NABCEP PV System Design Principles 2

Question 1

When sizing a PV array for a battery-based off-grid system, which factor most directly determines the minimum array size?

Accepted Answer

Peak sun hours at the site

Answer

The inverter's surge rating

Answer

Battery float voltage

Answer

Module temperature coefficient

Question 2

A PV system is designed with modules having a temperature coefficient of Pmax of -0.35%/°C. If STC is 25°C and the cell temperature reaches 65°C, by what percentage does output power decrease?

Accepted Answer

14%

Answer

22.75%

Answer

8.75%

Answer

3.5%

Question 3

In a grid-tied PV system, the primary function of the inverter is to:

Accepted Answer

Convert DC power from the array to AC power for the grid

Answer

Store excess energy in batteries

Answer

Step up the array voltage to transmission levels

Answer

Regulate battery state of charge

Question 4

Which NEC article primarily governs the installation of photovoltaic systems?

Accepted Answer

Article 690

Answer

Article 705

Answer

Article 702

Answer

Article 480

Question 5

The 'fill factor' (FF) of a PV module is best described as:

Accepted Answer

The ratio of maximum power to the product of Voc and Isc

Answer

The ratio of active cell area to total module area

Answer

The percentage of incident light converted to electricity

Answer

The number of cells in series divided by total cell count

Question 6

When designing a string of PV modules for a string inverter, the maximum string voltage must not exceed:

Accepted Answer

The inverter's maximum DC input voltage rating

Answer

The combined Vmp of all modules

Answer

690 volts per NEC requirements

Answer

The utility grid voltage multiplied by 1.25

Question 7

Which shading scenario causes the greatest power loss in a series-connected PV string?

Accepted Answer

One module completely shaded

Answer

Uniform light shading across all modules

Answer

Partial shading of the bottom row only

Answer

Shading of only one cell in each module