NABCEP Electrical & Mechanical Concepts 2

Question 1

A PV array produces 48 V open-circuit and 8 A short-circuit current. What is the maximum power point voltage most likely to be?

Accepted Answer

38–40 V

Answer

Vmp is typically about 80% of Voc, placing it around 38–40 V for a 48 V Voc array.

Question 2

Which NEC article governs the installation of photovoltaic systems?

Accepted Answer

Article 690

Answer

NEC Article 690 specifically covers solar photovoltaic systems.

Question 3

A solar module has a temperature coefficient of power of -0.4%/°C and is rated at 300 W at STC (25°C). What is its power output at 65°C?

Accepted Answer

252 W

Answer

ΔT = 40°C, derating = 0.4% × 40 = 16%, 300 W × 0.84 = 252 W.

Question 4

What is the purpose of a fused disconnect on the DC side of a PV system?

Accepted Answer

Allow safe isolation of PV source circuits

Answer

A fused DC disconnect allows the array to be safely isolated from the inverter for maintenance or emergencies.

Question 5

In a series-connected PV string, if one module is shaded, what happens to the string current?

Accepted Answer

Current is limited to the shaded module's reduced output

Answer

In a series string, current is limited by the weakest (most shaded) module, reducing total output.

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