Whole-Home vs Essential Loads Battery Backup in Toronto

# Whole-Home vs Essential Loads Battery Backup in Toronto

After "which battery brand," the second-biggest sizing decision in a home battery project is what does the battery actually back up? Whole-home backup runs every circuit during an outage — fancy, but expensive and sometimes unnecessary. Essential-loads backup runs only the critical stuff — cheaper, more efficient, more outage runtime per dollar.

This is the trade-off framework we walk every Toronto customer through. For the broader battery context, read [Home Battery & Powerwall Toronto Complete Guide](/blog/home-battery-powerwall-toronto-2026-complete-guide). For the brand-by-brand version, see [Tesla vs FranklinWH vs Enphase](/blog/tesla-powerwall-vs-franklinwh-vs-enphase).

The Three Backup Architectures

1. Essential Loads (Critical Loads Sub-Panel)

A separate small sub-panel is installed downstream of the gateway. Only the circuits you really need during an outage are moved to that sub-panel: fridge, furnace fan, microwave, internet/router, sump pump, a few outlets, sometimes a small AC window unit.

• Battery sized to: critical load demand (typically 4-6 kW peak, 5-10 kWh/day)
• Cost: lowest — single Powerwall 3 with small sub-panel
• Outage runtime: 24-48 hours typical
• Complexity: simple

2. Whole-Home with Smart Load Management

The entire main panel sits behind the gateway. A smart load controller (Tesla Gateway 3, FranklinWH aGate, Span Panel, Enphase IQ System Controller) dynamically sheds non-essential loads when it detects high demand exceeding the battery's continuous output.

• Battery sized to: average load with smart shedding (typically 1x Powerwall 3 or 1x FranklinWH)
• Cost: medium — battery + smart panel ($1,800-$3,500 extra)
• Outage runtime: depends on what runs; 12-30 hours typical
• Complexity: medium

3. Whole-Home Without Load Management

Battery sized large enough to handle full house peak load, no smart shedding. Brute-force approach.

• Battery sized to: full peak load (often 2x Powerwall 3 = 23 kW continuous)
• Cost: highest — multiple batteries
• Outage runtime: 12-20 hours running normally
• Complexity: simple wiring, expensive hardware

Real Toronto Load Profiles

To pick the right approach, we measure your actual usage with your Toronto Hydro hourly data.

A typical Toronto household at idle (everyone home, doing normal things, no AC or heat pump): 0.6-1.2 kW continuous.

A Toronto household with central AC running on a hot day: 3-5 kW continuous.

A Toronto household with everything going (AC + range + dryer + EV charging): 15-22 kW peak.

Essential Loads: What We Recommend Including

For most Toronto homes, the essential-loads list is:

Always:

• Fridge + freezer (food spoilage)
• Furnace fan + ignition (heat in winter)
• Sump pump (basement flooding risk)
• Internet/router (work from home, info during outage)
• A few key outlets (phone charging, lamps)
• Garage door opener (if attached garage is your only access)

Often:

• Microwave (cooking without a range)
• Bathroom outlet (hair dryer, shaver)
• Single small AC window unit (one room of comfort in summer)
• Medical equipment (CPAP, oxygen, etc.)

Rarely on essentials:

• Central AC (too much load)
• Electric range or oven (use propane camp stove or gas)
• Clothes dryer (skip a load)
• Hot water tank (use stored hot water for a day)
• EV charger (drive somewhere with power)

This list typically requires 3-5 kW continuous, which a single Powerwall 3 (11.5 kW continuous) handles comfortably with substantial headroom for surges.

Whole-Home with Smart Load Management

The smart-panel approach has matured significantly. The three options we install:

Tesla Gateway 3 with Load Management

Tesla's Gateway 3 (included with Powerwall 3) supports up to 4 controllable circuits through Tesla's load management. Limited but works for most homes. You designate AC, EV charger, and dryer as "shed during high demand" and the system manages them automatically.

• Cost: included with Powerwall 3
• Pros: Simple, integrated, Tesla app
• Cons: Only 4 circuits, less granular than aGate or Span

FranklinWH aGate (included with aPower 2)

Smart panel up to 12 controllable circuits, comes standard with FranklinWH. Ranks circuits by priority and sheds in order during high demand.

• Cost: included with FranklinWH
• Pros: Most circuits, best ranking logic, included
• Cons: Requires FranklinWH ecosystem

Span Panel (third-party, works with any battery)

Dedicated smart panel that replaces your main panel. Per-circuit control of every breaker.

• Cost: $4,500-$6,500 installed
• Pros: Most granular, brand-agnostic
• Cons: Most expensive, more complex install

Enphase IQ System Controller

Up to 4 controllable loads via separate IQ Load Controllers. Less integrated than aGate.

• Cost: included plus per-controller cost
• Pros: Modular like Enphase ecosystem
• Cons: More devices to commission

Sizing for Whole-Home Without Smart Management

Brute-force whole-home backup means sizing to your actual peak. For a Toronto home with central AC, gas heat, electric range:

• Peak load: ~12-15 kW (AC + range + microwave + lights)
• Battery requirement: at least 12 kW continuous

This means 2x Powerwall 3 ($26,500) or 1x FranklinWH aPower 2 ($13,500). FranklinWH's 12 kW continuous on a single unit is the most cost-effective whole-home option for medium-load Toronto homes.

For a fully electrified home (heat pump + EV + induction range + AC):

• Peak load: ~18-25 kW
• Battery requirement: 2x Powerwall 3 with smart shedding, or 2x FranklinWH

Cost Comparison Across Architectures

For a typical Toronto detached, 3,000 sq ft, central AC, gas furnace:

For most Toronto homes, the FranklinWH + aGate or Powerwall 3 + Tesla load management is the cost-effective whole-home choice.

Outage Runtime Comparison

For 13.5 kWh stored battery capacity:

Essential loads (3 kW average draw):

• 13.5 kWh ÷ 3 kW = 4.5 hours at peak draw
• More realistically with cycling loads: 20-36 hours

Whole-home with smart shedding (4 kW average after shed):

• 13.5 kWh ÷ 4 kW = 3.4 hours at full draw
• More realistically: 14-24 hours

Whole-home brute force, no shedding (8 kW average with everything running):

• 13.5 kWh ÷ 8 kW = 1.7 hours
• This is why brute-force needs 2 batteries

The math says: for maximum outage runtime per dollar, essential-loads wins. For convenience during short outages (under 12 hours), whole-home is fine. For multi-day outages, only solar pairing (see [Powerwall with Solar Toronto](/blog/powerwall-with-solar-panels-toronto)) provides indefinite runtime.

What We Recommend by Customer Type

Permit and Code

Both architectures fall under CEC Section 64-200 for energy storage and Section 26 for installation of electrical equipment. The smart panel adds Section 8 load calculations review by the inspector. Permit fees and process are identical — see [Home Battery Permit & ESA Toronto](/blog/home-battery-permit-esa-toronto).

Book a Load Audit

Before recommending whole-home or essential-loads, we pull your last 12 months of Toronto Hydro hourly data and model the architectures against your actual usage. Book a [home battery consultation](/services/hvac-energy/home-battery-powerwall) and we will show you the runtime curves for each option, with itemized costs and trade-offs.