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What size inverter for 4kW AC w/ 48V 400Ah battery and 12-panel 350W array?

Photovoltaic Inverter

To determine the appropriate size inverter for your solar power system, we need to consider the total output of your solar array, the capacity of your battery bank, and the power requirements of your 4kW air conditioning unit.

Here’s a step-by-step calculation:

Solar array output: You have a 12-panel solar array, each with a 350W rating. The total output is:

12 panels * 350W = 4200W (4.2kW)

Battery bank capacity: You have a 48V, 400Ah battery bank. To find the energy storage capacity in watt-hours (Wh), multiply the voltage by the amp-hour rating:

48V * 400Ah = 19200Wh (19.2kWh)

Air conditioning unit power requirement: Your AC unit requires 4kW of power.
Now, let’s determine the inverter size.

Ideally, the inverter should be able to handle the peak power requirement of your AC unit and support the continuous operation of the system.

For a 4kW AC unit, it’s recommended to have an inverter with a capacity of at least 20-25% more than the AC’s power requirement to account for inefficiencies and potential power surges.

So, the inverter size should be:

4kW * 1.25 = 5kW (minimum)

Considering the solar array output and battery bank capacity, a 5kW inverter should be sufficient for your system.

However, it’s important to consider other factors that may affect the inverter sizing, such as other loads or appliances connected to the system, and whether you require simultaneous operation with the air conditioning unit.

If you have additional loads or expect to run multiple appliances simultaneously with the AC unit, you may want to consider a larger inverter to accommodate the increased demand.

To determine the appropriate inverter size, add up the power requirements of all your appliances and apply the same 20-25% buffer as before.

For example, if your total load requirement is 6kW, the recommended inverter size would be:

6kW * 1.25 = 7.5kW

In conclusion, while a 5kW inverter should be sufficient to support the operation of your 4kW AC unit with the given solar array and battery bank, it’s important to take into account any additional loads or simultaneous appliance usage to determine the most suitable inverter size for your system.