For a household using 22 kWh a day, about $766 a quarter at WA's 33.3c a unit, the calculator puts 10–13kW solar at $7,670 to $12,670 after rebates, and 10–13kW solar + ~15kWh battery at $9,740 to $20,740.
I am an advisor, not an installer and not a lead broker. You pay nothing at any point.
See what my home should costA family in a four-bedroom house, someone home some days, using 22 kWh a day.
A ballpark for one example household, not a quote. The low end of each range is what a competitive installer charges; the high end is a poor quote for the same equipment. Prices are from the same calculator the free assessment uses, with WA rates and rebates, and sun hours are its figure for Western Australia.
Four real households, run through the same calculator this site uses for an individual report. Panels only, no battery, clean roof, someone home some of the time. Prices are after every rebate that applies in Western Australia.
| Household uses | Their quarterly bill | System | After rebates | Saves a year | Pays for itself |
|---|---|---|---|---|---|
| 10 kWh | $403 | 6.6kW solar | $6,050 to $8,050 | $480–$720 | 10+ years |
| 15 kWh | $554 | 6.6kW solar | $6,050 to $8,050 | $640–$950 | 8–10 years |
| 22 kWh | $766 | 10–13kW solar | $7,800 to $12,800 | $980–$1,470 | 7–10 years |
| 30 kWh | $1,008 | 13–15kW solar | $9,550 to $15,600 | $1,290–$1,940 | 6–9 years |
The bill column is what that household actually pays in Western Australia at 33.3c a unit, which is why the same house has a different bill in every state. Savings depend on how much of the generation gets used on site rather than exported, and at 2c a unit for exports that is the number that decides the answer. A household out all day saves less than the figures above; one home most days saves more. Every figure is produced by the calculator, not written down, so it moves when the published rates move.
Willetton is an established southern suburb of family houses, with a lot of owners who have paid them off. Many of these houses may already have had one solar system; for those, the question is upgrading under the 2026 rules rather than starting from scratch.
In Perth, the poles and wires belong to Western Power and the bill, for most homes, comes from Synergy. Willetton is on that network, the South West Interconnected System[1], and its rules are the ones a quote here has to be designed to.
The 1 May 2026 rules. A system installed or upgraded on or after 1 May 2026 has to be able to be remotely disconnected and reconnected in an emergency, and Synergy talks to it using CSIP-AUS. Keep it connected and it can join flexible export or virtual power plant products as they arrive; if you would rather not, or your internet is unreliable, it is set to a fixed 1.5kW export limit. Your own use of your solar is unaffected either way, and systems installed before 1 May 2026 are not affected[1]. Western Power's technical requirements put the static base limit at 1.5kW and allow up to 5kW where the system is managed under an agreement with your retailer[2].
What that means in practice: a quote written now should name an inverter that meets Synergy's requirements and say which way the system will be set up. Exports earn little for most of the day, so size the array to what the house uses, not to the size of the roof.
At the 2021 Census, 89.9% of occupied homes in Willetton were separate houses and 64.6% had four or more bedrooms, against 44.7% across Western Australia. 39.3% were owned outright and only 19.7% rented.[3]
Settled owners in big family houses.
Things worth knowing before an installer walks the roof:
All of that describes the area, not your house. Two homes on the same street can be completely different jobs. Put your address in and the assessment works off the actual property rather than a town average.
The 1 May 2026 rules apply to upgrades as well as new systems: adding a battery or another inverter brings the site under them[1]. An older inverter that cannot meet them may need replacing, and that should be on the quote, not discovered after.
A like-for-like inverter replaced under warranty does not trigger the new requirements. Anything more than that probably does.
The WA battery rebate, up to $1,300 for Synergy customers, comes with a condition: the battery has to join a virtual power plant and be on Synergy's supported list[4]. That means Synergy can draw on it at times, under the program's terms. Read those terms before you sign, and make sure the battery on the quote is on the list, or the rebate is not available.
These are examples, not an average for Willetton. They are picked to show how the answer moves for the kinds of household the census shows are common here. Clean roof, no shading, WA rates and rebates, and the battery prices assume it is installed before the federal battery discount steps down on 1 January 2027.
| Option | System | After rebates | Saves a year | Pays for itself |
|---|---|---|---|---|
| Change plan and cut waste first | No system | $0 | $150–$460 | Nothing to pay back |
| Solar panels only | 10–13kW solar | $7,670 to $12,670 | $980–$1,470 | 6–10 years |
| Solar plus a 10kWh battery | 10–13kW solar + 10kWh battery | $7,500 to $18,100 | $1,710–$2,440 | 4–9 years |
| Solar plus a 15kWh batteryPays back fastest | 10–13kW solar + ~15kWh battery | $9,740 to $20,740 | $2,050–$2,680 | 4–8 years |
Solar plus a 15kWh battery. It pays back fastest of the options open to you, which is the only measure here that accounts for what the thing actually costs.
Before any of it: get onto a competitive retail offer. It costs nothing, it takes an afternoon, and on a bill your size it is worth roughly $150 to $460 a year. Every payback below gets shorter once you are paying less per kWh, so it is worth doing first either way.
| Option | System | After rebates | Saves a year | Pays for itself |
|---|---|---|---|---|
| Change plan and cut waste first | No system | $0 | $110–$330 | Nothing to pay back |
| Solar panels only | 6.6kW solar | $5,960 to $7,960 | $790–$1,180 | 6–8 years |
| Solar plus a 10kWh batteryPays back fastest | 6.6kW solar + 10kWh battery | $6,240 to $14,140 | $1,390–$1,790 | 4–9 years |
Solar plus a 10kWh battery. It pays back fastest of the options open to you, which is the only measure here that accounts for what the thing actually costs.
Before any of it: get onto a competitive retail offer. It costs nothing, it takes an afternoon, and on a bill your size it is worth roughly $110 to $330 a year. Every payback below gets shorter once you are paying less per kWh, so it is worth doing first either way.
"Pays for itself" is the range between a competitive quote and a poor one for the same equipment, and 10+ means not inside ten years. The battery ranges are wide for the same reason. Your own usage, roof and timing will move every figure here, which is what the free assessment works from.
Applied by the installer as a discount on the quote, not something you claim. It scales with system size: on the 10–13kW solar in the first example above the calculator counts $2,330. It falls a little each year until the scheme ends in 2030.
There is no state rebate on solar panels in WA, but there is one on batteries: up to $1,300 for Synergy customers and up to $3,800 for Horizon Power customers, still open in May 2026[5]. To get it, the battery has to join a virtual power plant and be on Synergy's supported list, and low- and middle-income households can borrow up to $10,000 interest-free for solar and batteries[4]. The calculator includes the $1,300 Synergy rebate in every battery price on this page.
The federal Cheaper Home Batteries Program applies on top. On a 10kWh battery the calculator counts $2,520. The rate is set by the date the battery is installed, not when you order it, and it steps down on 1 January 2027 and every six months after that[6]. Larger batteries earn less per extra kWh: the full rate applies to the first 14kWh.
WA's Distributed Energy Buyback Scheme pays Synergy customers 10c a unit for exports between 3pm and 9pm and 2c at other times, on up to 50 units a day[7]. The calculator assumes 2c a unit, the rate for most of the day, which is why every example on this page is decided by how much power the house uses itself. For the price you pay, it uses Synergy's regulated Home Plan (A1) rate of 33.3c a unit from 1 July 2026[8]; your actual rate depends on your retailer and plan, and time-of-use plans and Horizon Power customers will differ.
The full breakdown, with dates, is in WA solar rebates explained.
Already holding a quote? This is how I read one, line by line.
For the first example household on this page, 22 kWh a day, the calculator puts 10–13kW solar at $7,670 to $12,670 after WA rebates, and 10–13kW solar + ~15kWh battery at $9,740 to $20,740. The range is the gap between a competitive installer and a poor quote for the same equipment. Your own figure depends on your usage and roof, which is what the free assessment works out.
Western Power. Perth is on Western Power's network, the South West Interconnected System, and most homes buy from Synergy. Systems installed or upgraded from 1 May 2026 must be remotely manageable in an emergency; stay connected and you can join flexible export or VPP products, or take a fixed 1.5kW export limit. Western Power's maximum is 5kW where the system is managed under a retailer agreement.
Yes. Adding a battery or another inverter counts as an upgrade, so the system has to meet the 1 May 2026 requirements: able to be remotely managed in an emergency, or set to a fixed 1.5kW export limit. A like-for-like warranty replacement of an inverter does not trigger them.
The installer, and only when a job completes. Never the homeowner. No installer can buy placement, and nothing about you reaches one until you ask me to make the introduction.
About a minute. You get the system size, what it should cost, and what it saves. No one calls you unless you ask.
Start My Free CheckIndependent explainers on the parts of this that actually change the answer.
Prices, savings and paybacks come from this site's calculator, using WA rates verified 2026-10. Everything else is from the sources below, read on the date shown. Rules and rebates change, so check the source before you rely on one.