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Critical Load Analysis

Required capacity

1334Wh

That's roughly 1334 Wh of stored energy — about 1 hours of a typical home's power.

1,215 W total · 2× 100Ah 12V batteries · 20% buffer

Total load1,215W
Estimated total surge4,500W
Required capacity1,334Wh
Battery bank2× 100Ah 12V batteries
Inverter efficiency92%
Avg hourly use139Wh/hr
Daily energy3,335Wh/day

High surge load detected. Check if your inverter can handle this peak: Inverter Peak Load Surge

Note: Required Wh = average hourly consumption × backup target hours × 1.2 safety factor. Estimated surge uses running watts × 5 for high-surge devices. Battery count assumes 12 V 100 Ah cells at 80% depth of discharge and 92% inverter efficiency.

Plan essential loads, not the whole house

During an outage, size for circuits you truly need—fridge, lights, internet, and a few outlets—not every HVAC zone or dryer. This tool turns that appliance list into Wh capacity and a starter battery count.

Home Backup Battery Sizing — bank Ah & runtime

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How this calculator works

How to use the Critical Load Analysis

The Formula

List each essential appliance with running watts and hours used per day. We average daily consumption into an hourly Wh rate, multiply by your target outage duration, and add a 20% safety buffer for inverter loss and aging.

Practical Example

The 12 V 100 Ah count is a planning shortcut—nominal 1,200 Wh per battery with 80% depth of discharge and 92% inverter efficiency. Pair with Home Backup Battery Sizing for voltage, DoD, and bank Ah.

About Critical Load Analysis

How critical load analysis works

List each essential appliance with running watts and hours used per day. We average daily consumption into an hourly Wh rate, multiply by your target outage duration, and add a 20% safety buffer for inverter loss and aging.

Battery bank suggestion

The 12 V 100 Ah count is a planning shortcut—nominal 1,200 Wh per battery with 80% depth of discharge and 92% inverter efficiency. Pair with Home Backup Battery Sizing for voltage, DoD, and bank Ah.

Frequently asked questions

Q: Peak vs. average load? A: Total running watts shows simultaneous demand; Wh capacity uses your daily usage pattern. Q: Include surge? A: Use Inverter Peak Load Surge for motor start sizing. Q: Whole house? A: List only circuits you need during an outage.

Further Reading

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