PV System Mechanical Design Flashcards

Use this deck to learn about all of the mechanical design aspects of a PV system installation.

1
Q

You check the polarity of the PV output before applying ______ to ______.

A

PV power to an inverter, a charge controller, batteries, or a load

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2
Q

The battery bank for a battery backup utility-interactive PV system is located in a harsh environment with temperature and humidity extremes. What are the most likely effects on the battery’s state of charge?

A

Undercharged in cold weather and overcharged in hot weather

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3
Q

A 1/4” x 3 1/2” lag screw that has a 3” thread is used to attach an L- bracket to an asphalt-shingle roof. If the combined thickness of the L- bracket, shingles, and roof membrane is 3/4”, and if the screw penetrates directly into a roof truss made of Southern Yellow Pine into a properly sized pilot hole, then what is the withdrawal resistance?

A

773 Ohms

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4
Q

In a PV system, which equipment is colored in green?

A

The grounding conductors

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5
Q

If your magnetic compass is in San Francisco, CA and is showing that your array is aiming to the heading of 189 degrees, what is the azimuth of solar (true) south?

A

-24 degrees

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6
Q

In DC PV systems, what is the function of bare copper?

A

It’s usually not carrying substantial current

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7
Q

Of the following site assessment tools, which are most often needed to determine optimal array placement?

  • sun path analyzer
  • pliers
  • Inclinometer
  • compass
  • voltmeter
A

Compass, inclinometer, and sun path analyzer

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8
Q

A PV array for a utility-interactive system is to be ground-mounted on a hill 1,000 feet from the point of utility connection. It uses a 240 V inverter, and a single string of 1W modules operates between 300 and 550 volts DC. There is a small building halfway between the array location and the utility point of connection. To minimize wire size, increase performance, and ensure consistent operation, where should the inverter be installed?

A

At the utility point of connection

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9
Q

What does green mean in an AC system?

A

Ground

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10
Q

Under what conditions does thin-film PV respond less than polycrystalline PV?

A

Heat and shading

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11
Q

What is the required minimum working space width in front of a 48 V lead acid battery bank?

A

30” or the width of the battery bank, whichever is greater

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12
Q

Areas of low wind, latitude greater than 30 degrees, and minimal daytime summer cloud cover are optimal conditions for what?

A

Two-axis tracking mount

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13
Q

A PV array for a utility-interactive system is to be ground-mounted on a hill 1,000 ft from the point of utility connection. The single string of 1W modules operates between 300 and 550 volts DC. The inverter is a 240 V inverter. There is a small building halfway between the array location and the utility point of connection. The utility point connection will do what for the inverter?

A

Minimize wire size, increase performance, and ensure consistent operation.

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14
Q

What is the cost advantage of thin-film?

A

Can be cheaper per watt to produce

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15
Q

PV systems located far south should do what to optimize performance?

A

Increase the tilt angle

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16
Q

Four PV modules, each with an area of 10 ft2, are to be mounted with a stand-off mount secured to a metal seam roof with L-brackets. If the modules can withstand a load of 75 lbs/ft2, and it is desired to support the full load with one lag screw in each bracket, and each screw has a withdrawal resistance of 300 lb/in2 including a safety factor of 4, the minimum screw thread length to penetrate would be…

A

1.67”

17
Q

A proposed PV installation site has an unobstructed south-facing roof area of 60 m2. If thin-film modules with six watts-per-square-foot power output at STC are to be installed on 50% of the roof, then the maximum available PV array output power (based on the sum of module ratings) at STC will be…

A

1900 watts

18
Q

As it relates to PV system mechanical design, the closer you are to the north, what action will optimize performance?

A

Decrease your tilt angle

19
Q

A small conductor between the array and the inverter is a characteristic of a 500 V DC PV array and gives it an advantage over what kind of array?

A

A 48 V DC array of the same wattage

20
Q

What is distributed generation?

A

Smaller systems produce electricity close to consumption needs

21
Q

What is the most important consideration of mounting PV arrays on residential rooftops with regard to energy production?

A

Shading

22
Q

30 inches, or the width of the battery bank, is the required minimum for what?

A

Working space width in front of a 48 V lead acid battery bank

23
Q

Shading is the most important consideration for what?

A

For mounting PV arrays on residential rooftops with regard to energy production

24
Q

It is important to have what in coastal areas where the air contains salt spray?

A

Stainless-steel hardware

25
Q

When many smaller systems produce electricity that meets consumption needs, what is it called?

A

Distributed generation

26
Q

In DC PV systems, what is usually NOT carrying substantial generation?

A

Bare copper

27
Q

Arrays are common components in what?

A

All PV systems

28
Q

Stainless-steel hardware is most important in which areas?

A

Coastal areas where the air contains salt spray

29
Q

A compass, inclinometer, and sun path analyzer are site assessment tools used for what?

A

Determining the optimal array placement

30
Q

Before applying PV power to either an inverter, a charge controller, batteries, or a load, one should first do what?

A

Check the polarity of the PV output

31
Q

Heat and shading have what effect on thin-film PV?

A

Decreased responsiveness, compared to polycrystalline PV

32
Q

What kind of PV system promises to be cheaper per watt to produce?

A

Thin-film