Batteries are the shiny add-on of the solar world. They are also one of the easiest places to overspend. Here is a grounded look at what they do, what they cost and when they earn their place, written for a Canadian household in late 2026.
What a battery actually does
A battery stores electricity from your panels, or cheap electricity from the grid, so you can use it later. That gives you up to three benefits. It provides backup power during an outage. It lets you use more of your own solar by shifting daytime power to the evening. And it can cut costs where electricity prices change by time of day. Not every home needs all three. Many need none.
Grid-tied solar without a battery
Most homes with panels stay connected to the grid and have no battery. Daytime surplus goes out to the grid, and you draw from it at night. Most provinces credit exports at or near retail rate with credits that roll over, often for 12 months, so the grid works as a free battery. Check the specifics in net metering across Canada.
Remember the safety rule: a basic grid-tied system switches off during a blackout (anti-islanding). Without a battery and a backup-capable inverter, panels will not keep your lights on, however sunny the outage.
When a battery may be worth it
- Frequent or long outages where you live, or someone at home depends on powered medical equipment
- Low payment for exported power, as in places with net-billing-style arrangements, so storing it and using it later beats selling it
- Time-of-use pricing with a big gap between peak and off-peak rates
- A wish for independence, understood as a lifestyle choice, not a financial one
It probably is not worth it if your utility offers generous credits, outages are rare and short, or your budget is tight and the money would do more elsewhere, for example on insulation or air sealing.
Sizing and specs in plain words
Capacity, in kWh, is how much energy the battery holds. Typical home units run from about 5 to 15 kWh. Power, in kW, is how much it can deliver at once, and a low figure may struggle with a well pump or an electric oven. Usable capacity and round-trip efficiency tell you how much you really get back, because some is always lost. Cycle life and warranty tell you how long it should last, and many carry warranties of around ten years. Lithium iron phosphate chemistry is common.
An average Canadian home uses roughly 9,000 to 12,000 kWh a year, which is about 25 to 33 kWh a day. Electrically heated homes use much more.
A worked example
Suppose an outage hits in January. You want the fridge (about 1 kWh a day), lights and internet (about 1 kWh), a furnace fan (about 1 to 2 kWh) and some phone charging. Call it 4 to 6 kWh over 24 hours. A 10 kWh battery would therefore cover those critical loads for a day or two, and longer if the panels can recharge it on a bright day. Add an electric range, a dryer or electric baseboard heat, and the same battery is flat in a few hours. That gap is why whole-home backup needs far more storage than most people expect. The battery sizing guide walks through the calculation with your own loads.
Backup the sensible way
Rather than trying to back up the whole house, many people pick a critical loads panel: fridge, lights, internet, a few outlets, maybe the furnace fan. It keeps the battery small and the price down. For long winter outages, some households compare a battery to a standby generator, and our piece on battery versus generator sets out runtime, noise, fuel and cold weather.
The cost reality
At the time of writing, batteries often add several thousand dollars to a quote, and up to well over ten thousand for larger units (CAD). Battery economics are weak where credits are generous and strong mainly for backup or time-of-use arbitrage. Provincial rebates for batteries were reported active in some provinces in 2026, but terms change, and the federal grant that used to help is closed. Verify what is available with the incentives checking guide before deciding. For price ranges and what drives them, see home battery cost in Canada.
Questions to ask before you buy
Ask what the battery does when the grid fails in winter, because cold garages can limit output and charging, and many units want a sheltered spot. Ask how many circuits it will actually carry, what the warranty says about remaining capacity after ten years, and who services it. Get the backup behaviour in writing, and check that the installer holds the right electrical licence and that the equipment carries a recognised certification mark such as CSA. Permits and an electrical inspection apply to storage as well as to panels.
A reasonable approach
Install solar first. Make sure the system is battery ready, meaning the inverter and wiring allow you to add storage later. Then revisit the question when your needs, prices or local rules change. You lose little by waiting.
For the bigger picture of where batteries sit in the finances, see what solar costs and how payback works. Backup and storage articles are gathered in the batteries and backup hub.
Quick answers
Do I need a battery with solar panels?
Not always. Where your utility credits exports well and outages are rare, a battery may not pay for itself.
Will panels work in a blackout without a battery?
No. Grid-tied systems shut down for safety unless paired with backup-capable equipment.