Can off-grid solar systems provide power during emergencies?

Understanding the Importance of System Sizing

To ensure off-grid solar systems can provide power during emergencies, it’s essential to properly size the system. This involves calculating the total load of critical devices and appliances, including lights, refrigeration, and medical equipment. For example, a typical medical facility might have a load of 1-2 kilowatts, which would require a battery bank with a minimum capacity of 2-4 kilowatt-hours (kWh) to ensure at least 4-8 hours of backup power.

Calculating Load and Battery Capacity

To determine the required battery capacity, it’s essential to calculate the daily energy demand. This can be done using a load calculation worksheet, which takes into account the system’s peak load, daily load, and backup power duration. For example, if the peak load is 2 kilowatts and the desired backup duration is 8 hours, the daily energy demand would be 16 kWh (2 kW x 8 hours). This would require a battery bank with a minimum capacity of 16 kWh, assuming a 100% depth of discharge (DOD).

Panel and Inverter Sizing

In addition to proper battery sizing, it’s also essential to size the solar panel array and inverter correctly. The panel array should be sized to meet the daily energy demand, taking into account any shading or other losses. For example, a 2-kilowatt (kW) panel array would be required to meet a daily energy demand of 16 kWh, assuming 6 hours of direct sunlight per day. The inverter should be sized to match the panel array and battery bank, ensuring that the system can charge the batteries efficiently and provide power to critical loads during emergencies.