NABCEP Energy Storage 3

Question 1

When sizing a battery bank for a 3-day autonomy requirement with a daily load of 6 kWh and a maximum depth of discharge of 50%, what minimum capacity is required?

Accepted Answer

36 kWh

Answer

Required capacity = (daily load × days) / DoD = (6 kWh × 3) / 0.50 = 36 kWh.

Question 2

What is the term for the gradual reduction in a battery's maximum capacity over repeated charge-discharge cycles?

Accepted Answer

Cycle degradation

Answer

Cycle degradation refers to the loss of battery capacity that occurs incrementally with each charge-discharge cycle due to physical and chemical changes in the electrodes.

Question 3

In a DC-coupled battery storage system, the battery charge controller is connected between the PV array and the battery bank. What is a key advantage of this configuration?

Accepted Answer

Higher overall system efficiency due to a single DC-to-AC conversion

Answer

DC-coupled systems avoid a double conversion (DC→AC→DC) when charging the battery from solar, resulting in higher overall efficiency.

Question 4

Which temperature condition most severely reduces the available capacity of a lead-acid battery?

Accepted Answer

Low temperatures below 0°C

Answer

Cold temperatures significantly reduce lead-acid battery capacity because the chemical reactions slow down, making less energy available for discharge.

Question 5

A battery-based inverter/charger is classified as a 'multimode inverter.' What capability does this describe?

Accepted Answer

Functioning in both grid-tied and off-grid modes

Answer

A multimode inverter can operate in grid-tied mode, switch to off-grid (island) mode during outages, and transition seamlessly between the two.

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

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

NABCEP Energy Storage 3