Inverter Battery Backup & Solar Runtime Calculator
Estimate inverter backup time, solar runtime, battery endurance, recharge time, and electricity savings using real engineering calculations. Everything runs 100% locally inside your browser.
Battery Bank Configuration
Use the chemistry's recommended DoD limit
Total Running Load
Inverter & Efficiency
Effective efficiency: 85%
Affects grid recharge time calculation.
Solar & System Mode
Enable to include solar charging in runtime & savings.
At continuous load of 300 Watts (System efficiency 85%)
Backup Hours by Battery Capacity
At current load (300W):
| Battery Ah | Usable Wh | Backup Time |
|---|---|---|
| 100 Ah | 739 Wh | 2h 2m |
| 120 Ah | 887 Wh | 2h 26m |
| 150 Ah | 1109 Wh | 3h 3m |
| 180 Ah | 1331 Wh | 3h 39m |
| 200 Ah | 1478 Wh | 4h 4m |
| 220 Ah | 1626 Wh | 4h 28m |
| 250 Ah | 1848 Wh | 5h 5m |
| 300 Ah | 2218 Wh | 6h 6m |
About Inverter Battery Backup & Solar Runtime Calculator
The Inverter Battery Backup & Solar Runtime Calculator is an advanced, engineering-grade tool designed to accurately predict how long your battery bank will power your home, office, or off-grid facility during power outages.
Unlike generic online calculators that merely divide battery Watt-hours by connected load, this calculation engine incorporates real-world physics: battery Depth of Discharge (DoD) limits, Peukert's law for high-current discharge strain, ambient temperature derating, battery age deterioration, inverter conversion efficiency, and wiring transmission losses.
Whether you are operating a standard home UPS, a standalone off-grid solar system, a net-metered grid-tied setup, or a hybrid inverter with intelligent solar priority, this tool gives you instant, transparent calculations right in your browser with zero server tracking.
Why Use This Inverter & Solar Calculator?
Basic formulas overestimate runtime by 25% to 40% because they ignore inverter standby drain, voltage sag, wiring loss, and depth-of-discharge cutoffs. Our engine computes the exact usable energy chain.
Compare Tubular Lead-Acid, Flat Plate, Gel, AGM, and Lithium Iron Phosphate (LiFePO4) batteries with their specific discharge curves and lifecycle characteristics.
Estimate total wattage using individual home appliances (fans, refrigerators, TVs, laptops, pumps) with automated startup inrush surge detection to ensure your inverter VA capacity won't trip.
Model solar PV generation with MPPT or PWM charge controllers, evaluate solar direct self-consumption, battery recharge times, and projected grid electricity bill savings.
How To Use the Inverter & Solar Calculator
Select Mode & Battery
Choose your system type (UPS, Off-Grid, Grid-Tied, or Hybrid). Pick your battery chemistry, voltage (12V, 24V, 48V), Ah capacity, and battery count.
Input Load & Solar
Enter your total continuous wattage directly, or select quantities of standard appliances. If using solar, input your PV panel wattage and peak sun hours.
Get Instant Results
View precise backup hours, recharge duration, solar generation coverage, surge headroom, and recommended inverter rating — all calculated live in your browser.
Battery Bank Wiring & Efficiency Notes
Series Connection
Connecting batteries in series increases voltage. Capacity (Ah) stays the same.
Parallel Connection
Connecting batteries in parallel increases capacity (Ah). Voltage stays the same.
Battery connections affect system voltage and capacity. Make sure your batteries are compatible and follow your inverter/battery manufacturer's wiring requirements.
Inverter efficiency: Estimated energy lost during inverter operation and DC-to-AC conversion is factored into every runtime result, so the backup hours shown reflect usable output power rather than raw battery energy.
Battery chemistry: Compare Tall Tubular Lead-Acid, Flat Plate, Gel, AGM, Lithium Iron Phosphate (LiFePO4), and Lithium-Ion (NMC) batteries with their specific discharge curves and lifecycle characteristics.
Frequently Asked Questions
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⚠️ Disclaimer
This calculator provides engineering estimates for planning and educational purposes only. Actual battery backup time will vary based on battery brand quality, specific discharge rates, ambient temperature, wiring condition, and inverter make. Always consult a qualified electrical engineer before sizing a critical power system.
🛡️ Privacy Focused
All calculations run entirely in your browser. No battery data, load inputs, or solar configurations are ever sent to any server.
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