Most Perth households are on Synergy’s Home Plan A1 tariff. It’s straightforward: one flat rate, all day, every day. But it’s not the only option, and for households with solar, a battery, or an electric vehicle, it’s probably not the best one.
- Perth has three residential Synergy tariffs: the flat Home Plan A1 (32.37 c/kWh all day), the time-of-use Midday Saver (8.62c super off-peak 9am–3pm, 53.84c peak 3pm–9pm), and the EV Add-On which adds a 19.38c overnight window for registered EV owners.
- Solar-only homes often lose on the Midday Saver. Self-consumed midday solar only offsets the cheap 8.62c rate, while evening grid draw now costs 53.84c instead of 32.37c. Unless evening consumption is under about 28% of total grid draw, A1 usually wins.
- A battery flips the calculation. Charging from solar during the day and discharging across the 3pm–9pm peak window saves roughly $7 per day, about $2,600 a year versus A1, with payback in the 5–6 year range once WA and federal battery rebates are applied.
- Battery-only homes (no solar) can still arbitrage the super off-peak to peak gap for around $6 per day, making a battery viable even where panels aren't an option.
Contents
Synergy offers two time-of-use alternatives that reward you for shifting electricity consumption away from the expensive 3pm to 9pm window. The Midday Saver is the most widely applicable. The EV Add-On is for registered EV owners who want an even cheaper overnight rate. Both use the same basic structure: cheap electricity in the middle of the day when solar floods the grid, and a higher rate in the evening when demand peaks.
This article covers how each plan works, what the rates actually are, and how solar panels and a battery change the maths.
Perth’s three residential tariffs compared
Every Synergy residential customer on the SWIS grid (Kalbarri to Albany, east to Kalgoorlie) can access these plans. Switching is free, takes about five days, and you can switch back any time.
Home Plan A1 | Midday Saver | EV Add-On | |
|---|---|---|---|
Supply charge | 116.05 c/day | 129.23 c/day | 129.23 c/day |
Super Off-Peak (9am–3pm) | — | 8.6151 c/kWh | 8.6151 c/kWh |
Off-Peak | — | 23.6916 c/kWh (9pm–9am) | 23.6916 c/kWh (6–9am) / (9–11pm) |
Overnight (11pm–6am) | — | — | 19.3841 c/kWh |
Peak (3pm–9pm) | — | 53.8446 c/kWh | 53.8446 c/kWh |
Flat rate (all hours) | 32.3719 c/kWh | 32.3719 c/—kWh | 32.3719 c/—kWh |
All rates include GST, effective 1 July 2025. Source: Synergy Standard Electricity Prices brochure.
Home Plan A1: the default
One rate, no time windows to think about. You pay 32.3719 c/kWh whether you run the dishwasher at 11am or 6pm. The daily supply charge is 116.05 cents.
This plan works for households that consume electricity fairly evenly across the day and don’t want to manage when appliances run. There’s no penalty for cooking dinner at 6pm, running the dryer at 7pm, or leaving the air conditioning on through the evening.
The downside: you pay the same rate at 11am (when the grid has more solar than it knows what to do with) as you do at 6pm (when demand peaks and generation costs are highest).
Midday Saver: three time bands
The cheapest electricity available in Perth is between 9 am and 3 pm on the Midday Saver, when rooftop solar across the SWIS pushes wholesale prices down. At 8.6151 c/kWh, that’s roughly a quarter of the A1 flat rate.
The structure is the same every day, including weekends and public holidays. For 18 hours of the day (9am–3pm and 9 pm–9 am), you’re paying less than the A1 flat rate. For six hours (3 pm–9pm), you’re paying significantly more at 53.8446 c/kWh.
Whether you save depends on how much consumption you can keep out of that evening window. For most households that aren’t actively managing their consumption, the Midday Saver and A1 cost roughly the same annually. The Midday Saver only pays off when you shift consumption deliberately or use a battery to avoid the peak rate.
EV Add-On: a cheaper overnight rate for EV owners
Everything the Midday Saver offers, plus a dedicated overnight band from 11pm to 6am at 19.3841 c/kWh. You need a registered battery electric or plug-in hybrid vehicle to qualify.
The overnight rate matters because it’s when most EV owners charge. At 19.38 c/kWh, charging a typical EV with a 60kWh battery from 20% to 80% costs about $6.97. That’s roughly $1.50 per 100km for most EVs, compared to $12–15 per 100km for a petrol car.
For households that also have a battery, this plan opens up a second low-cost window overnight to top up your home battery alongside the EV.
Requirement for both time-of-use plans: you need a smart meter (AMI). If you don’t have one, Synergy will arrange installation or reprogramming when you switch. There may be a meter fee (currently around $101).
This isn’t Synergy being generous. Western Australia has over 550,000 rooftop solar systems, and on a clear day, the SWIS grid has more solar electricity than it can use between about 10am and 2pm. Wholesale prices go negative. The grid operator (AEMO) sometimes has to curtail rooftop solar to keep the system stable.
Synergy’s super off-peak rate reflects this reality. At 8.62 c/kWh, they’re essentially passing through the low wholesale cost of daytime solar to encourage consumption during oversupply. Run your pool pump, dishwasher, washing machine, and dryer between 9am and 3pm and you’re consuming electricity that would otherwise go to waste.
The peak rate is high for the same reason in reverse. The 3pm–9pm window is when solar generation drops off, households ramp up cooking, heating, and entertainment, and the grid switches to more expensive gas-fired generation. The price signal is real: consume during surplus, conserve during scarcity.
Here’s where it gets nuanced. If you already have solar panels and no battery, the Midday Saver can actually cost you more.
Your solar system generates most of its output between 9am and 3pm. On the A1 tariff, every kWh your panels produce and you consume offsets a 32.37 c/kWh grid charge. Switch to the Midday Saver, and that same self-consumed kWh is only offsetting 8.62 c/kWh, because that’s what grid power costs during those hours anyway.
Meanwhile, the electricity you draw from the grid in the evening (when your panels produce nothing) now costs 53.84c instead of 32.37c.
The break-even depends on your evening consumption. If you can keep your 3pm–9pm grid draw below about 28% of your total grid consumption, the Midday Saver still wins because of the cheaper off-peak overnight rate. But most solar-only homes draw a significant share of their grid electricity in the evening.
The solar-only verdict: run the numbers with your actual usage data before switching. Check your Synergy My Account portal for a time-of-day usage breakdown. If your evening consumption is high relative to daytime grid draw, stick with A1.
Image: Daily solar energy yield between 9 am and 3 pm peak periods.
What changes when you add a battery
A battery fundamentally changes the Midday Saver calculation. It turns the 53.84c peak window from a liability into the primary source of savings.
The strategy is straightforward. Your solar panels charge the battery during the day. From 3pm to 9pm, the battery powers your home instead of the grid. Every kWh the battery displaces during peak hours avoids 53.8446 c/kWh of grid electricity. That’s a 21.47c premium over what you’d avoid on the A1 tariff (32.3719c), per kWh, every day.
Battery savings scenario: solar + battery on the Midday Saver
A 13.5kWh battery (the capacity of a Tesla Powerwall 3) charged from solar during the day and fully discharged across the peak window:
Item | Amount |
|---|---|
Peak electricity avoided (13.5kWh × 53.8446c) | $7.27 |
Cost to charge from solar | $0.00 |
Additional supply charge vs A1 (13.18c/day) | −$0.13 |
Net daily saving vs A1 tariff | $7.14 |
Annual saving (approx.) | $2,606 |
Assumes full daily cycle and solar recharging. Actual savings vary with consumption patterns and battery round-trip efficiency (~90%).
Without solar, the maths still works. Charging from the grid during super off-peak and discharging during peak creates a daily arbitrage:
Item (no solar, grid charge only) | Amount |
|---|---|
Cost to charge 13.5kWh at 8.6151c | $1.16 |
Peak electricity avoided (13.5kWh × 53.8446c) | $7.27 |
Additional supply charge vs A1 | −$0.13 |
Net daily saving | $5.98 |
Annual saving (approx.) | $2,183 |
Does not account for battery round-trip efficiency losses (typically ~10%).
Against a post-rebate battery cost of $10,000–$12,000 (after the WA Residential Battery Scheme rebate of up to $1,300 and the federal Cheaper Home Batteries rebate), payback sits in the 5–6 year range for the solar+battery scenario. Well within the 10-year warranty period.
If you have solar, a battery, and an electric vehicle (or are planning one), the EV Add-On plan is worth serious attention.
The overnight rate of 19.3841 c/kWh means you can charge your car for roughly a quarter of the cost of petrol per kilometre. And the super off-peak rate of 8.6151 c/kWh during the day means weekend charging from the grid (when your car is at home) is cheaper still. If your solar system has surplus capacity during the day, EV charging from solar is effectively free.
The combination of solar panels, a battery on the Midday Saver or EV Add-On, and an EV creates a household energy profile where your total energy spend (electricity, heating, and transport) drops dramatically. The discussion isn’t just about shaving dollars off an electricity bill. It’s about the total cost of energy across your home and your car.
For households already on the Midday Saver who then buy an EV, switching to the EV Add-On is straightforward. Same peak and super off-peak rates, same supply charge, with an improved overnight rate. Synergy requires proof of EV registration.
Switch to the Midday Saver if you: have a battery (with or without solar), are home during the day and can shift dishwasher, washing machine, and dryer runs to 9am–3pm, run a pool pump that can be scheduled for daytime hours, or are retired or working from home with flexibility over when you run appliances.
Switch to the EV Add-On if you: meet the above criteria and own a registered EV or plug-in hybrid.
Stay on the A1 tariff if you: have solar but no battery and draw most of your grid electricity in the evening, consume less than about 4kWh of grid electricity per day (the higher supply charge erodes the benefit), or don’t want to manage when you use energy. The A1 flat rate is genuinely simpler.
Log into your Synergy My Account or call 13 13 53. The switch takes about five business days. If you need a smart meter, Synergy will arrange installation.
Before switching, download your interval data from My Account and review your time-of-day consumption. You want to know your 3pm–9pm consumption as a percentage of total grid draw. If it’s under 30%, the Midday Saver will almost certainly save you money even without a battery.
And if the maths points toward a battery as the missing piece, Perth Solar Warehouse can quote you a system matched to your actual usage and tariff. We’re an approved vendor under the WA Residential Battery Scheme, Tesla Premium Certified Installer five years running, and we’ll tell you honestly whether a battery makes sense for your household or not.
Rates sourced from Synergy Standard Electricity Prices brochure and Synergy plan pages, effective 1 July 2025. Battery rebate information from Energy Policy WA and the federal Cheaper Home Batteries Program. Savings are indicative and depend on individual consumption patterns. Perth Solar Warehouse is an approved vendor under the WA Residential Battery Scheme (trading as PSW Energy).
Synergy: Energy plans
