Quick Answer
SHADE CAN REDUCE OFF-GRID SOLAR PERFORMANCE BY UP TO 70% DURING PEAK HOURS, LEADING TO INADEQUATE POWER GENERATION AND BATTERY DEPLETION. IT IS CRUCIAL TO CONSIDER SHADING WHEN SIZING AN OFF-GRID SOLAR SYSTEM. FAILURE TO DO SO CAN RESULT IN INADEQUATE SYSTEM PERFORMANCE AND UNMET LOADING REQUIREMENTS.
Assessing Shade Impact
When assessing the impact of shade on an off-grid solar system, it’s essential to consider the type and severity of shading. A tree or building casting a shadow of 20% or less on a panel may have a minimal impact, while a 50% shaded area can significantly reduce performance. Using the solar irradiance values for your location, calculate the expected energy production for a shaded panel versus a clear panel.
Sizing the System for Shade
To account for shade, increase the total system size to compensate for the reduced power output. A common rule of thumb is to add 10-20% to the total system size for every 10% of shading. For example, if the system design calls for 5 kW of power, and there is 20% shading, the system size should be increased to 6-6.5 kW to ensure adequate power generation. Be sure to update the load calculation worksheet to reflect the increased system size.
Shading Impact on Panel Battery Inverter Sizing
Shade can also impact the sizing of the panel, battery, and inverter. A larger system size due to shading may require a more substantial inverter to handle the increased load. Additionally, the battery bank size may need to be increased to accommodate the reduced energy production from shaded panels. When updating the system design, be sure to recalculate the panel battery inverter sizing worksheet to ensure adequate system performance.
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