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How to choose inverter and battery size

Jan 08,2024 | EASUN OEM

Choosing the right inverter and battery size involves considering your power requirements, the devices you want to run, and the duration you need the system to provide power. Following in EASUN's footsteps, the following steps can help you make the right choice

Inverter Size:

  1. Determine Power Requirements:

    • List all the electrical devices (with their power ratings in watts) that you intend to power with the inverter.
    • Add up the power requirements of all devices you plan to run simultaneously.
  2. Consider Surge Power:

    • Some devices, especially those with motors (e.g., refrigerators, air conditioners), may require a higher initial power surge when starting. Choose an inverter that can handle these surges.
  3. Choose Inverter Size:

    • Select an inverter that has a continuous power rating greater than the total power requirements calculated in step 1.
    • If you have devices with high surge power, ensure that the inverter's peak/surge power rating can handle these.

Battery Size:

  1. Determine Energy Consumption:

    • Calculate the daily energy consumption by multiplying the total power requirements (from the inverter size calculation) by the estimated number of hours each device will be used.
  2. Consider Depth of Discharge (DoD):

    • Batteries should not be fully discharged to maximize their lifespan. Determine the Depth of Discharge (DoD) percentage allowed for the battery type you are considering (e.g., 50%, 70%).
  3. Calculate Required Capacity:

    • Divide the daily energy consumption by the Depth of Discharge percentage to find the minimum battery capacity needed.
    • Battery Capacity (Ah)=Daily Energy Consumption (Wh)DoD
  4. Choose Battery Voltage:

    • Inverters and batteries should have compatible voltage ratings. Common voltages include 12V, 24V, and 48V.
  5. Consider Battery Type:

    • Choose a battery type based on your needs (e.g., lead-acid, lithium-ion). Lithium-ion batteries generally have a longer lifespan and are more lightweight but can be more expensive.
  6. Calculate Number of Batteries:

    • Divide the required battery capacity by the capacity of a single battery to determine the number of batteries needed.
    • Number of Batteries=Required Battery Capacity (Ah)Individual Battery Capacity (Ah)


  • Backup Duration:

    • Determine how long you need the system to provide power during an outage to choose an appropriate battery capacity.
  • Charging Time:

    • Consider the charging time of the battery. Faster charging may be important in areas with unreliable power sources.
  • Solar or Generator Integration:

    • If planning to use solar panels or a generator for recharging, consider their compatibility and the required charge controller.

If you are unsure about calculations or have specific technical requirements, be sure to consult an EASUN professional