#SolarMOOC: PROBLEM SET #1

NABCEP Exam Practice Problems

Saturday 3/3/12

PROBLEM #1:

A home is located in a town in the valley of a mountainous area at an elevation of 5,280 feet above sea level. To the south is a 20-mile wide cliff mountain ridge that runs east-to-west with an elevation of 11,500 above sea level. The latitude of the town is 40° N.  At 4:00 p.m. on December 21st, the solar altitude angle is at 6°, and shading is just beginning to occur. How far away is the home from the base of the mountain?  Choose the closest answer.

  1. 6,220 ft.
  2. 23,213 ft.
  3. 59,179 ft.
  4. 43,978 ft

 

PROBLEM #2:

A bipolar PV array has outputs of +244 V and -244 V under standard test conditions. The modules are crystalline silicon, and the manufactures coefficients have not been provided.  Assuming the lowest expected temperature is -19° C, what is the expected maximum system voltage of the array?  Choose the closest answer.

  1. 488 V
  2. 288 V
  3. 576 V
  4. 600 V

 

PROBLEM #3:

A carpenter and his wife live on a ranch in Ocala, FL. They have horses, and a shop where the carpenter makes wooden furniture. The property is located at 30° North Latitude. The couple attends church or volunteers at the Church Thrift Store in the mornings, but generally return to the ranch at lunchtime. They have recently decided to build a new stable on the North side of the pasture and want to install a 8 kW PV system on the barn.

Which orientation and roof pitch for the long-side roof would produce the most annual utility savings?

  1. magnetic south, 40°pitch
  2. true southwest, 20° pitch
  3. true southeast, 30° pitch
  4. true south, 30° pitch

 

PROBLEM #4:

 A PV Array is installed in a location that has an expected low temperature of -7° C. The installation includes a 5 kW Bimodal 240V Inverter. The location receives on average 5 Peak Sun Hours per day. What is the maximum current expected between the inverter and the AC Disconnect?  Choose the closest answer.

  1. 21 Amps
  2. 32.5 Amps
  3. 26 Amps
  4. 23 Amps

 

PROBLEM #5

Two dissimilar crystalline silicon PV modules are connected in parallel. The STC rated Isc of module A is 2.3 Amps. The STC rated Isc of module B is 4.3 Amps. What would the measured current be under STC at short circuit with the modules in parallel?

  1. 4.6 A
  2. 6.6 A
  3. 8.6 A
  4. you cannot connect modules in parallel that have different currents.

***Please post your answer to these problems in the forum, or via twitter.  We will post our version of the answers with some explanation tomorrow (Sunday 03/04/12).  Enjoy!!!

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