Understanding the Synergy bill is the first step to sizing solar properly. The 2026 picture for a Perth household on the standard plan is a retail rate a long way above the export rate. That gap, not the panel brand, is what decides whether a bigger array or a battery does the work.
Figures below come from our Synergy rates article (1 July 2025 WA Government and Synergy figures) and the Midday Saver note. This page is not financial advice. Tariffs move. Check the current Synergy schedule before you sign anything that depends on a cent.
What you pay on Home Plan A1
Most Perth households are on the Synergy Home Plan, tariff A1: one flat rate, all day. As of 1 July 2025 the published figures are a supply charge of 116.05 cents a day and an electricity charge of 32.3719 cents per kWh. Rounded, that is about 32c/kWh and a bit over $1.16 a day before you use a single kilowatt-hour. The short version of this guide said "about $1.10". The 1 July 2025 schedule is the tighter number; both are describing the same daily supply charge, and the schedule wins.
A typical Perth family using 20 kWh a day was put at roughly $2,700 a year in that short version. Using the 1 July unit rate on 20 kWh a day, plus 116.05 cents of supply, lands in the same ballpark. The supply charge is paid whether the house uses solar or not. Solar reduces the kilowatt-hours you buy. It does not remove the daily charge.
The other residential tariffs
A1 is not the only residential option. The Midday Saver and EV Add-On, as written up in the Midday Saver article, are:
- Home Plan A1: 32.37c/kWh all day, plus the daily supply charge above.
- Midday Saver: 8.62c/kWh super off-peak from 9am to 3pm, and 53.84c/kWh peak from 3pm to 9pm.
- EV Add-On: a 19.38c/kWh overnight window for registered EV owners, on top of the underlying plan.
The trap for a solar-only home is the Midday Saver. Solar you use between 9am and 3pm only offsets an 8.62c import. Solar you do not use is exported for a few cents. In the evening, when the array has faded, grid electricity is 53.84c instead of 32.37c. The Midday Saver article's rule of thumb: unless evening consumption is under about 28% of total grid draw, A1 usually costs less. A battery changes that arithmetic, because it can move midday solar into the 3pm–9pm window. A solar-only home often cannot.
What you earn back: DEBS
The Distributed Energy Buyback Scheme pays for exported solar at two rates: about 10c/kWh from 3pm to 9pm and about 2c/kWh outside that window. The 1 July 2025 DEBS schedule graphic on our feed-in article shows the same pair: 10 cents peak, 2 cents off-peak, for South West Interconnected System customers.
Most exports happen off-peak, in the middle of the day, when the house is at work or school and the array is at its strongest. The average exported kilowatt-hour therefore earns something close to 2c, not 10c. Hoping for the peak export rate means having spare solar after 3pm, which in winter is a short window and in summer is the same hours the air-conditioner wants.
DEBS is not an upfront discount. It does not replace the STC discount on the system price. It is a small credit on the bill, and it should not be the reason you size the array.
Why self-consumption beats exporting
The gap between what you pay (about 32c) and what you earn exporting (2c to 10c) is about 30c on a midday export. Every kilowatt-hour you use yourself is worth roughly 3 to 15 times an exported one: about three times versus the 10c peak export, and about fifteen times versus the 2c off-peak export. That is the whole strategy.
- Run appliances in solar hours. Pools, dishwashers, hot water and washing machines on timers move consumption into the generation window. On A1, each of those kilowatt-hours avoids about 32c. On the Midday Saver they only avoid 8.62c, which is why the plan choice matters.
- Size the system for the load you can actually meet. Undersizing leaves you buying 32c units all afternoon. A modest amount of extra generation costs little once you are already on the roof, which is why the 6.6 kW package (14 × 475W, about 29 kWh a day, from $4,290 after the STC discount) is the common starting point, and 10 kW (about 44 kWh a day, from $6,990) is the step for pools, ducted air-conditioning and EV charging.
- Store what you cannot use. A battery turns a 2c export into a later 32c saving. That is why the published typical battery payback on this site is 4–6 years, against a typical solar payback of 3–4 years. Those are ranges for a Perth household, not a quote.
Perth's published yield is about 4.4 kWh a day per kilowatt installed, as an annual average. A 6.6 kW array at about 29 kWh a day matches that. Summer days on that system are listed around 35 kWh and above, winter days around 18 kWh. A design that only works on the January number will disappoint in July.
A battery, the evening peak, and the May 2026 rules
Without a battery, the valuable solar is the solar you use before the evening. With a battery, the same midday surplus can cover the 3pm–9pm period, which is both the DEBS peak export window and the Midday Saver's expensive import window. You stop exporting at 2c in order to avoid buying at 32c, or at 53.84c if you are on the Midday Saver. The battery has to be large enough to reach that evening. A module that is empty by 6pm does not change the 7pm air-conditioner.
From 1 May 2026, new and upgraded systems on the SWIS have a different export choice: a standard export path, or a flexible path that can join virtual power plant products as they open. Systems installed before that date keep their existing arrangements. Export cents and connection rules are now part of the same decision. The plain-language version is the May 2026 connection rules.
What we would check on a bill
- Which plan you are on: A1, Midday Saver, or an EV Add-On.
- Daily supply versus usage. Solar does not shrink the supply charge.
- How much you import after 3pm. That is the slice a battery can move.
- How much you export in the middle of the day, and whether those units are paid at 2c.
- Whether a concession already reduces the bill. Concessions stack with solar; they are not a reason to skip it, and they are not a substitute for it.
If you want the tariff pages rather than this summary, use the full rates article, the DEBS feed-in guide, and the ROI calculator. Bring the bill. The plan name is printed on it, and the plan name changes the answer.
Published 18 April 2026 · CEC Accredited Designer · 20+ years industry experience
