Power Outage Load Planner
Build the outage around the loads you refuse to lose. The planner converts each device into daily watt-hours, then sizes storage for the outage window you choose.
| Load | Watts | Equivalent hours/day | Include | Wh/day |
|---|
Why equivalent hours are useful
Many outage loads do not run continuously. A refrigerator compressor may cycle for a fraction of the day, a sump pump may run only during water events, and a furnace blower turns on with heating calls. “Equivalent hours per day” converts those cycling loads into a simple energy budget while still letting you use the appliance’s running watts.
How recharge changes the storage requirement
For a short outage, stored energy may cover everything. Over 48–72 hours, even modest solar, vehicle or generator recharge can reduce how much battery must be purchased upfront. This planner subtracts the daily recharge you enter, but only count recharge you can realistically depend on. Solar production varies with weather, season, shading and panel placement.
Energy and power are separate constraints
The storage result is in watt-hours. You must separately verify that the inverter can supply the highest simultaneous running load and any motor/compressor startup surge. A battery can contain enough energy for three days and still be unable to start a well pump or furnace motor.
Use your own measurements
The preset values are starting assumptions, not appliance standards. Replace them with a plug-in energy meter, appliance label or manufacturer manual whenever possible. This matters most for refrigeration, heating equipment, pumps and aquariums because duty cycle can change substantially during extreme weather—the exact time backup power matters most.