Electric vehicles are becoming common in Perth homes. We get asked often how to charge them cost-effectively with solar. The good news is that Perth electricity tariff options suit EV owners well. Solar self-consumption, the Synergy Midday Saver plan, and the EV Add-On overnight rate work together. Most Perth EV owners can charge their car at a low cost without touching their home battery at all.
How Solar and EV Charging Work Together
Your solar panels generate electricity during the day. That energy can go to three places. It powers your home in real time. It charges your home battery for use in the evening. Or it gets exported to the grid at the feed-in rate.
An EV charger plugged into your home draws from that same pool of energy. During the day, while the sun is producing, you can run your EV charger directly off solar generation. After dark, your EV charger draws from the grid, or from the household battery. Drawing from the battery creates a problem, which we cover next.
The goal is to align your EV charging with the times when electricity costs least. That might be your own solar surplus during the day. Or it might be a discounted grid rate at night. Perth’s electricity tariff options make this easier than most people realise.
Why Self-Consumption Matters More Than Ever
Larger solar systems in Perth increasingly face export limits. Many installations are capped at 1.5kW of export to the grid. Some larger systems receive no feed-in tariff at all. This means surplus solar generation, above what you use in real time, largely goes to waste instead of earning you a return.
An EV charger running during the day changes that equation entirely. Instead of sending excess solar to the grid for little or no return, you put it directly into your car. A home battery absorbs the rest. Together, a well-designed system with an EV can push self-consumption very high. Very little solar generation goes to waste.
If your solar system is export limited, charging your EV during the day is one of the best ways to use that generation instead of giving it away. Your car becomes part of your self-consumption strategy.
Why You Should Not Charge Your EV from Your Household Battery
This is one of the most common misconceptions about solar battery systems. A home battery is sized to cover household loads: your fridge, lights, air conditioning, and appliances. It covers these overnight and during grid outages. It is not sized to also charge a car.
A typical EV requires 10 to 20kWh or more to charge from a low state of charge overnight. A household battery system typically holds 10 to 20kWh in total capacity. Routing EV charging demand through the household battery would drain it entirely. That would leave nothing to power your home overnight. It would also shorten the battery’s cycle life, by adding deep discharge cycles beyond what it was designed for.
Your household battery is for household loads. EV charging is a separate demand. It needs its own strategy. Perth’s tariff options make that strategy straightforward.
How to Charge Your EV for Maximum Savings
The most cost-effective approach to EV charging in Perth follows a simple three-step order of priority. Used together, these three steps mean your car almost never charges at the standard peak rate.
Step 1: Charge from Excess Solar During the Day
When your solar is producing and your EV is plugged in, it charges directly from your own generation. This is your lowest-cost electricity. It is energy that would otherwise be exported to the grid at a low or zero return rate, given export limits on larger systems.
Perth’s long sunny days make daytime solar charging highly effective for most of the year. Most modern EVs and home EV chargers support scheduled charging. You can plug in before you leave in the morning, set a charging window, and let the system handle the rest.
Step 1 costs almost nothing. Excess solar going into your EV, instead of the grid, is energy you would otherwise not be paid for.
Step 2: Top Up During the Midday Saver Window if Needed (9am to 3pm — approx. 8.85c/kWh)
If your solar alone does not fully charge the car on a given day, the Synergy Midday Saver Super Off-Peak window helps. It runs from 9am to 3pm. It lets you draw from the grid at approximately 8.85 cents per kWh, around a quarter of the standard peak rate.
This is the same window in which your household battery charges from solar. The system powers your home first. It then charges the battery, then the EV, then exports anything left over. With good solar output and an EV plugged in, very little ends up going to the grid at all.
For current Midday Saver rates and eligibility, visit: synergy.net.au/Your-home/Energy-plans/Midday-Saver
Important: make sure your EV finishes charging before 3pm. The Midday Saver peak rate from 3pm to 9pm is approximately 55.33c/kWh, one of the highest rates available. Schedule your charging to finish within the 9am to 3pm window to realise the savings.
Step 3: Fill Up Overnight on the EV Add-On Tariff (11pm to 6am — approx. 19.92c/kWh)
For anything left to charge, the Synergy EV Add-On tariff provides a discounted overnight rate. It runs from 11pm to 6am, at approximately 19.92 cents per kWh. That is well below the standard peak rate of around 55.33 cents per kWh.
You plug in when you get home, and set the car to begin charging at 11pm automatically. Your household battery handles overnight household loads on its own, charged from solar during the day. The EV and the home battery run as separate systems, with no conflict between them.
For current EV Add-On rates and eligibility, visit: synergy.net.au/Your-home/Energy-plans/Electric-Vehicle-Add-On
Step 3 makes sure the car is full in the morning at a low rate, no matter how much solar was available during the day.
EV Charging Rates at a Glance
Rates are indicative, based on current Synergy published tariffs, and are subject to change. Check synergy.net.au for the most current pricing before you make tariff decisions.
During the Midday Saver on-peak period from 3pm to 9pm, your household battery takes over. Charged from solar during the day, the battery covers household loads through the expensive peak window. This means you are not drawing from the grid at the higher rate. With a correctly sized household battery and proper load management, your home can get through the on-peak hours without touching the grid at all.
How Having an EV Affects Your Solar System Sizing
An electric vehicle adds meaningful demand to your home’s energy profile. Depending on how far you drive each day and how often you charge, an EV can add 10 to 20kWh or more of daily electricity consumption.
If you plan to get an EV, now or in the next few years, it is worth factoring this into your solar system design from the start. A solar system sized purely for your household loads may not generate enough surplus to cover EV charging as well, especially in winter when days are shorter.
The key questions are:
- How many kilometres do you drive per day on average?
- Will you charge primarily during the day (Midday Saver) or overnight (EV Add-On)?
- Do you want solar to cover some or all of your EV charging, or just household loads?
Positive Energy Solutions can model your EV charging demand alongside your household usage, and recommend the right solar system size. In many cases, adding an extra string of panels at installation time costs much less than adding them later.
If you plan to get an EV in the next few years, tell your Positive Energy Solutions energy consultant now. Sizing your solar for future EV demand at install time almost always costs less than upgrading the system later.
Three-Phase Homes and Faster EV Charging
Most home EV chargers in Australia operate on single-phase AC power. They deliver charge speeds of around 7kW. For a three-phase home, a three-phase EV charger can deliver up to 22kW of charge. This significantly cuts the time needed to fill a large battery.
If your home has three-phase power and you are installing an EV charger, it is worth discussing whether a three-phase charger suits your needs. The faster charge rate helps most for households that drive longer distances, have multiple EVs, or want the car fully charged even when they plug in later in the evening.
For homes not yet connected to three-phase power, the combination of solar, battery, and an EV can sometimes justify upgrading the connection. Your Positive Energy Solutions energy consultant can advise whether this makes sense for your situation.
A Different Approach: SigEnergy SigenStor EVDC Mode
The household battery is not the right tool for standard EV charging. But SigEnergy’s SigenStor has a unique feature worth knowing about. EVDC mode allows the SigenStor to charge a compatible electric vehicle directly from its DC output. This bypasses the need for a separate EV charger unit, and reduces the energy conversion losses involved in AC charging.
This is a different use case from routing household battery capacity to the EV. EVDC mode draws from the solar DC input directly, rather than depleting the battery reserve. This makes it a more efficient approach for the right setup.
For more detail on how this works and whether it suits your home and vehicle, see the dedicated Positive Energy Solutions guide to SigEnergy SigenStor EV Charging.
EVDC mode is specific to the SigEnergy SigenStor and compatible vehicles. It is not a standard feature of other battery brands. Ask your Positive Energy Solutions energy consultant if you are interested in this option.
Talk to a Positive Energy Solutions Energy Consultant
The best EV charging strategy for your home depends on your driving habits, your tariff, your solar system size, and whether you have single or three-phase power. There is no universal answer. But the options in Perth are genuinely good. With the right setup, most EV owners can charge their car at a low cost using solar or low-cost off-peak grid electricity.
Positive Energy Solutions can assess your home energy profile, factor in your EV, and recommend the right combination of solar, battery, tariff, and charger for your situation.
Book a consultation with Positive Energy Solutions. We will help you work out the most cost-effective way to charge your EV alongside your solar and battery system.
Related guides
- Adding a Battery to Your Existing Solar System in Perth: 2026 Costs, Rebates, and Inverter Compatibility Guide
- Best Solar Batteries for Perth Homes in 2026
- Is LFP Battery Chemistry Right for Perth Homes? A Closer Look at the BYD Battery-Box Premium HVM
- DC-Coupled vs AC-Coupled Solar Batteries: What Perth Homeowners Need to Know
Frequently Asked Questions
Can I charge my EV from my home solar battery?
It is not recommended. Your household battery is sized for household loads: running your home overnight and during outages. Routing EV charging through it would drain the battery, leave your home without overnight power, and add more discharge cycles than the battery is designed for. EV charging is better handled through a dedicated tariff strategy.
What is the lowest-cost way to charge an EV with solar in Perth?
The best approach uses all three strategies together. Charge from your own solar first, at almost no cost. Use the Midday Saver tariff for any grid top-up during the 9am to 3pm window, at approximately 8.85c/kWh. Fill the rest overnight on the EV Add-On tariff, at approximately 19.92c/kWh from 11pm. This way, your car almost never charges at the standard peak rate.
Do I need a bigger solar system if I get an EV?
Potentially, yes. An EV can add 10 to 20kWh or more to your daily electricity demand, depending on how much you drive. If you want your solar to cover some or all of your EV charging, your system may need to be larger than one sized purely for household loads. Discuss this with your Positive Energy Solutions energy consultant before installing. Adding panels at install time costs less than upgrading later.
What is the Synergy EV Add-On Tariff?
The Synergy EV Add-On Tariff gives a discounted electricity rate for EV charging from 11pm to 6am, at approximately 19.92c/kWh, well below the standard peak rate. You schedule your EV to begin charging at 11pm automatically. It operates independently from your home battery system. You need a compatible time-of-use meter to access this plan. See synergy.net.au/Your-home/Energy-plans/Electric-Vehicle-Add-On for full eligibility details.
Does three-phase power make a difference for EV charging?
Yes. A single-phase home EV charger typically delivers around 7kW. A three-phase EV charger can deliver up to 22kW, significantly reducing charge time. If you have three-phase power, it is worth considering a three-phase-capable EV charger when you install. Speak to your Positive Energy Solutions energy consultant about what suits your driving patterns.
What is SigEnergy EVDC mode?
EVDC mode is a feature of the SigEnergy SigenStor. It lets the SigenStor charge a compatible electric vehicle directly from its DC solar input, without a separate EV charger unit. It is more efficient than standard AC charging, because it avoids extra energy conversion steps. It is specific to SigEnergy and compatible vehicles. See our dedicated SigEnergy SigenStor EV Charging guide for more detail.
About the Author
Jason Wiktorowicz
Sales Manager, Positive Energy Solutions | Perth, WA
Jason has been at the centre of Western Australia’s energy transition for over a decade. As Orchestration Lead on Project Symphony — WA’s largest virtual power plant pilot — and Stream Lead on Project Encore, he worked directly with AEMO, Western Power and Energy Policy WA to shape how distributed energy resources connect and operate on the SWIS. That work included developing and rolling out CSIP-AUS, now mandatory for all new WA grid connections. He also led Emergency Solar Management (ESM), the first program of its kind in WA, VPP for Schools (VPP4S), which provided direct market benefits through Supplementary Reserve Capacity, and REBAR, the WA Residential Battery Rebate scheme.
His earlier career spanned Synergy, Infinite Energy and Curtin University’s Sustainability Policy Institute, where he co-authored peer-reviewed research on net-zero urban precincts, solar integration and peer-to-peer energy trading, published in the journal Urban Planning in 2018.
At Positive Energy Solutions, Jason leads sales with a focus on system design accuracy and long-term performance. Positive Energy Solutions installs solar and battery systems, EV chargers and heat pumps, and holds partner accreditations with Fronius, SigEnergy, iStore and SunPower. Connect with him on LinkedIn.
