Off Grid Power Calculator – Design Your Complete Off-Grid Battery & Solar System
This free off-grid power calculator helps you determine exactly how much battery capacity you need — with or without solar panels. Whether you power a camper van, RV, boat, tiny home or remote cabin, the tool calculates your real daily energy consumption and shows you the ideal battery size, autonomy level and (optional) solar panel requirements
How This Off-Grid Power Calculator Works
Your results include three key components:
1. Daily Energy Consumption (Wh/day)
This represents the total amount of energy you need to run all your devices every 24 hours. It’s the foundation for determining your battery and optional solar requirements.
2. Recommended Battery Capacity
The calculator shows how many amp-hours (Ah) you need based on:
- Your system voltage (12V, 24V, 48V, or custom)
- Your chosen battery type (LiFePO4, Lithium, or Lead-acid)
- Your autonomy preference — how many days you want to operate with no sun
This makes the tool perfectly useful even if you do not want solar panels.
3. Optional Solar Panel Sizing
If you choose solar or want help sizing panels, the tool will calculate:
- Daily solar production
- Percentage of your system covered by solar
- How many watts of panels you should install for full recharge
If you select “no solar”, the tool focuses purely on battery autonomy.
FAQ – Off Grid Power Calculator
This calculator is ideal for anyone designing an off-grid electrical system, including camper van
and RV owners, boat and liveaboard users, tiny homes, remote cabins, off-grid workshops, and people
preparing emergency backup power. It works for battery-only systems or hybrid setups with solar panels.
The results from this off grid power calculator are highly realistic for practical use. It takes into
account device wattage, daily usage hours, battery chemistry, system voltage, sun hours and depth of
discharge (DOD). Actual performance may vary slightly due to weather, temperature, wiring quality and
component efficiency, but the estimates are accurate enough to design a reliable system.
Yes. You can select “no solar” and the calculator will size a battery-only system based on how many
days you want to run without sunlight. This is useful for sheds, workshops, boats, shaded locations
or emergency backup systems where solar is not practical.
Absolutely. The calculator supports different battery chemistries, including LiFePO4, Lithium and
Lead-acid (AGM, Gel, Flooded) by applying realistic depth of discharge values. This means the
recommended battery capacity matches the actual usable energy of your chosen battery type.
Yes. You can choose between 12V, 24V and 48V systems, or enter a custom voltage. The tool automatically
converts your daily energy use (Wh) into the correct battery size in amp-hours (Ah) based on your selected
system voltage.
Yes. The calculator is perfect for mobile off-grid systems. You can include typical loads such as 12V fridges,
lighting, fans, water pumps, routers, navigation equipment and inverter usage. The output shows how much
battery capacity and optional solar power you need to stay fully powered on the road or at sea.
Yes. You can add any custom device by entering its name, wattage, daily usage hours and quantity. The calculator
will include these custom loads in your total daily energy consumption and adjust the recommended battery and
solar sizing accordingly.
Autonomy defines how many days your system should work without any solar input. The higher the autonomy,
the larger your battery bank needs to be. If you set “Always autonomous”, the calculator aims for a system
that can recharge fully during a normal sunny day and keep you powered even in less ideal conditions.
For most modern off-grid systems, LiFePO4 batteries are the best choice. They offer high usable capacity,
long cycle life, good efficiency and low weight. Lead-acid batteries can still work, but they require more
capacity to deliver the same usable energy and typically have a shorter lifespan under deep cycling.
Yes. The calculator is beginner-friendly while still being accurate enough for advanced users. You don’t
need any engineering background: just enter your devices, usage time, system voltage and preferences, and
the tool will handle the complex calculations for you.