CSLB C-46 Solar ContractorPhotovoltaic System InstallationMedium
A solar designer is laying out a rooftop PV system where multiple small shading obstructions (e.g., vents, small satellite dishes) are present. To maximize energy harvest and minimize the impact of these obstructions, which type of power electronics should be specified?
- AOversized PV array with a standard string inverter.
- BMicroinverters or DC optimizers at each module.
- CString inverter with two MPPTs per string.
- DCentral inverter with a single Maximum Power Point Tracker (MPPT).
Show answer & explanationAnswer & explanation
Correct answer: B. Microinverters or DC optimizers at each module.
Microinverters and DC optimizers perform MPPT at the individual module level. This allows each module to operate independently at its maximum power point, significantly reducing power losses from partial shading caused by numerous small obstructions across the array, unlike string or central inverters that optimize at a higher aggregated level.
Why the other options are wrong
- A. Oversizing the array might compensate for some losses but doesn't address the fundamental issue of individual module power optimization under shading.
- C. A string inverter with two MPPTs per string is better than one MPPT, but not as effective as module-level optimization for numerous small obstructions.
- D. A central inverter with a single MPPT would suffer significant performance degradation from multiple small shading obstructions.
Module-Level Power Electronics (MLPE)
Devices like microinverters and DC optimizers that perform MPPT and power conversion at the individual PV module level.
- Optimizes power for each module independently.
- Excellent for mitigating partial shading.
- Can provide module-level monitoring.
Memory trick: Small shade, big problem? Module-level tech is the best solution.