How Long Will My Battery Last?
This depends on three main factors:
- Your battery size (kWh capacity)
- Your backup reserve setting
- What loads are running in your home
The Biggest Factor: What You're Running
The single biggest factor is whether you're running:
- ❌ Air conditioning
- ❌ Electric heat
These are high-draw appliances that can drain a battery in a matter of hours.
Much less demanding:
- ✅ Lights
- ✅ Refrigerator
- ✅ Router
- ✅ Phone chargers
These can stretch a battery through a full day or more, especially with solar recharging during daylight.
Check Your Estimated Duration
Your app shows an estimated backup duration based on your home's usage history.
Where to Find It
| System | Location in App |
|---|---|
| Enphase | Battery > Backup Duration |
| Tesla | Powerwall > Backup |
Check This in Advance
💡 Check this before an outage occurs — not during one — so you have realistic expectations.
Quick Reference
| Usage Level | Approximate Duration | Examples |
|---|---|---|
| Essentials only | 12-24+ hours | Lights, fridge, router, phones |
| Moderate use | 6-12 hours | Add TV, some outlets |
| Heavy use | 2-6 hours | AC, electric heat, dryer |
With solar charging on sunny days: Duration can extend significantly
Tips to Extend Battery Life During Outage
- Turn off non-essential lights
- Avoid high-draw appliances (AC, electric heat, dryer)
- Charge phones during day when solar is producing
- Open fridge minimally to keep food cold longer
- Use natural light during daytime
Related Articles
- [[power-outage-behavior|What Happens to My Solar System During a Power Outage?]] — How backup mode works
- [[backup-reserve|What Is Backup Reserve and How Should I Set It?]] — Optimizing your backup capacity
- [[battery-faq-enphase|Battery FAQ — Enphase]] — Common Enphase battery questions
- [[battery-faq-tesla|Battery FAQ — Tesla Powerwall]] — Common Tesla battery questions
Questions? Contact Customer Success at 800-203-4158.