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2012-12-23 17:50:31
photovoltaics JATC IBEW solar

from Photovoltaic Systems: 3rd edition, James P Dunlop
Show Answers:

  1. List three types of configurations of the solar array and the most common type. PP 4
    Utility supplemental and standalone. The most common configuration is a utility connected system 
  2. Find the inverse square law as relates to photovoltaics. Pp 31
    A physical law that states that the amounts of radiation at points are proportional to the inverse of the square of their distances from the source. 
  3. Defined distributed generation. PP 26 
    A system in which many smaller powergenerating systems create electrical power near the point of consumption.
  4. PV systems operating in parallel with the utility system, referred to as what systems? WB PP 1
    Multimodal, distributed, interactive, or stand alone?
  5. PV systems operated independently of other power systems are, referred to as what type of systems? WB PP 1
  6. While PV cells produce only _______ power, PV systems can produce ______ power. WB PP 2
    Cells produced DC power and PV systems can produce AC power 
  7. Balance of system (BOS) components typically include all but what? WB PP 2 
    PV modules and inverters. 
  8. List of three main components of the electric utility system. WB PP 3 photovoltaics
    Generation, transmission, and distribution
  9. The first practical Silicon solar cell was made in what year? WB PP 4
  10. Solar power and solar energy is commonly expressed in what units? WB PP 5
    Solar power is commonly expressed in watts per square meter  Solar energy is commonly expressed in watt hours per square meter.

    Note: solar power is used to estimate the output of the PV modules and arrays over time.
  11. If the solar energy received on a surface is 14 kWH per meter square and there are 12 hours of daylight how many peaks hours are available? WB PP 6
    • 4000/1000 = 4
    • Solar Energy/ Peak Sun Watts M2 = peak hrs
  12. What is the formula for solar radiance on the surface involving time? WB PP 6
    • H = (E average) x T 
    • Where H = solar radiation in watt hours per meter squared
    • E average = average solar radiation and watts per meter squared and
    • T = time in hours 
  13. The peak solar radiance incident on the earths surface is approximately what percentage of extraterrestrial irradiance? WB PP 7
  14. List three atmospheric effects on solar radiation. WB PP 7
    Scattering, reflection, and absorption 
  15. Air mass is a representation of what? WB PP 8

    What value of Air mass is considered representative of average terrestrial conditions in United States and used as a reference condition rating modules and arrays? 
    Relative distance of atmosphere that radiation must travel through to reach the earth's surface 

    AM 1.5 
  16. What three components of the electromagnetic spectrum are contained in solar radiation? WB PP 9
    Ultraviolet, invisible, and infrared. 
  17. The orientation of PV arrays is defined by their what? WB PP 15
    Array tilt and array azimuth
  18. To maximize wintertime output PV arrays are generally tilted at an angle close to what? WB PP 15
    Lattitude + 15 degrees
  19. What is the formula for roof slope angle? WB PP 23
    Theta (angle) = Tan-(Rise/ Run)
  20. What is a monopole array? PP 155
    An array that has one positive terminal and one negative terminal
  21. What is a bipolar array? PP 155
    A bipolar array is an array tha has two terminals, one positive and one negative, and a third terminal connected at a center tap.
  22. What is a Photovoltaic effect? PP 154
    A photovoltaic effect is the movement of electrons within a material when it abords photons with energy above a certain level.
  23. The maximum power voltage (Vmp) and maximum power current (Imp) both share what definition? PP 155
    is the operating voltage/ current on an I-V curve where the power output is at maximum.
  24. A p-type semiconductor is a semiconductor that has what? PP 154
    A p-type semiconductor is a semiconductor that has electrond voids.
  25. An N-type semiconductor is a semiconductor that has what? PP 154
    An N-type semiconductor is a semiconductor that has free electrons.
  26. Bypass diodes do what for a PV device and under what condition or why? PP 154
    Bypass diodes protect PV devices form damage and excessive loss of power by directing current around shaded or damaged devices. Remember: Voltage is additive in series and thus current is constant, and since sunlight is directly proportional to current production then a shaded panel would have lower current and would become a load. resulting in damage.
  27. What affcts the magnitude and postion of the I-V curve? PP 154
    solar irradiance and cell temperature.
  28. Bypass diodes are typically installed around groups of _____ to ______ series-connected cells. PP 148
    • Bypass diodes are typically installed around groups of 12 to 18 series-connected cells. 
    • Note: bypass diodes must be able to handle the maximum operating voltage for the number of cells or modules bypassed, and mut be rated in excess of the maximum circuit current.
  29. Define a bypass diode. PP 148
    A bypass diode is a diode used to pass current around, rather than through, a group of PV cells.
  30. A bypass diode allows a reverse bias of only ______ volts. PP 148
    .7 volts
  31. Most modules are rated for a maximum system voltage of ______, though some are rated as high as _______. PP 148
    • 600v
    • 1000v
  32. What should be remembered about PV devices and thier current rating? PP 144
    It should always be remembered that PV devices of different current rating should never be connected is series since "...the current output for a circuit of disssimilar devices in series is limited to the current of the lowest-current output devide in the entire string."
  33. What should you remember about the juction box on a PV module if available? PP 144
    That the PV module may be configured for the ability to change the series or parallel configuration with certain jumper arrangements.
  34. The top and bottom surface of a PV cell or module is of what type of silicon junction and polarity? PP 144
    The top is negative (N type) and the bottom is positive (p type). PP 126
  35. Concerning the photo voltaic effect, what is associated with shorter wavelengths and higher freqeuncies? PP 125
    Higher energy.
  36. Finish the sentence: The absence of a negative charge is considered a ___________. PP 124
    positive charge carrier.
  37. A rectifier converts? PP 120 

    A converter....

    An inverter....
    A rectifier converts AC to DC.

    A converter converts DC to a different voltage level.

    An inverter converts DC power to AC power.
  38. Define a type of standalone system where the output of the PV module or a ray is directly connected to the DC load. PP 120 
    A direct coupled PV system.
  39. Define an electro-chemical device that uses electricity to split water into hydrogen and oxygen PP 120 
    An electrolyzer
  40. What is Islanding? PP 120 
    Islanding is the undesirable conditions where a distributed generation power source, such as a PV system, continues to transfer power to the utility grid during a utility outage.
  41. Define a multi-mode system. PP 120
    A multi-mode system is a PV system that can operate in either utility interactive or standalone mode and uses battery storage.
  42. Concerning net metering, using this system, energy suppling the utility PV system is effectively credited to the customer at what retail value? PP 113
    At full retail value.
  43. What type of PV system is the simplest and least expensive PV system that produces AC power because they require the least components and do not use batteries? PP 113 
    The utility interactive system that operates in parallel with and is connected to the electric utility grid. 
  44. Utility interactive inverter output is determined by what?  Whereas the output from battery based inverters,  is determined by what? PP 102
    Utility interactive inverter output is determined by the DC input from the array unlike the output from battery based inverters, which is determinedby the load.
  45. What type of inverter is used exlusively in PV systems?
    static inverters. PP 224 A static inverter is a device that converts a dc voltage to a stable ac voltage for use in an uninterruptible power system.
  46. inverters for PV systems are broadly classified as what? PP 226
    either stand alone or interactive.
  47. What size are String inverters, central inverters, and utility scale inverters? PP 227
    • String inverters: small 1kw to 12 kw residential
    • central inverters: large utility interactive 30kw-500kw
    • utility scale inverters: very large 500kw-1MW and bigger
  48. For a stand alone PV system what determines the inverter's power rating? PP 226
    The AC load rather than the DC power source.
  49. Inverters for PV systems are broadly classified as what? PP 226
    Either stand alone or interactive