How to properly size a solar array for a 24V battery system?

Calculating Required Daily Energy Production

Determine the required daily energy production by calculating the system’s daily load in watt-hours (Wh) and multiplying it by the desired autonomy period in days. For example, if the system has a 200W load and you want a 2-day autonomy period, the required daily energy production is 200W x 24h x 2 = 9600Wh. Consider a 20% buffer for system losses and inefficiencies, resulting in a total daily energy production requirement of 11,520Wh.

Designing the Solar Array

To design the solar array, calculate the required solar array size in watts using the system’s voltage, efficiency, and solar irradiance. A typical 24V system with a 90% efficient solar panel and an irradiance of 200W/m^2 requires a solar array size of approximately 132W (11,520Wh / (24V x 8h)) to meet the daily energy production requirement. To ensure adequate system performance, round up to the nearest multiple of the solar panel’s wattage rating, which is typically 30-50W. In this case, a 150W solar panel would be a suitable choice.

System Sizing Considerations

When sizing a solar array, consider factors such as system efficiency, battery capacity, and load profile to ensure adequate energy production and storage. A well-designed solar array should provide 20-30% more energy than the system’s daily load to account for system losses and inefficiencies. Additionally, consider the solar panel’s temperature coefficient and its impact on energy production, especially in high-temperature environments.