Path-Q Solar
What battery capacity would be needed for overnight backup during a grid outage?
Answer
Estimate the energy required by the loads you want to run from the evening through morning, then add allowances for inverter losses, reserve capacity, battery operating limits, and uncertainty. The required battery size is not determined by house size alone; it depends on the selected loads and their duration.
Key points
- Calculate each load’s average power multiplied by the hours it operates.
- Include refrigerator cycling, lighting, communications, medical equipment, pumps, and heating controls as applicable.
- Check both total usable energy and the battery’s maximum continuous and surge power.
- Decide whether solar recharge, load shedding, or a generator is part of the plan.
What it depends on
- Overnight load list and operating schedule
- Battery usable capacity and reserve settings
- Inverter power and surge capability
- Expected temperature and recharge conditions
Risks and trade-offs
- Sizing for every possible load can make the battery costly and underused.
- Undersizing can cause shutdowns before morning.
- A battery with enough energy may still lack the power to start or run a large appliance.
Information you may need
- Measured overnight energy use
- Critical-load priorities
- Battery usable kWh and power specifications
- Desired reserve and no-recharge assumptions
Your next step
What to do next
Prepare an overnight load schedule and request quotes showing usable capacity, power capability, reserve, and expected morning state of charge.
Path-Q
Find the right next step
Answer a few questions and we’ll narrow your options.
Loading…
SQ00354