Path-Q Solar
How much additional solar generation is needed to recharge a battery after an outage?
Answer
The required solar energy is greater than the energy removed from the battery because charging and conversion are not lossless. A planning estimate is discharged usable energy divided by the combined charging and conversion efficiency, then adjusted for available sunlight, system limits, other household loads, battery reserve, and weather.
Key points
- Distinguish battery energy to be restored from solar energy required at the array.
- Account for household loads operating while the battery recharges.
- Check the maximum solar charging power accepted by the inverter and battery.
- Model the number of sunny and cloudy days relevant to the intended outage scenario.
What it depends on
- Energy removed during the outage
- Charging and conversion efficiency
- Solar array production under actual conditions
- Concurrent loads and battery charge limits
Risks and trade-offs
- A battery may not fully recharge in one day after a large or cloudy-weather outage.
- Oversizing solar for rare outages increases cost and may have limited everyday value.
- The battery may reserve capacity or restrict charging to protect its life.
Information you may need
- Battery usable capacity and outage discharge
- Solar array size and production model
- Charging limits and efficiency assumptions
- Expected weather and concurrent loads
Your next step
What to do next
Request a multi-day recharge simulation for the intended outage loads, including cloudy-day and concurrent-use assumptions.
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