How to Plan Home Backup Power Before the Grid Goes Down
Freezing rain coats the pines along the shore. By midnight, every window across the bay has gone dark. In one house, the floors stay warm and the taps still run.
That house didn’t get lucky. The family planned for it at the design stage.
This guide walks through how to size a backup system, which pieces it needs, and when to plan it. It also explains why keeping the hydro connection usually beats cutting it.
Key Takeaways
- Restoration order: Utilities repair the lines that serve the most customers first. Cottages at the end of long rural lines can stay dark for days after the nearest town has power again.
- Target: Federal guidance asks every household to be ready to look after itself for at least 72 hours. That’s the starting point for sizing home backup power.
- Solar: Standard grid-tied solar systems shut off when the grid goes down. Short, snowy winter days also limit what solar delivers, so most families keep their hydro connection.
- Battery and generator: Batteries kick in as soon as the grid fails and run the essentials for hours. Standby generators carry the house through an outage that lasts days.
- Timing: Backup power costs least when it’s planned into the construction drawings. Generator pads, fuel lines, and battery rooms fit more easily into drawings than into finished walls.
Why Does Cottage Country Lose Power for So Long?
Cottage Country stays dark longer for two reasons. Its power lines run through heavy forest, and utilities repair the lines that serve the most customers first. Cottages at the end of long rural roads sit near the back of that line.
Trees Bring the Lines Down
Much of Cottage Country is heavily wooded. Ice, heavy snow, and high winds load the branches over the lines until limbs or whole trees come down. After a December 2022 storm, Huntsville’s mayor called snow-heavy canopies and high winds “a real recipe for causing serious hydro problems.”
The last two years show how often it happens.
Crews Fix the Biggest Lines First
Hydro One restores power by the rule “do the greatest good for the greatest number.” Its crews repair large lines that serve many customers before they move to lines serving a single home or a short road. Fallen trees and blocked roads slow them further.
During the 2025 ice storm, the Township of Muskoka Lakes was still pressing Hydro One to clear blocked roads days later, and its firefighters checked on residents who had been without power for more than 48 hours.
Empty Cottages Take the Damage
Nearly a week after the ice storm, 37,000 of the homes still without power were seasonal. In a house nobody is watching, the risk shifts from discomfort to damage. Federal guidance warns that extended outages can freeze water pipes. In a closed cottage, a frozen pipe can mean a flooded floor that nobody finds until spring.
Why Is Home Backup Power Worth the Investment?
In Cottage Country, home backup power protects the house as much as the family. Long outages can freeze the pipes in an empty cottage, strand a family behind a closed road, and silence the alerts that tell an owner something is wrong.
The Insurance Gap in a Vacant Cottage
Outages get most expensive in an empty cottage. The Insurance Bureau of Canada says standard policies cover damage from burst pipes when the pipes sit in the heated part of the home. It also warns that most policies exclude frozen-pipe damage when a home is vacant, even with permission for the vacancy.
Custom cottages that keep its heat through an outage keeps its pipes above freezing. Before counting on that, ask your insurer how its policy treats a seasonal cottage, since rules on vacancy and regular checks vary.
Staying Put When the Roads Close
During the December 2024 snow squalls, part of Highway 11 stayed closed for nearly three days, and Gravenhurst stayed under a state of emergency for more than two weeks. In a storm like that, driving out can be riskier than staying. With heat, water, and light, the family can wait it out at home.
Freeze Alerts That Keep Reporting
Freeze and leak alerts only work while the cottage has power and a connection. Put the modem, router, and sensors on the must-run list, and the alerts keep reporting as long as the internet service itself stays up.
How Do You Size Backup Power for a Home?
Home backup power gets sized from two decisions. The first is how many days the house should run on its own. The second is which loads have to keep running.
Set the Number of Days
Seventy-two hours is the floor, since federal guidance asks every household to be ready to look after itself for that long. Full-time homes may need more, and so may cottages left closed for weeks in winter. The 2025 ice storm shows why. About 70,000 customers were still waiting for power nearly a week later.
Europe now uses the same baseline. On November 3, 2026, the European Commission set 72 hours of household self-sufficiency as a minimum, as national campaigns there prepare families for outages, cyberattacks, and sabotage.
List What Has to Keep Running
The must-run list sets the size of every system after it. Most lists start with these loads.
- Heat: The boiler, furnace, or heat pump, plus the pumps and fans that move the heat
- Water: The well pump, the pressure tank, and any water treatment
- Food: The fridge and freezer
- Connection: The modem, router, and phone chargers
- Health: Medical devices and any medication that needs a fridge
Water deserves extra attention. Drilled wells depend on an electric pump, so the taps stop when the power does. Ontario’s outage guidance tells homes on a well to power the pump with a backup generator. For cottages left empty in winter, our guide on how to winterize a cottage covers draining the lines as a second layer of protection.
Everything else, from the sauna to the wine wall, can wait for the grid.
Give the Must-Run Circuits Their Own Panel
From that list, the electrician totals the loads to size the battery and the generator. The must-run circuits then move to their own panel, often called a critical loads panel, which the backup system feeds. That lets a modest battery carry the heat and water without trying to run the whole house.
Why Does an Efficient Home Need Less Backup Power?
Custom homes that lose heat slowly need a smaller battery and generator, since every backup system has to replace the heat the house loses. It also burns less fuel through a long outage. Once the power fails, it cools more slowly, which buys time before the pipes are at risk.
Passive Survivability
Designers call this quality passive survivability. Alex Wilson of the Resilient Design Institute describes it as designing homes that stay habitable when they lose power. One architect quoted in ARCHITECT magazine gives a simple test. In a winter outage, the house should stay warm enough to live in for several days, with no frozen pipes.
How Gilbert + Burke Tightens the Shell
Every home we build is ENERGY STAR certified. Natural Resources Canada says a certified home is on average 20% more energy efficient than a typical new home. We set each home’s energy targets while we prepare the construction drawings. That’s the cheapest moment to tighten the shell, since nothing is built yet.
The window walls facing the lake get the closest look, because glass loses heat faster than an insulated wall. We place and size them so the view and the heating load both work. See how we approach custom home design.
Do Solar Panels Work During a Power Outage?
Not on their own. Standard grid-tied solar systems shut off during a grid outage. Hydro One’s connection rules require a home system to stop energizing its lines within two seconds of an outage. BC Hydro explains that the shutoff keeps power from flowing back into the grid while crews restore service.
What Solar Needs to Run in an Outage
To keep solar useful in an outage, the system needs a backup gateway that separates the house from the grid. It also needs a battery to store power for nights and cloudy days. With solar battery backup, the panels can recharge the battery during an outage when conditions allow.
Why Winter Favours Keeping the Hydro Connection
Winter limits what solar can deliver. December days are short, and snow can cover the panels. Natural Resources Canada notes that its monthly solar estimates don’t account for snowfall.
That’s why we suggest most families keep their hydro connection. Under Ontario’s net metering rules, extra solar power earns bill credits that carry forward for up to 12 months. Summer’s surplus then offsets winter bills, and the grid stays in place as the everyday backup.
Some families want no grid connection at all, and some lots have none. Our guide to building a luxury off-grid home covers that path.
How Long Can a Home Battery Carry a House?
Home battery backup carry the must-run loads for hours. Hydro One’s reliability program installed two home batteries holding 27 kWh in neighbourhoods with high annual outage hours. Hydro One says the system provides 10 to 40 hours of backup, depending on household use, and calls that range “not a guarantee.”
The low end of that range is a quarter of the high end. The gap comes from what the house asks the battery to run, which is why the must-run list matters as much as the battery’s size.
The real strength of a battery is the handoff. It takes over the moment the grid fails, with no engine noise and no fuel.
Forty hours won’t carry a house through a week-long ice storm. For longer outages, designers often add a generator so the battery doesn’t have to be oversized.
When Does a Home Need a Standby Generator?
Once an outage outlasts the battery, a standby generator earns its place. It carries the house through the long stretch of a multi-day storm.
Size the Fuel Tank for a Long Storm
On a propane generator, the tank size sets how many days it can run. Size it to outlast a storm that also blocks the road, since a delivery truck faces the same fallen trees as the line crews.
Real run time usually lands between the two ends, since a furnace, well pump, and fridge cycle on and off. Starting with a half-full tank gives half the days, so book a fill before storm season.
Permits and Inspections
Ontario’s Electrical Safety Authority says a standby generator permanently connected to a home must have a transfer device, which keeps its power from flowing back into the utility system. Connecting a generator permanently also requires a notification of work with the ESA. When a family asks for backup power, we plan the generator pad, fuel line, and transfer equipment into the drawings.
What Drives the Cost
Backup power adds cost. Covering every circuit with a whole-home generator or battery costs the most. Sizing the system to the must-run list keeps the cost in line with what the family needs.
What Heat Works With No Power at All?
Wood-burning fireplaces and stoves can heat a room with the power off. Federal guidance suggests non-electric heat as a backup and recommends cleaning a wood-burning chimney every fall. It also calls for working carbon monoxide alarms with battery backup.
Fireplaces already anchor the gathering rooms in most of our homes. Making at least one of them wood-burning adds a heat source that needs no power and no fuel delivery.
Will a Smart Home Work When the Internet Is Down?
Only the systems built to work offline will. The Cyber Centre notes that home thermostats and security systems now connect to the internet, and many aren’t as secure as they could be. Hydro One’s battery program, for example, requires a stable internet connection around the clock.
Lock Down the Smart Devices
Security matters too. The federal Get Cyber Safe program warns that a hacked smart device can give an attacker access to the home’s Wi-Fi. Its advice for smart homes comes down to a few habits.
- Separate network: Smart devices on their own network, apart from phones and laptops
- New passwords: Every default username and password changed
- Updates: Automatic updates turned on
In its guidance on voice assistants, the Cyber Centre also favours local data storage over the cloud and advises switching off remote access that isn’t needed.
Ask the Installer Before It Goes In
The same thinking applies to backup power. Before installation, ask these questions to the installer.
- Does the battery switch over when the internet is down?
- Does the generator start without an app?
- Can the family run the heat and the door locks from the wall when the network fails?
When Should Home Backup Power Be Planned?
Plan it at the design stage, before the construction drawings are final. Drawing in a generator pad, fuel line, and battery room is far easier than cutting them into finished walls.
When a family asks for backup power, we design it into the construction drawings alongside the home’s energy targets. That work happens during our Project Development Agreement stage, which typically runs two to four months. Our guide to the custom home building timeline shows where that stage falls.
Five Questions for Your Custom Builder
Builders who have planned backup power before can answer each of these.
- How many days will the house run without the grid?
- Which circuits stay on, and which wait for the grid?
- Where do the battery, generator, and fuel tank go?
- Who files the ESA notification and books the inspections?
- Will the systems run with the internet down?
If backup power is on your list, bring it to the first conversation. We’ll help you set the target and plan the systems that meet it.
FAQ: What Else Do Families Ask About Backup Power?
Can a generator connect to a house without a transfer switch?
Not safely. Federal guidance says a backup generator may connect to a home’s electrical system only through an approved transfer panel and switch, installed by a qualified electrician. It also warns against plugging a generator into a wall outlet.
Can a generator run in a garage?
No, according to Ontario’s Electrical Safety Authority. It warns against running a generator inside a home or garage, since the fumes build up to fatal levels. The ESA adds that fans and open doors won’t bring in enough fresh air. Federal guidance says to run a portable generator at least 6 metres (20 feet) from any home or building, with the exhaust pointed away from windows and doors.
Will a gas fireplace work in a power outage?
Federal guidance says a natural gas fireplace can provide warmth until the power is back on. How it lights matters, since some models need household power or a battery to start. Ask the installer how the fireplace starts in an outage, and test it before winter.
Can you flush a toilet during a power outage?
Yes, with stored water. Ontario’s outage guidance suggests filling the bathtub, if possible, and using that water to flush the toilet. If the well pump runs on backup power, the toilets keep working as usual.
