Learn how home batteries, solar-plus-storage, generators and vehicle-to-home systems keep the lights on, and how to size and install them safely.
Ice storms, windstorms, wildfires and summer heat waves can all knock out power in Canada, sometimes for days. For households that depend on a sump pump, a well pump, medical equipment or electric heat, an outage is more than an inconvenience. At the same time, more homes are adding solar and electric vehicles, and many are wondering whether a battery belongs in the picture too.
This course explains how home batteries work and how they compare with other backup options, including generators and the growing ability of some EVs to power a home. You'll learn the key specifications, how to plan backup around the loads that truly matter, how batteries pair with solar, and what makes an installation safe in a Canadian climate.
Because batteries are a significant investment, we also look honestly at costs and value. Sundamentals is an independent non-profit, and we don't sell batteries or generators. This course is marked Intermediate because it builds on basic electricity concepts; our solar course is a helpful companion, but not required.
The course is free, self-paced and takes about 50 minutes. It has three modules with knowledge checks and a 10-question final exam. Score 80% or higher to download your PDF certificate of completion.
A home battery stores electricity so you can use it later. Most residential batteries today use lithium-ion chemistry, the same broad family used in laptops and electric vehicles, packaged with a battery management system, safety controls and an inverter that connects them to your home's wiring.
Homeowners usually buy batteries for one or more of three reasons. The first is backup power: keeping key circuits running when the grid goes down. The second is storing solar energy produced during the day for use in the evening. The third is shifting when you draw from the grid, charging the battery when electricity is cheap and using it when prices are higher, where your utility has time-of-use pricing.
Which of these goals matters most to you shapes everything else, from the size of the battery to how it is wired. A battery bought mainly for backup may sit nearly full most of the time, waiting for an outage. A battery bought to save money cycles every day. Many systems can be set to balance both, for example by keeping a reserve for outages while cycling the rest.
It is also worth being realistic about what a battery is not. In most of Canada, a typical home battery cannot run an entire home with electric heat for days in mid-winter. It is best thought of as a way to keep essential needs running and to make better use of your solar or cheaper electricity.
Battery specifications can be confusing, but a handful of numbers tell you most of what you need. Capacity, measured in kilowatt-hours (kWh), is how much energy the battery stores. Usable capacity is the portion you can actually draw on, since many batteries keep some charge in reserve to protect their lifespan. Always compare usable capacity between products.
Power, measured in kilowatts (kW), is how much electricity the battery can deliver at once. A battery with plenty of capacity but low power might run a fridge for a long time but struggle to start a well pump or central air conditioner at the same time as other loads. Some specifications list both a continuous power rating and a short-term peak or surge rating for starting motors.
Round-trip efficiency is the share of energy you get back out compared with what you put in. Lithium-ion home batteries are often around 90 percent efficient, meaning a small amount of energy is lost each time the battery charges and discharges. Warranties typically guarantee a minimum share of capacity after a set number of years or a set total amount of energy cycled through the battery, whichever comes first.
Chemistry matters too. Many home batteries now use lithium iron phosphate, or LFP, which is valued for long cycle life and good thermal stability. Others use nickel-based lithium chemistries that pack more energy into less space. Both can be safe when certified and installed properly.
The best way to plan backup power is to start with what you truly need during an outage, not with a product brochure. Make a list of essential loads and estimate how much power each needs and for how long. An electrician or installer can help measure loads and identify which circuits they are on.
Typical essentials in Canadian homes include the refrigerator and freezer, a sump pump, a well pump if you have one, the furnace fan or boiler controls, some lights, internet and phone charging, and any medical devices. Electric heating, electric water heaters, ovens, dryers and central air conditioning use far more power and can drain a battery quickly.
Many battery installations use an essential loads panel, a separate small panel that holds only the critical circuits. During an outage, the battery powers only that panel, which stretches your stored energy much further. Whole-home backup is possible, but usually requires larger or multiple batteries and careful load management, and even then you may need to limit heavy loads during an outage.
Think about the kind of outages you face. A few hours during a summer storm is very different from several days of an ice storm in January. If long winter outages are a real risk for you, consider whether your heating system can run on backup power, and whether you need more than a battery alone, such as solar recharging or a generator.
A standard grid-tied solar system shuts down during a power outage so it cannot send electricity into lines that utility crews may be repairing. That surprises many solar owners the first time the power goes out on a sunny day. To use your solar during an outage, you need a battery or other equipment that can safely disconnect your home from the grid, a process called islanding, and keep running.
That disconnection is handled by an automatic transfer switch or a gateway device. When the grid goes down, it isolates your home, and the battery and inverter create a stable local supply. Your solar panels can then keep producing and recharge the battery during daylight, potentially extending your backup through a multi-day outage if the weather cooperates.
There are two main ways to connect a battery to solar. In an AC-coupled system, the battery has its own inverter and connects to your home's AC wiring, which makes it a common choice for adding storage to an existing solar system. In a DC-coupled system, panels and battery share a single hybrid inverter, which can be slightly more efficient and is often chosen for new installations.
Remember that winter solar production in Canada is limited by short days and snow, so in a January outage your panels may provide only modest recharging. Plan your backup capacity with that in mind.
If you already have solar and are thinking of adding a battery later, check with your installer about compatibility before you commit. Some inverters and monitoring systems work best with specific battery brands, and adding storage may require updates to your utility connection agreement. Planning for storage when you first install solar, even if you buy the battery later, can save money and hassle.
Generators remain the most common backup option in Canada. Portable generators are relatively inexpensive and can run selected appliances through extension cords or, more safely, through a properly installed transfer switch or interlock. Permanently installed standby generators run on natural gas or propane and can start automatically, often powering much or all of a home for as long as fuel is available.
Generators have trade-offs: noise, fuel storage, regular maintenance and exhaust. Carbon monoxide from generators is a serious and sometimes fatal hazard. Never run a generator indoors, in a garage, or near windows, doors or vents, and make sure you have working carbon monoxide alarms. Never connect a generator by plugging it into a household outlet, which can send power back into the grid and endanger line workers.
A newer option is using your electric vehicle as a backup battery. Some EVs offer vehicle-to-load, letting you plug appliances directly into outlets on the car. A smaller number support vehicle-to-home, where compatible bidirectional chargers and transfer equipment let the car power your home's circuits. An EV battery is often much larger than a typical home battery, so this can be a powerful option.
Vehicle-to-home requires specific vehicles, chargers and installation, and it may affect how you use the car during an outage. Check the vehicle manufacturer's guidance and warranty terms. For many homes, a combination of tools, such as a small battery for short outages and a generator for long ones, offers a sensible balance.
Whichever option you choose, test your backup before you need it. Run your generator or battery system periodically, check fuel supplies and expiry dates, and make sure everyone in the household knows how to operate it safely. An outage in the middle of a winter night is not the time to read the manual for the first time.
A home battery is a major electrical installation and must be done by qualified professionals with the required electrical permit and inspection. Batteries and inverters must carry recognized certification marks for use in Canada, and installations must follow the electrical code and local fire and building rules, which can restrict where batteries are placed and how many can be grouped together.
Location matters. Batteries are commonly installed in garages, utility rooms, or outdoors in weather-rated enclosures. Installers consider clearances, ventilation, protection from vehicle impact and access for firefighters. Some locations, such as bedrooms and certain living spaces, are typically not permitted.
Temperature is a particular concern in Canada. Lithium-ion batteries generally should not be charged when the cells are below freezing unless the system has built-in heating, and performance drops in extreme cold or heat. If you plan an outdoor or unheated garage installation, ask how the product manages cold, what its operating temperature range is, and whether it heats itself.
Finally, tell your home insurance provider about the installation, keep permit and inspection documents, and register the product for warranty. Ask the installer to show you how to check the system's status and what to do if it shows a fault.
Lithium-ion battery fires are rare, but they can be intense and hard to extinguish, which is why certification and code-compliant placement matter so much. Avoid uncertified products sold online and do-it-yourself battery builds. A properly certified system, installed by qualified professionals in an approved location with working smoke alarms nearby, keeps the risk very low.
Home batteries remain a significant investment. The cost depends on capacity, power, brand, whether you need an essential loads panel or electrical upgrades, and installation complexity. Get several quotes and compare them on usable capacity, power ratings, warranty terms and what is included.
Measuring value depends on your goal. For backup, the value is peace of mind and avoided losses, such as a flooded basement or spoiled food, which is personal and hard to put a number on. For savings, value depends on the difference between your utility's high and low electricity prices and on how your net metering program credits exported solar. In many Canadian markets, bill savings alone may not pay back the full cost of a battery, so be cautious with sales projections that suggest otherwise.
Some utilities are experimenting with programs that pay or credit homeowners for letting the utility draw on their batteries during periods of peak demand. These are sometimes called virtual power plants, because many small batteries together act like one larger power source. Such programs can improve the economics, but terms vary and can change.
Incentives for batteries are limited and change over time. Check the Sundamentals rebate finder for any current provincial, municipal or utility programs where you live, and confirm details directly with the program before you buy.
When you get quotes, ask the installer to show their assumptions in writing: how many outages they expect you to cover, how many hours of backup the system will give your essential loads, and any bill savings they project. Comparing those assumptions side by side helps you see which proposal actually matches your goals and which one is relying on optimistic numbers to look attractive.
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