How the iStore battery works
The iStore S1 is a stackable DC-coupled battery that pairs with an iStore hybrid inverter (single or three-phase, 5 to 25 kW across the range). The inverter handles solar, battery and home loads; the battery doesn’t invert power on its own.
During a grid outage, with the right backup equipment, it can support selected circuits you’ve nominated. You monitor charge level, solar and household use from the iStore app.
Which iStore battery size suits your home
Start with what your home draws between sunset and sunrise, because that’s the gap the battery is filling. Your Synergy bill or app will show it. Add a margin for cloudy days and anything you plan to add (EV, pool pump, overnight air-con).
For example, a home using around 10 kWh overnight would get through on the 13.8 kWh IS-BATT-14000-S1 with headroom; a larger household or one with an EV usually wants the 20.7 kWh IS-BATT-21000-S1.
Then the inverter: if you want to add stacks later, don’t start on the single-phase 5000 or 6000, which support one stack only. For the WA rebate, the amount scales up to 10 kWh usable, so any stack of 10 kWh or more receives the maximum.
iStore S1 battery sizes
IS-BATT-7000-S1
IS-BATT-14000-S1
IS-BATT-21000-S1
Scale up later
iStore S1 battery at a glance
Rebates on an iStore battery in Perth
The iStore S1 range sits in the eligible band for both the federal discount and the WA scheme.
- Federal discount: applied up front through STCs. From 1 May 2026 the factor is tiered: 100% on the first 14 kWh of usable capacity, 60% from 14 to 28 kWh, and 15% from 28 to 50 kWh. The rate steps down every six months and the scheme ends in 2030. Install date, not contract date, sets the rate.
- WA Residential Battery Scheme: for Synergy customers, the rebate scales between 5 and 10 kWh usable, up to $1,300 at 10 kWh; any battery above 10 kWh receives the maximum. You must commit to a VPP product with Synergy or Horizon Power.
- Synergy Supported Solutions List: the IS-HYB-1PH and IS-HYB-3PH series are listed with a DER-Storage client, the entry the WA scheme relies on.
What installation involves
Home assessment
We visit to inspect your solar system, switchboard and the proposed battery location. We discuss your evening power use, then recommend a capacity and a position that stays accessible and within temperature guidelines.
Compatibility check
We check whether your existing inverter can work with the battery or whether an inverter change is needed. You get a clear outline of the components and how they work together before any work begins.
Choose backup circuits
Backup only works if it is set up for it. You choose between essential circuits only or a wider set, and we wire those circuits to the battery. What stays powered depends on capacity and wiring.
Installation day
Our technicians mount the unit in a shaded, ventilated position, fit isolators and route the cabling between the array, inverter, battery and switchboard. Every connection is tested before commissioning begins.
Network approval
The installation is documented and connected to meet Australian standards and Western Power network requirements. Correct isolators, testing and documentation are provided for meter approval, with Synergy as the energy retailer.
Commissioning to AS/NZS 5139
We commission the battery to the relevant standards, including AS/NZS 5139. We set the charge and discharge settings, connect the monitoring and confirm the system stores and releases energy correctly.
For how this kind of job is planned, wired and commissioned, see our home battery installation service.
Further reading: Battery Rebates WA: Federal + WA Scheme Calculator
Things to know before you buy
Pros
Add capacity as you need it. Start with one module and add up to three per stack, with up to four stacks per compatible inverter (82.8 kWh).
The warranty is easy to model. The 15-year warranty is backed by 28.84 MWh throughput at 60% end-of-life, so you can model the duty cycle.
Built for sheltered outdoor installs. LiFePO₄ cells and an IP66 rating allow a sheltered outdoor install if your site needs it.
Fits into a wider range. The battery is part of an iStore range that includes a hybrid inverter and an EV charger, which is useful when planning future upgrades.
Things to consider
You can’t buy the battery on its own. It needs a compatible iStore hybrid inverter. If your current inverter isn’t on that list, factor an inverter change into the quote.
Blackout backup needs separate equipment. With the right backup gear and wiring, the battery can supply selected essential circuits during an outage. Decide which circuits at quote stage.
Monitoring must stay connected for the warranty. It is a warranty requirement that the battery stays connected to the iStore monitoring platform. Keep the Wi-Fi on and let us know if it drops out.
Install has a 31-day window. Under the warranty, installation must be completed within 31 days. We book the install date before the hardware arrives.
Single-phase inverter choice limits scale. The IS-HYB-5000-1PH and IS-HYB-6000-1PH support one stack only. If you expect to grow past 20.7 kWh usable, pick a larger inverter from the start.
iStore battery questions Perth homeowners ask
Are iStore batteries any good?
The iStore S1 is a LiFePO₄ battery with a 15-year warranty based on 28.84 MWh throughput at 60% end-of-life. The modular design is the main strength; the main consideration is that it needs a compatible iStore hybrid inverter.
How much is an iStore battery?
Installed price depends on which stack you choose (6.9, 13.8 or 20.7 kWh usable), the hybrid inverter it pairs with, your switchboard and backup wiring. We give a written quote after a site visit.
Does Istore do battery replacement?
The battery pack and power module carry independent warranties, and we handle any claim with you through your installer. Where a claim is confirmed, hardware support is arranged under the manufacturer warranty.
How long will a 10kW battery power my house?
That depends on your actual load. For example, a household using around 7 kWh over the evening would get through the night on the 13.8 kWh IS-BATT-14000-S1 with headroom.
Is it better to have more solar panels or a bigger battery?
If you export a lot of daytime solar and buy power back at night, a bigger battery usually gives the better return. If your solar often can’t cover daytime use, extra panels come first.