NABCEP Solar PV System Design 4

Question 1

What is the standard test condition (STC) irradiance level used when rating PV module output?

Accepted Answer

1,000 W/m²

Answer

STC specifies 1,000 W/m² irradiance, 25°C cell temperature, and AM 1.5 spectrum as the reference conditions for rating PV module output.

Question 2

A battery-based off-grid system needs to power a 1,200W load for 6 hours daily. What is the minimum daily energy storage requirement?

Accepted Answer

7,200 Wh

Answer

Daily energy requirement = 1,200W × 6 hours = 7,200 Wh, which sets the minimum usable battery capacity needed per day.

Question 3

When determining the number of modules per string for a string inverter, which inverter specification sets the upper boundary?

Accepted Answer

Maximum DC input voltage

Answer

The inverter's maximum DC input voltage (e.g., 600V or 1000V) caps the number of modules in series, as string Voc must not exceed this limit.

Question 4

What is the significance of a module's 'fill factor' (FF)?

Accepted Answer

It indicates how closely the module's I-V curve approaches an ideal rectangle

Answer

Fill factor is the ratio of maximum power to the product of Voc and Isc, showing how 'square' the I-V curve is and reflecting overall cell quality.

Question 5

A grid-tied PV system must include anti-islanding protection. What is the primary reason for this requirement?

Accepted Answer

To protect utility workers from energized lines during an outage

Answer

Anti-islanding prevents the inverter from continuing to energize the grid during a utility outage, protecting lineworkers who may be repairing downed lines.

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

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

NABCEP Solar PV System Design 4