Yes, a battery system can power a whole home, but only if two parts are sized correctly. The inverter limits how much power you can draw at once (kW). The battery limits how long you can keep drawing it (kWh). A system can have plenty of stored energy and still trip when the well pump, dryer, and heat pump start together. A powerful inverter with a small battery has the opposite problem: it will run out within hours.
This guide explains how whole-home storage works in Canada, how to size it, and which system types fit different homes.
Whole-home backup vs. essential-loads backup
| Essential-loads backup | Whole-home backup | |
|---|---|---|
| What stays on | A subpanel with selected circuits: furnace fan, fridge, sump pump, lights, internet | The main panel, so every circuit you choose to run |
| Inverter size | Smaller | Larger, or several in parallel, to cover peak loads and motor starts |
| Battery size | Smaller | Larger, especially for multi-day outages or electric heat |
| Typical equipment | Hybrid inverter and a critical-loads panel | Hybrid inverter with whole-home passthrough or a transfer switch, plus expandable storage |
Many Canadian homeowners start with essential loads and expand later. Choose an inverter and battery that support adding capacity.
How a whole-home storage system works
- Solar panels (optional, but strongly recommended) produce DC power during the day.
- A hybrid inverter powers your home with solar first, charges the battery with any surplus, and draws from the grid when needed.
- The battery stores energy for evening use, for times when electricity costs more, or for outages.
- When the grid fails, the inverter isolates your home from the grid and keeps your backed-up circuits running from the battery and solar.
Without solar, a battery can still charge from the grid and act as a quiet, fuel-free backup supply. See our guide to home battery backup without solar.
How to size a whole-home system
Step 1: Peak power (kW). This sets the inverter size.
List the large loads that could run at the same time, such as the range, dryer, well pump, air conditioner or heat pump, and EV charger. Then add the base load. Motors draw several times their running current when they start, so check the inverter's surge rating as well as its continuous rating. If one inverter is not enough, some models can run in parallel.
Step 2: Daily energy (kWh). This sets the battery size.
Check your utility bill or online usage data for your average daily consumption. Then decide how much of that you want to cover, and for how long. Covering an overnight outage with the furnace fan, fridge, and lights takes far less storage than running electric heat through a two-day winter storm. Solar reduces the battery size you need on sunny days. Winter production in Canada is low, though, so size for the season you care about most.
Step 3: Electric heat changes everything
Baseboard heaters, electric furnaces, and heat pumps in cold weather can use more energy in one winter day than a battery bank can reasonably supply. For these homes, plan for backup heat from a gas furnace (with only its fan on battery), a wood stove, or a generator connection. Size the battery for everything else.
System types that can power a whole home
1. Low-voltage (48V) hybrid system: flexible and expandable
A split-phase hybrid inverter paired with 48V LiFePO4 batteries is the most common whole-home setup we supply.
- Inverter: the Growatt SPH 10000TL-HU-US for typical homes. For larger homes or bigger loads, consider the SPH 11.5 kW, SPH 15 kW, or SPH 18 kW. Those three models offer 200 A passthrough for whole-home connection, switch to backup in under 10 ms, and can run up to 6 units in parallel.
- Battery: the GSL 14.34 kWh 48V LiFePO4 wall-mount battery. It is UL9540 certified (DC), UL9540A tested, and rated for 8,500+ cycles, with a 10-year warranty. You can connect up to 16 in parallel. It is rated IP20 for indoor installation, and a self-heating version is available for colder spaces such as garages.
- Kit option: the Growatt SPH 10000 home backup system with 1 to 2 GSL batteries (14.34 to 28.68 kWh).
2. High-voltage grid-tie + battery system
A battery-ready grid-tie inverter with high-voltage batteries and a transfer switch is another route to whole-home backup. The Growatt 11.4 kW Whole Home Backup Power System pairs the MIN 11400TL-XH-US inverter with APX 5 kWh high-voltage LFP modules and a 200 A automatic transfer switch.
3. Off-grid systems
Homes and cottages with no grid connection use off-grid inverter/chargers and a larger battery bank, often with a generator for long cloudy stretches. See our off-grid inverters and our comparison of solar inverter types.
What to look for in a home battery
- Chemistry: LiFePO4 (LFP) is the standard for home storage because of its thermal stability and long cycle life.
- Safety certification: Look for UL9540 system listing and UL9540A test data. Inspectors and insurers increasingly ask for both.
- Usable capacity and expandability: Check usable kWh, not only nominal capacity, and how many units can be added later.
- Compatibility: The battery and inverter must communicate, typically over CAN or RS485. Use pairings that the manufacturers list as compatible.
- Cold-weather limits: Lithium batteries have minimum charging temperatures. In unheated spaces, choose a self-heating model or an indoor location.
- Warranty: Compare both the years covered and the cycle or energy throughput terms.
Ontario: rates and rebates
Ontario utilities offer Time-of-Use, Tiered, and Ultra-Low Overnight price plans. A battery can charge from solar, or from the grid during lower-priced hours, and supply your home during higher-priced hours. Compare your utility's current rates before you count on savings.
The provincial Home Renovation Savings Program lists a battery storage rebate of $300 per kWh, up to 50% of costs and a maximum of $5,000. The battery must be paired with a new solar PV system and sized to it, and you must give up net metering to receive the solar incentive. Standalone batteries and batteries added to existing solar do not qualify. Read the full details in our Ontario solar and battery rebate guide.
What about businesses?
Commercial sites use storage for backup and for peak shaving, which reduces demand charges, and they often need three-phase equipment. Read how commercial energy storage cuts costs and how commercial batteries support grid stability. For three-phase sites, see the Growatt WIT 28 to 55 kW commercial hybrid inverter.
Next steps
- Gather 12 months of electricity usage data and a list of the loads you need during an outage.
- Decide between essential-loads and whole-home backup.
- Choose an inverter for peak kW and a battery for the kWh you need, with room to expand.
- Work with a licensed electrician on permits, ESA inspection (in Ontario), and utility approval.
Browse home battery backup systems and home solar batteries, or read our home battery backup guide for Canada and Growatt 10 kW hybrid system guide. Questions? Contact the ROCKSOLAR team in Waterloo, Ontario for help sizing a system.