Home battery backup critical-loads checklist

Battery backup planning begins by deciding what must stay on during an outage. Whole-home backup and critical-load backup are different projects.

Use this guide before selecting a home battery so critical loads, runtime, inverter output, transfer/islanding, location, and solar or generator interaction are understood.

When to use this guide

• A homeowner wants to keep essentials running during outages without assuming whole-home backup.
• A solar quote includes battery-ready or battery backup language that needs an electrical scope review.
• A generator, critical-load panel, transfer switch, or utility-interactive system could interact with the battery.

Inputs to gather

• Critical-load list split into must-run, nice-to-have, and exclude-during-outage loads.
• Running watts or amps, starting loads, duty cycle, outage duration, and seasonal or cold-weather assumptions.
• Battery kWh, usable reserve, inverter continuous and surge output, battery chemistry, indoor/outdoor rating, and product markings.
• Backup architecture: critical-load panel, whole-home backup, PV-assisted backup, generator-assisted backup, or non-backup storage.
• Transfer equipment, islanding method, utility requirements, location, ventilation/clearance, labeling, and maintenance instructions.

Project path matrix

Working checklist

• Confirm the project branch: A homeowner wants to keep essentials running during outages without assuming whole-home backup.
• Measure or photograph the first hard inputs: Critical-load list split into must-run, nice-to-have, and exclude-during-outage loads. Running watts or amps, starting loads, duty cycle, outage duration, and seasonal or cold-weather assumptions.
• Record the decision basis: A battery with enough kWh can still fail to start or carry a high-surge load. Use ESS product listings, manufacturer instructions, utility interconnection requirements, and local authority review.
• Keep the handoff package together: Critical-load worksheet with must-run and excluded loads.
• Stop before work proceeds if this applies: The battery supports medical, life-safety, sump pump, refrigeration, heating, or business-critical loads.

Workflow

1. Define the outage job before choosing battery size: what must run, for how long, and what can stay off.
2. Separate energy capacity in kWh from inverter output and starting-load capability.
3. Compare backup architecture options before assuming whole-home backup.
4. Check product location, environmental, clearance, transfer, and utility requirements before equipment selection.
5. Document interaction with solar, generator, EV charging, heat pumps, sump pumps, and critical medical or communications loads.

Decision checkpoints

• A battery with enough kWh can still fail to start or carry a high-surge load.
• Critical-load panels often make runtime and inverter sizing more practical than whole-home backup.
• Solar does not automatically power the house during outages unless the inverter, battery, transfer, and utility requirements support that mode.
• Generator and battery interaction needs deliberate transfer and control review.

Canada-specific checks

• Use ESS product listings, manufacturer instructions, utility interconnection requirements, and local authority review.
• Cold-weather performance, indoor/outdoor location, and ventilation/clearance assumptions can matter in Canadian installations.
• Do not claim a battery is sufficient, acceptable, or approved from this checklist.

Project package to keep

• Critical-load worksheet with must-run and excluded loads.
• Battery and inverter data sheets, product markings, location plan, transfer equipment details, and utility requirements.
• Runtime, load-list, and battery conversion calculator outputs.
• Solar, generator, or transfer-switch documents if systems interact.

Stop and get local review

• The battery supports medical, life-safety, sump pump, refrigeration, heating, or business-critical loads.
• The system interacts with solar export, generator backup, EV charging, or whole-home transfer.
• Location, ventilation, clearance, product listing, or utility/islanding requirements are unclear.

Questions to settle before work starts

• Which local authority, utility, property authority, product listing, or manufacturer instruction controls this solar pv and storage decision?
• Which inputs are measured from the field or nameplate, and which are still assumptions from a quote, drawing, or memory?
• Which part of the work will be concealed, energized, interconnected, or purchased before review if the sequence is not controlled?
• Which single assumption would change the equipment choice, installation path, cost, schedule, or inspection timing?
• Who will keep the final photos, calculator outputs, product documents, permit or utility records, and commissioning notes?

Use the related tools

• Use the Load List kVA and Amps Calculator to build the critical-load list.
• Use the Battery Runtime Calculator for preliminary duration screening.
• Use the Battery Ah and kWh Calculator when product data uses different battery units.

Public reference starting points

• BC Hydro battery storage - Utility battery-storage context.
• ESA energy storage systems podcast page - Authority discussion context for ESS boundaries.

Local standards and authority note

Confirm ESS location, product listing, transfer equipment, utility rules, and inspection requirements with qualified professionals.