If you’re new to solar, start with the money. In Perth, a modern rooftop solar system generates approximately 4.5 kilowatt-hours (kWh) per day for every 1 kilowatt (kW) of panels installed. Based on today’s Synergy Home Plan (A1) usage rate of about 32.37 cents per kWh, along with a daily supply charge that applies regardless, you have the potential to save between $950 and $1,700 or more per year on your power costs. However, the amount depends on how much solar energy you use at home, rather than exporting it.
The “rebate” is what makes the payback faster. It typically appears as an upfront discount on your solar PV installation invoice—more like an instant discount than a mail-in rebate.
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What “Zone 3” means
Zone 3 isn’t a weather zone or a council boundary. It’s a solar “postcode zone” used to calculate the federal solar discount (Small-scale Technology Certificates, or STCs). Most Perth and Bunbury postcodes fall into Zone 3, which uses a zone rating of around 1.382 in the STC calculation.
Think of the zone rating as a location “multiplier” that reflects how much sun your area typically gets. More sun = slightly more certificates = a bigger upfront discount.
Rebate vs incentive (why you should care)
Rebate (what people mean here): the upfront discount you get when STCs are applied to your quote. Incentive (broader term): any program that improves the economics of solar. STCs are one incentive; Synergy’s buyback for exported solar is another (DEBS). Takeaway: your financial result comes from (1) the STC discount at purchase and (2) bill savings every month after installation.
The solar rebate in one sentence
In 2026, the STC discount is still available for eligible rooftop solar, but the “deeming period” (the built-in years of credit used to calculate certificate numbers) steps down over time—2026 uses 5 years.
That’s why two neighbours installing the same size system in different years can see different STC totals on their quotes.
STCs (Small-scale Technology Certificates) are digital certificates created when you install eligible solar. You can create and sell STCs yourself, but most households don’t. The usual approach is to assign (hand over) the right to create/sell them to a registered agent (often your solar retailer/installer), and they give you an upfront discount in return.
Two details matter on a quote:
- How many STCs will your system create (this depends on size, postcode zone, and year)?
- What dollar value is being used per STC (this is the “STC price” your installer is using to convert certificates into a discount). At the time of compilation, PSW uses $38.
There is a formal fixed-price option of $40 for STCs through the STC Clearing House (excluding GST). Market prices often hover around this level, so reputable quotes typically use a conservative “locked” STC value to minimise surprises. You can refer to the table above for a quick guide on common PSW solar system size rebate values using a 475W residential solar panel, calculated by multiplying system sizes by the locked STC value of $38.
Array size x 475W panels | STCs 2026 | Rebate 2026 |
|---|---|---|
3.8 kW | 26 | $998 |
6.6 kW | 46 | $1,746 |
10.4 kW | 75 | $2,744 |
13.3 kW | 92 | $3,492 |
19.9 kW | 138 | $5,199 |
26.6 kW | 184 | $6,985 |
39.9 kW | 276 | $10,477 |
99.7 kW | 689 | $26,192 |
For those who are particularly curious, there is a formula for calculating the solar rebate:
Multiply the combined watts of your solar array (under standard test conditions) by 1.382. Then multiply that result by the current Small Technology Certificate (STC) multiplier, which is set for 5 years as of the 2026 calendar year. Finally, divide the result by 1000. The final figure represents the maximum number of Small Technology Certificates that your solar energy system may be eligible for.
1.1 Example calculation: 6.6 kW solar array rebate
Solar Array Combined Watts (6650) x 1.382 x 5 (years) / 1000. The resulting number is the maximum number of eligible STCs.
(6650 x 1.382) x 5 / 1000 = 46.
The number of Small Technology Certificates (STCs) for a 6.6 kW system installation in 2026 is 46. Multiply this amount by the locked conservative value of $38.
Rebate: 46 STCs x $38 = $1,746
1.2 Example: Rebate translated as a point of sale x PSW
~6.65 kW system in Zone 3, STCs shown and deducted:
- STC certificates: 46
- STC value used: $38
- STC total rebate/discount: $1,748
- Total including GST: $6,738
- Total out-of-pocket after STCs: $4,990
Interpretation: you’re not waiting for money back later—the discount is already baked into what you pay. To eliminate the guesswork, prices on the PSW websites are listed as Total out-of-pocket after STCs.
Step 1: Get a recent electricity bill. You want your usage (kWh) and tariff type so the savings estimate isn’t guesswork.
Step 2: Confirm you’re in “Zone 3” for STCs (most Perth/Bunbury postcodes are). Your installer should do this automatically, but you can verify the information via the official postcode zone tables if you want certainty.
Step 3: Request that the STC discount be itemised. A clean quote displays: the number of STCs, the value per STC, and the total STC discount.
Step 4: Sign the STC assignment (if you’re taking the upfront discount). This is the normal “we’ll handle the certificates” pathway.
Step 5: Installation happens; keep your paperwork. If you ever need to prove eligibility, documents matter more than screenshots and sales summaries.
Step 6: Make sure your export payments are set up (If applicable—5 kW inverter limited). Synergy’s DEBS buyback rates (effective from 1 July 2025) pay 10c/kWh for net exports between 3 pm and 9 pm, and 2c/kWh at all other times.
Definitions first:
kW (kilowatt) = the size of your solar system (how much power it can make at peak.
kWh (kilowatt-hour) = what you’re billed for (how much energy you used over time.
A 6.6 kW system in Perth, WA, produces ~6.6 × 4.5 kWh/day, or 30 kWh per day on average over the course of a year, totalling around 10,900 kWh/year.
What those kWh are worth depends on where they go:
• Used in your home: avoids paying ~32.37c/kWh (Synergy A1 usage charge).
• Exported to the grid: earns DEBS buyback, typically 2c/kWh most of the day and 10c/kWh 3pm–9pm.
2.1 Example: A simple, conservative savings range (no battery)
- Low daytime use (about 20% self-use): ≈ $960/year benefit
- Typical mixed household (about 30% self-use): ≈ $1,270/year benefit
- High daytime use (about 40% self-use): ≈ $1,580/year benefit
2.2 Example: “$4,990 out-of-pocket after STCs” from the 1.2 Example
- Break-even: about 3.2–5.2 years (depending on self-use)
- Net gain after 5 years: roughly -$190 to $2,910
- Net gain after 10 years: roughly $4,610 to $10,810
- Net gain after 20 years: roughly $14,210 to $26,610
Estimates: using Synergy’s 2025/26 import price and DEBS rates; your actual result depends heavily on when your appliances operate as part of your energy profile. The solar rebate accelerates the payback of a solar array investment, and the real financial benefit accumulates in years 3 to 5, depending on product selection.
Is this too complicated?
It doesn’t have to be. There are two directions customers will take to claim the solar rebate
A) Path of least resistance. If the quote is transparent and the STCs are applied as an upfront discount, you generally sign an STC assignment, and the agent handles the creation/sale pathway.
B) Highly complicated. Choosing to trade STCs through the clearing house will overcomplicate the situation, as regulations require comprehensive verification of STC generation. Solar companies use specialised software to reduce the barriers associated with this process
Will I actually save money?
Yes—if you use a meaningful share of your solar during the day. Export payments are relatively small (2c most of the time), so solar rewards households that shift dishwasher/hot-water/, pool pump/laundry/airconditioning into daylight hours.
Consider adding a battery to offset the remaining unavoidable evening consumption. State and federal battery rebates now make storage adoption more affordable than ever.
What if I make a mistake applying?
PSW and most solar companies don’t facilitate customers applying for or claiming their own STCs via the clearinghouse due to the high likelihood of extended complications.
Therefore, most mistakes happen at signing, not “applying.” The key is understanding what you’re agreeing to: (1) the STC estimate, (2) the STC value used, and (3) any clause allowing the price to rise if STCs can’t be created/transferred or are reduced due to your circumstances.
How to lock-in value without panic buying?
Don’t buy solar just because someone says “rebates are ending/reducing.” The financially smart approach is simpler:
- Demand itemisation: STC count + $/STC + total discount.
- Read the STC/price-adjustment clause.
- Treat the system as a 20-year asset: pick equipment and an installer you’ll still trust when you need warranty support.
Remember: the rebate is a fast start, but your bill savings are the long game.
To begin a solar panel installation, review your recent electricity bill to calculate your daily average usage in kilowatt-hours (kWh/day). This metric will help clarify your energy needs. Decide on a primary goal for your solar system—whether it’s reducing your bills (typically around 6 to 10 kilowatts or more) or maximising your roof’s solar coverage.
Next, obtain at least 2 quotes from solar providers, and compare the total price, the Small-scale Technology Certificates (STCs) line item, and any clauses regarding price changes. In preparation for installation, consider adjusting your energy habits by moving at least one major load, such as hot water, laundry, or dishwashing, to daytime. This change can increase your solar energy consumption and reduce your payback period.
