Solar Site and Shading Analysis Flashcards
7 cards from real NABCEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Solar Site and Shading Analysis flashcards as text
A Solar Pathfinder instrument is used at a proposed installation site. What does it primarily measure?
Answer: Percentage of annual solar access blocked by obstructions
The Solar Pathfinder captures a panoramic reflection of surrounding obstructions and overlays a sun path diagram to quantify the percentage of annual solar energy available at that location.
Which shading loss factor specifically accounts for the electrical mismatch caused when one module in a string is partially shaded while others remain unshaded?
Answer: String mismatch loss
String mismatch loss occurs because a shaded module forces its series-connected string partners to operate below their maximum power points, reducing total string output disproportionately.
When performing a shading analysis using simulation software, a designer enters a 'horizon elevation angle' of 12° at azimuth 180°. What does this mean?
Answer: An obstruction 12° above the horizon blocks sun at due south
A horizon elevation angle of 12° at azimuth 180° means that an obstruction (such as a hill or building) rises 12° above the horizontal plane when looking due south from the site.
A site in Phoenix, AZ (latitude ~33°N) has a tree located 10 feet north of the array. At what time of year is this tree LEAST likely to cause shading on the array?
Answer: Summer solstice at solar noon
At summer solstice, the sun reaches its highest elevation angle of the year (approximately 80° in Phoenix), so a tree directly north casts minimal shadow southward onto the array.
The 'irradiance threshold' parameter in PVsyst's shading loss calculation refers to:
Answer: The plane-of-array irradiance level below which shading losses are ignored in the model
PVsyst's irradiance threshold sets the POA irradiance level below which detailed shading calculations are skipped, as low-light periods have negligible energy contribution.
Which instrument uses a fish-eye lens to photograph the sky dome and then analyzes the image to calculate solar access and shading fractions?
Answer: HemisView or SunEye device
The HemisView and Solmetric SunEye are hemispherical (fish-eye) camera tools that capture the full sky dome and overlay sun path diagrams to compute shading-adjusted solar access values.
A commercial rooftop in Chicago has HVAC units that will shade the southern portion of the proposed array. The BEST design strategy to minimize electrical mismatch losses is to:
Answer: Orient shaded modules in separate sub-arrays on distinct MPPT inputs
Placing shaded modules on a dedicated MPPT input allows the inverter to optimize that sub-array independently, preventing shaded modules from dragging down unshaded strings.