Quick Answer
When sizing off-grid systems, consider the peak sun hours, system losses, and load requirements to ensure adequate energy production and storage. This involves calculating the system's capacity to meet the load, accounting for factors like battery degradation, and selecting components that can handle the expected energy output. Proper sizing minimizes the risk of power outages and extends the lifespan of the system.
Understanding Peak Sun Hours
Peak sun hours (PSH) are a critical factor in sizing off-grid solar systems. PSH represent the average number of peak sun hours per day at a given location. In the United States, for example, states with high PSH include Arizona (6.5-7 hours) and California (5.5-6 hours). Conversely, states with low PSH include Washington (2-3 hours) and Michigan (2-3 hours). To size an off-grid system, consider the average PSH for the installation location.
Calculating System Capacity
To calculate system capacity, start by determining the total load requirements in watts. Divide the total load by the system’s capacity factor (usually 0.75 for off-grid systems) to determine the required power production. Then, consider the system losses, such as inverter efficiency (typically 95-97%) and wiring losses (typically 2-5%). The calculated system capacity should be rounded up to the nearest standard solar panel size (e.g., 300W or 400W) to ensure adequate energy production.
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