The plain-English answer
A solar battery stores energy. Backup is the part of the system that safely keeps selected household loads—or, in some designs, a wider set of household loads—supplied when the grid is unavailable.
That distinction matters. A grid-connected solar system can switch off during an outage unless it has been designed with backup-capable equipment and an approved configuration. The NSW Government's home battery guide explains that some grid-connected inverters can operate independently during a power outage when they are designed with that backup function.[1]
The first question is therefore not “How many kilowatt-hours is the battery?” It is: what do you want to keep operating, for how long, and what does the final design support?
Two different blackout plans
1. Essential-circuit backup
This design identifies a smaller set of circuits that matter most during an outage. A final scope might include items such as selected lighting, refrigeration, internet equipment or a garage door—but the exact list is a design decision, not a standard inclusion.
It can be a practical pathway where a household wants a defined resilience outcome and needs to control the total load placed on the backup system. The written proposal should identify the backed circuits, the switching equipment, the battery reserve setting and the operating limits.
2. Whole-home backup
Whole-home backup means the design is intended to support the home’s main electrical circuits during an outage. It does not mean that every appliance can run at every setting at the same time for an unlimited period.
For example, air conditioning, electric cooking, a pool pump, hot water and EV charging can create substantial simultaneous demand. A design needs to account for supply phase, continuous and starting loads, battery/inverter output, storage, system controls and any load-management settings.
Sigenergy’s Australian Gateway documentation describes its HomePro SP-F model as supporting 100 A single-phase backup for the entire home when integrated with the relevant system. That is a product capability—not a substitute for checking the Gateway model, supply, system configuration, electrical design and commissioning for a particular property.[2]
The four questions a blackout proposal should answer
What loads are intended to operate?
Ask for a clear answer in the quote: essential circuits only, or a broader whole-home design? If an appliance is important in an outage, name it and ask how its load has been considered. A generic “backup included” label is not enough.
What is the available power at one time?
Battery capacity is measured in kilowatt-hours (kWh): it describes stored energy. Power is measured in kilowatts (kW): it describes how much can be supplied at one time. Both matter.
The NSW Government explains why this distinction is practical: a battery may have enough stored energy for several appliances over time but not enough maximum discharge power for all high-load appliances at once.[1] A final design should therefore state relevant output assumptions and controls, not only battery capacity.
What changes during an outage?
Ask how the system detects an outage, changes to backup operation and reconnects when grid supply returns. Also ask what the household needs to do: for example, whether there are load-management settings, app controls or reserve settings to understand.
What is included in the electrical scope?
Backup can involve more than the battery itself. The final scope may depend on the switchboard, supply phase, cable routes, gateway or EPS equipment, meter/network pathway, battery location, protection, existing solar architecture, access and commissioning. Site conditions can introduce variations, so these items should be written into the proposal rather than assumed.
Can your EV become another energy source for the home?
Potentially—but only where the vehicle and system support it.
Vehicle-to-home (V2H) allows a compatible EV battery to send energy back into the household electrical system. The Australian Government says V2H may let a household power its home during outages and may reduce reliance on the grid at peak times.[3] It also makes the critical limitation clear: not all EVs or charging systems support V2X, and very few EVs in Australia have V2X capability confirmed by the vehicle manufacturer.[3]
A bidirectional EV DC charger is therefore not a blanket promise that every parked EV becomes a blackout battery. Before representing V2H as part of a home design, verify:
- the exact vehicle model, model year and charging interface;
- the vehicle manufacturer’s confirmed V2H/V2X capability and warranty position;
- charger compatibility and current software requirements;
- the electrical and backup architecture for the property; and
- applicable network, regulatory and commissioning requirements.
Sigenergy’s Australian EV DC documentation describes its product as a bidirectional EV-home bridge and states that V2H functionality is limited by the EV’s capabilities. Its published compatibility material also notes that actual performance can vary by region, software version and model year, and that manufacturer confirmation matters.[4]
A useful way to compare blackout proposals
Use the same checklist with every provider:
| Ask for this in writing | Why it matters |
|---|---|
| Exact battery, inverter and Gateway/EPS models | Confirms the actual backup architecture. |
| Supply phase and backup output assumptions | Shows what the design is intended to supply at one time. |
| Essential-circuit or whole-home description | Prevents a vague backup claim. |
| Named backed loads and load-management settings | Connects the design to how the household will use it. |
| Battery capacity, usable capacity and reserve setting | Separates stored energy from the power available to loads. |
| Outage operation and reconnection process | Helps the household understand what changes when the grid fails. |
| EV make/model compatibility check, if V2H is proposed | Avoids inferring V2H from a connector or charger label. |
| Electrical scope, exclusions and commissioning | Makes site dependencies visible before contract. |
| Warranty documents for equipment, installation and EV use | Separates product terms, workmanship terms and vehicle-warranty conditions. |
The ACCC’s solar and home battery guidance is useful when comparing system suitability, contracts, finance and warranties. It is sensible to obtain more than one reputable quote and compare the full written scope—not just the battery brand or headline price.
How to prepare for a blackout-backup assessment
Bring recent electricity bills, existing solar/inverter details, photographs of the switchboard and proposed equipment area, and a simple list of the appliances you would want to operate in an outage. Include planned future loads such as a heat pump, induction cooking, pool equipment or EV charging.
Cable Co’s Energy Assessment can organise those initial planning inputs. It is not a final electrical design, backup approval, vehicle-compatibility confirmation, finance approval or guarantee of an outage outcome. A qualified site review and written scope are still required.
Sources and review date
Reviewed on 26 September 2026 using the Australian Government’s V2X guidance, NSW Government home-battery guidance and Australian Sigenergy product documentation. Product releases, vehicle software, vehicle warranties, standards, network requirements and site conditions can change. Confirm the current position against the specific vehicle, product documents and written design before contracting.
Sources & references
- NSW Government, NSW Home Solar Battery Guide. ↩
- Sigenergy Australia, Home Energy Gateway. ↩
- Australian Government, Vehicle-to-everything opportunities. ↩
- Sigenergy Australia, SigenStor EV DC. ↩