kW system will require at least roughly 100-136m2 of area, but possibly more depending on the wattage of the panels and whether the they require tilt frames.
  • Your energy consumption habits: In many places in Australia, solar feed-in credits are not paid out for energy sent into the grid by solar systems over 10kW in capacity; this means that any solar energy that your system produces that you cannot use directly is of no financial benefit to you. It is therefore important to ensure that the system you ultimately select is sized to meet your business’ energy consumption levels and habits.
  • Your budget: If you have enough roof space to install the maximum recommended solar system size, then it comes down to whether you have the budget to invest in a system.

What is the typical ROI and payback period for a 20kW solar system?

According to our own data from nearly 300 business cases compiled in 2019, payback periods for appropriately sized commercial-scale solar systems in Australia are around 4 years on average, with internal rates of return (IRR – similar to ROI but more sophisticated) easily hitting 20-30% in every state & territory in the country.

Solar Choice runs tenders for commercial projects across Australia.

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