Quick Answer
Off-grid solar systems can power air conditioning units, but it requires careful system design and sizing to ensure sufficient energy production and storage to meet the AC unit's demands.
Calculating Cooling Demand
To power an air conditioning unit with an off-grid solar system, the first step is to calculate the cooling demand in watt-hours (Wh) per day. This involves multiplying the AC unit’s watts (W) by the hours of operation per day. For example, a 1-ton AC unit operating 8 hours a day requires 7,200 Wh (1,000 W x 7.2 hours). Next, calculate the cooling demand in kilowatt-hours (kWh) per day by dividing the Wh value by 1,000.
Sizing the Solar Panel Array
To meet the cooling demand, the solar panel array must produce at least the same amount of energy in watt-hours (Wh) per day. A general rule of thumb is to oversize the solar panel array by 10-20% to account for system losses and inefficiencies. For a 7,200 Wh per day cooling demand, a 9,000 Wh per day solar panel array (1.25 kW) would be necessary. Use a solar panel array sizing worksheet to determine the required panel count, size, and orientation.
Inverter and Battery Sizing
To store excess energy produced by the solar panel array during the day for use at night or during periods of low sunlight, a battery bank is required. The battery bank should be sized to store at least 2-3 days’ worth of the cooling demand in Wh. For a 7,200 Wh per day cooling demand, a 14,400 Wh (16 kWh) battery bank would be necessary. The inverter must be sized to handle the total AC unit load and the battery bank’s maximum discharge rate. A 5 kW inverter with a high surge capacity (20-30 kW) would be suitable for this application.
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