Off-Grid Battery Calculator
Size a complete off-grid battery bank using your daily energy use, autonomy days, battery chemistry assumptions, and system voltage.
Off-Grid Battery Bank Tool
Enter your daily load, autonomy days, usable depth of discharge, and system voltage to estimate the battery bank size needed for cabins, homes, and farms.
Off-Grid Sizing Estimator
This calculator uses common off-grid sizing rules based on energy use, autonomy, battery voltage, and depth of discharge.
Calculation Results
These results show the estimated battery bank size required for your off-grid system in Wh, kWh, and Ah.
Educational Estimates Only: Actual off-grid battery design also depends on inverter surge, charging sources, weather, wiring losses, reserve margin, battery chemistry, and seasonal use. Verify with datasheets and full system design calculations for critical use.
Off-Grid Rules
Off-grid systems should be sized around real daily energy use, desired autonomy, matching inverter voltage, and a battery chemistry suited to repeated cycling.
Off-grid battery sizing usually starts with daily load in watt-hours, then adds autonomy days to cover periods with limited charging. After that, divide by the usable depth of discharge to estimate the nominal battery bank size required.
For many off-grid homes, 48V systems are preferred because they reduce current, support larger inverters more effectively, and help keep cable sizes manageable. LiFePO4 is often chosen for off-grid use because it offers long cycle life and strong deep-cycle performance.
As a simple rule of thumb, a small cabin system may use around 48V 100Ah, a home may use 48V 200Ah to 400Ah, and a larger farm or high-load property may need 48V 600Ah or more.
Off-grid rules
- Account for 1–3 days autonomy.
- Prefer 48V systems.
- Choose LiFePO4 for lifespan.
- Match inverter voltage.
Examples
- Cabin: 48V 100Ah.
- Home: 48V 200–400Ah.
- Farm: 48V 600Ah+.
What battery for off-grid home?
Usually 48V LiFePO4, sized to your daily Wh load and autonomy days. This setup is common because it balances efficiency, inverter compatibility, and cycle life.
Do I need a generator too?
A generator is optional, but many off-grid systems keep one as backup for long cloudy periods, seasonal peaks, or emergency charging.
Frequently Asked Questions
These are common questions about off-grid battery bank sizing, system voltage, autonomy, and backup planning.
What battery for off-grid home?
Usually 48V LiFePO4, sized to your daily Wh load and autonomy days.
Do I need a generator too?
Optional as backup for long cloudy periods.
How many autonomy days should I use?
Many off-grid systems are planned around 1 to 3 days of autonomy, depending on weather, season, and charging sources.
Why is 48V preferred?
Because it lowers current, supports larger inverters, and can reduce cable size and losses.
Why choose LiFePO4?
LiFePO4 is often preferred for off-grid use because it offers long cycle life and deep-cycle capability.
Should battery voltage match inverter voltage?
Yes. The battery bank should match the inverter's DC input voltage rating.
Can I use this for cabins and farms too?
Yes. The same basic sizing method applies to cabins, homes, farms, and backup power systems.
Do I need extra margin?
Usually yes, because actual energy use, inverter losses, and seasonal conditions can increase battery needs.
Is this result exact?
No. It is an educational estimate and should be checked against actual loads and equipment specifications.
Can I expand later?
Often yes, if your battery system and inverter are designed for modular expansion.
Plan Off-Grid Power Better
Use this calculator to estimate the battery bank size your off-grid system needs, then compare related tools for solar and home backup planning.
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