NABCEP PV System Design Principles 4

Question 1

In a battery-based PV system, the depth of discharge (DOD) limit for lead-acid batteries is typically set at 50% to:

Accepted Answer

Extend battery cycle life and prevent sulfation damage

Answer

Limiting DOD to 50% significantly extends lead-acid battery cycle life by reducing sulfation and plate degradation.

Question 2

Which performance ratio (PR) range is considered typical for a well-designed, operational grid-tied PV system?

Accepted Answer

0.75 to 0.85

Answer

A performance ratio of 0.75–0.85 accounts for typical real-world losses including temperature, wiring, inverter efficiency, and soiling.

Question 3

The 'clipping' loss in a PV system occurs when:

Accepted Answer

The array's DC output exceeds the inverter's maximum AC output capacity

Answer

Clipping happens when irradiance is high enough that the array produces more DC power than the inverter can convert, causing the inverter to limit output.

Question 4

The DC-to-AC ratio (also called inverter loading ratio or ILR) of 1.2 for a PV system means:

Accepted Answer

The DC nameplate capacity is 1.2 times the inverter's AC output rating

Answer

An ILR of 1.2 means the array's STC DC capacity is oversized by 20% relative to the inverter's rated AC output, which is common to optimize annual energy yield.

Question 5

An azimuth angle of 180° for a fixed-tilt PV array in the northern hemisphere indicates the array faces:

Accepted Answer

Due south

Answer

In the northern hemisphere, true south (180° azimuth) maximizes annual solar irradiance for a fixed-tilt array.

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test

NABCEP PV System Design Principles 4