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Case study·Leaside, Toronto·Tesla Certified Installer

Leaside House
Whole-home backup on the existing 200 A service

A 5,000+ sq ft Leaside home with a sauna, a heated pool, an EV, patio heaters and snow-melting walkways, and owners who wanted all of it to keep running through outages, with no generator. We sized the system on a year of the home's own hourly data, kept the 200 A service and backed up the whole house.

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Tesla Powerwall 3 and Expansion installed outside a Leaside home beside the meter and Gateway
Powerwall 3 and Expansion, Leaside
27 kWh
Stored energy: Powerwall 3 plus one Expansion
11.5 kW
Output: enough for the whole panel
200 A
Existing service kept, 49 A of margin
18 to 22 h
Backup living normally, about 40 h on essentials
Finished

Leaside House, Toronto

Main electrical panels before the Powerwall install, Leaside home, Toronto
aFinished panels with the Tesla Backup Gateway and new subpanel, Leaside home, Toronto
aTesla Powerwall 3 and Expansion installed outside a Leaside home, Toronto
The house

Nearly all-electric, and busy

This is a large family home, over 5,000 square feet, and almost everything in it runs on electricity. The gas furnace is the only gas heat left. Around it: an electric kitchen, two air conditioners, home offices, a sauna, a pool heated by a heat pump, an EV charger, electric patio heaters and heated mats that keep the walkways clear of snow.

The owners wanted all of it backed up, automatically, with no generator's fuel, noise or yearly service. And they did not want a bigger service unless the numbers said they needed one.

What they asked for

  • The whole house backed up, automatically
  • No generator
  • No service upgrade unless the numbers required it
  • Room to add solar later

Why a battery suits this house

  • Gas heat: in an outage the furnace only needs power for its fan
  • The biggest loads can be scheduled or paused
  • Time-of-use rates reward moving load to the night
  • Solar is planned, and the battery will store it
The systems

Six systems, one 200 A service

Each one is a serious load on its own. Here is roughly what each draws, when it runs, and how the house treats it when the grid is down. The bars compare each load with the battery's 11.5 kW output.

Sauna, Leaside HouseSauna

Electric sauna heater, 240 V

about 8 kW
When it runs
Evenings and weekends. Most of the energy goes into the first hour of heating up.
In an outage
Within the battery's output, but an hour of sauna uses about a third of the stored energy. A treat in an outage, not a habit.
EV charger, Leaside HouseEV charger

Tesla Wall Connector

about 10 kW while charging
When it runs
Overnight, on the cheapest time-of-use hours. One of the two biggest drivers of the home's peaks.
In an outage
Waits for the grid. A full charge would take most of the battery, and the car is already a battery.
Patio heaters

Bromic electric heaters

about 6 kW together
When it runs
Spring and fall evenings on the patio. Instant radiant heat, nothing to light.
In an outage
Left off. Nobody needs the patio warm during an outage.
Pool equipment

Heat-pump pool heater, pump and filtration

up to about 8 kW
When it runs
The pump runs daily; the heat pump through the swim season. It moves heat out of the air instead of making it, so it uses a fraction of a resistive heater's power.
In an outage
The pump can run. Heating waits for the grid.
Snow-melting mats

HeatTrak mats, plus roof heat trace

11.2 kW, all mats on
When it runs
During and after snowfall. Walkways from the front door to the sidewalk, side door and cars, and the driveway.
In an outage
Off on battery, from one switch on their own outdoor subpanel.
The rest of the house, Leaside HouseThe rest of the house

Kitchen, central air, laundry, offices, gas furnace fan

about 1.5 kW most of the time
When it runs
All day. Higher when the electric range, wall oven or the two air conditioners are running.
In an outage
Runs as normal. This is what the battery is there for.
On paper vs real life

More equipment than service, and it still fits

Add up every nameplate and this house looks like it needs a 400 A service. The meter tells a different story.

Everything switched on at onceThe equipment in the house, added up on paper
about 64 kW
Service limit, 48 kW
What the 200 A service can deliver200 A at 240 V
48 kW
The busiest real hour in 12 monthsEV charging and pool equipment together, April, midnight
23.7 kW
What the battery supplies on its ownPowerwall 3 output
11.5 kW
The big loads take turns. On paper this house has more equipment than its service can carry. In real life the car charges overnight, the sauna runs for an hour, the mats only run when it snows, and the busiest hour of the year used half the service. That gap is why measuring beats guessing.
How it comes together

The whole house, in one picture

We turned the original panel into a subpanel behind the Gateway, so every circuit is protected without moving a wire. The one load too big to carry on battery gets its own subpanel and a single switch. Tap Power out to see what changes.

Toronto Hydro supplies the house. The Powerwall charges, and runs the house through the expensive evening hours.

Toronto Hydro
Grid supply
Overhead service, 120/240 V
Service entrance
Meter and 200 A main breaker
New, certified for Canada. Sits ahead of the Gateway.
Tesla Gateway 3
Connected
Watches the grid every moment
Powerwall 3 + Expansion
27 kWh · 11.5 kW
Charging or shaving peaks
Home panel, every circuit backed up
The original 200 A panel, now behind the Gateway
No circuits moved, nothing left out. An energy monitor on the panel shows each load.
Kitchen and laundryNormal
Furnace fanNormal
Offices and internetNormal
Central airNormal
Pool pumpHeat pump too
SaunaNormal
EV chargerOvernight
Bromic heatersNormal
Snow-melt subpanel, one switch
All walkway mats on their own outdoor subpanel, fed from the home panel. Planned for this winter.
ON
RunningRunning, used lightlyWaits for the gridSwitched off
Why the Expansion

For a big house, hours matter more than power

A house this size idles at around 1.2 to 1.5 kW with nobody doing much: fridges, freezers, network, pumps, lights, the furnace fan. That baseline decides how long an outage the battery can cover.

One Powerwall 3

13.5 kWh stored

0 h12 h24 h
  • About 9 to 11 hours living normally in this house
  • An evening outage runs out before morning
  • Same 11.5 kW output
What we installed

Powerwall 3 + Expansion: 27 kWh

0 h12 h24 h
  • About 18 to 22 hours living normally: through the night and into the next day
  • Around 40 hours if the owners trim to essentials
  • More room to store solar once the panels go up
The Expansion adds energy, not power. Output stays at 11.5 kW either way, which already covers the house. What a large home runs short of in an outage is hours, so the second unit went where it pays off.
What we measured

A year of real data, not a guess

We pulled 12 months of the home's hourly use from Toronto Hydro, 8,760 hours, and lined the busiest hours up against the panel's energy monitor and the EV charger's own records, after checking the export for errors. Then we ran the Code calculation, including the snow-melting circuits being added.

Busiest hour in 12 months of hourly dataMeasured from the Toronto Hydro meter, 8,760 hours
98.8 A
Times 1.25, as the Code requiresOntario Electrical Safety Code load method for measured data
123.5 A
Plus the new snow-melting circuits22 added walkway mats, 6.6 kW, balanced across both legs
+ 27.5 A
Calculated loadWhat the service has to carry, by the Code method
151.0 A
Existing serviceKept as is
200.0 A
Result: no service upgrade. 151 A calculated against a 200 A service leaves 49 A of margin. We also told the owners plainly that this is the last addition of this size the service takes without another assessment.
How it responds

What the system does, moment by moment

Tap a situation to see the load and how long 27 kWh lasts.

The power goes out on a winter evening

Battery lasts18 to 22 h
Load: 1.2 to 1.5 kWLimit 11.5 kW

The Gateway disconnects from the grid and the Powerwall takes over in a fraction of a second. Lights, furnace fan, fridge, kitchen and offices carry on. Nobody touches a switch.

Stored energy is the limit, not output.

What we built

Everything on one wall, beside the meter

Equipment

  • Tesla Powerwall 3 with one Expansion: 27 kWh, 11.5 kW, mounted outside
  • Tesla Gateway 3 for automatic whole-home transfer
  • New 200 A meter and main breaker as the service entrance
  • Fused utility disconnect for the battery
  • Whole-home surge protector at the panel

Approvals and testing

  • Engineered single-line drawing and load assessment
  • Toronto Hydro interconnection application approved
  • Electrical Safety Authority inspection and Certificate of Acceptance
  • Outage test at commissioning, and handover in the Tesla app
Protecting the investment

A surge protector, because of what is plugged in

This house runs on electronics: a battery inverter, an EV charger, a pool heat pump, controls on the sauna and patio heaters. Electronics are what surges damage, so we added whole-home surge protection at the panel. It is a small part of the job that guards everything else.

Whole-home surge protector mounted beside the main panel
Whole-home surge protector, a Type 2 Eaton unit, mounted beside the panel and connected at the panel. It clamps a spike in microseconds and sends it to ground before it reaches anything plugged in or hard-wired.

Outside the house

Lightning and utility switching travel down overhead lines, and this house is fed overhead.

When the grid comes back

Power coming back after an outage can arrive with a spike as the lines re-energize.

Inside the house

Compressors and pumps switching on and off, from the air conditioners to the pool heat pump, create smaller spikes many times a day.

What it protects

Powerwall and GatewayEV chargerPool heat pumpSauna and heater controlsKitchen appliancesOffices and network
The process

How a project like this comes together

  1. 1
    Data review. Send the address. We pull a year of hourly use from the utility and see how the home actually runs.
  2. 2
    Load assessment and sizing. The Code calculation confirms the service, and the battery is sized to the home's real loads and the outage length that matters.
  3. 3
    Design and approvals. A single-line drawing, the utility interconnection application and the electrical permit.
  4. 4
    Install. The utility disconnects the service for the day, the equipment goes in, and power is back by the afternoon.
  5. 5
    Inspection, commissioning and handover. Electrical Safety Authority inspection, an outage test, and the owners set up in the Tesla app.
  6. 6
    Grow with the house. New loads get assessed against the same data, and solar connects straight to the Powerwall's built-in inputs.

Your home is different. Your data will show how.

Find out what your house needs before you buy

Send the address. We review your hourly data, size the backup to how your home actually runs, and send a fixed quote within 1 to 2 business days.

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Straight Answers

Leaside House Questions

The kind we would give before you commit a dollar of capital. Tap a question.

Did the house need a service upgrade for the Powerwall or the snow-melting mats?
No. A year of hourly meter data put the calculated load at 151 A on the existing 200 A service, 49 A of margin after adding the new snow-melting circuits. We put that in writing in an engineered load assessment.
Does the whole house run on the battery?
Yes, the whole panel. The original panel now sits behind the Gateway, so every circuit is backed up. The Powerwall 3 supplies up to 11.5 kW. The snow-melting mats are the one large load planned on their own subpanel with a single switch, so they can be turned off to stretch the battery.
Can a battery back up a house with a sauna, a pool and an EV?
Yes, if it is designed around how the house runs. The big loads rarely run together. The battery covers the house as it is lived in, the EV waits for the grid, pool heating pauses, and the snow-melting mats switch off. A year of meter data shows which loads actually overlap.
Does a large, mostly electric home need a 400 A service?
Not always. This 5,000+ sq ft home has more connected equipment than its 200 A service could carry at once, yet its busiest hour in a year used about half the service. A load assessment on a year of utility data, by the Code method, shows whether an upgrade is actually needed.
What does a Powerwall Expansion add?
Stored energy, not output. A Powerwall 3 holds 13.5 kWh and supplies up to 11.5 kW. Adding one Expansion doubles storage to 27 kWh with the same output, which is what stretches a large home through a full night of outage.
Why install a surge protector with a battery system?
To protect the electronics. Inverters, EV chargers and heat pump drives are sensitive to spikes from lightning, utility switching, grid restoration and motors starting inside the house. A Type 2 surge protector at the panel limits those spikes before they reach the equipment.
How long does it last in an outage?
It depends on what is running. With 27 kWh stored: about 18 to 22 hours living normally, and around 40 hours on the essentials only. With every snow-melting mat on, about 2.5 hours.
Why is it mounted outside?
It is rated for Toronto winters, it keeps the garage and basement free, and it is easier to service. The battery, Gateway and disconnects sit together on the brick wall beside the meter.
Can solar be added later?
Yes, and it is planned. The Powerwall 3 has solar inputs built in, so 12 kW of panels can connect directly with no separate inverter. The wiring installed in phase one already suits it.

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