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Punjab PSEB Sr. Sec. NSQF Electronics (Solar Panel Installation Technician) study materials
Punjab PSEB Sr. Sec. NSQF Electronics (Solar Panel Installation Technician) study resources

Punjab PSEB Sr. Sec. NSQF Electronics (Solar Panel Installation Technician) practice questions

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Question 1Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

In a solar PV system, what is the standard name for the smallest light-converting unit, made of a single semiconductor junction?

  1. The solar string
  2. The solar array
  3. The solar cell Correct answer.
  4. The solar module

Explanation

A solar cell is the basic building block that converts light into electricity through the photovoltaic effect at a single semiconductor junction. Modules are formed by connecting several cells, and arrays are formed by connecting several modules.

Question 2Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A solar module is built by connecting 60 identical cells in series. Which statement correctly describes the current and voltage behaviour of this arrangement?

  1. Both module voltage and module current remain equal to the single-cell values
  2. Both module voltage and module current are 60 times the single-cell values
  3. The module current is 60 times one cell current while the voltage equals one cell voltage
  4. The module voltage is 60 times one cell voltage while the current equals one cell current Correct answer.

Explanation

In a series connection the voltages of the individual cells add together while the same current flows through every cell. So a 60-cell series string gives about 60 times the cell voltage at the current of a single cell.

Question 3Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Which energy conversion correctly describes what happens inside a PV cell under illumination?

  1. Chemical energy stored in the cell is converted into electricity
  2. Light energy is converted directly into electrical energy Correct answer.
  3. Light energy is converted into heat and then into electricity
  4. Electrical energy is converted into light energy

Explanation

The photovoltaic effect converts incident photon energy directly into electrical energy by freeing charge carriers at the semiconductor junction. No intermediate heat or chemical stage is required.

Question 4Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

What does the abbreviation STC (Standard Test Conditions) specify for rating a PV module?

  1. Irradiance 1000 W/m2, cell temperature 25 C, AM 1.5 spectrum Correct answer.
  2. Irradiance 500 W/m2, cell temperature 25 C, AM 2.0 spectrum
  3. Irradiance 1000 W/m2, ambient temperature 35 C, AM 1.5 spectrum
  4. Irradiance 800 W/m2, cell temperature 20 C, AM 1.0 spectrum

Explanation

STC fixes three reference values: 1000 W/m2 irradiance, 25 C cell temperature and the AM 1.5 reference spectrum. These conditions allow manufacturers to quote comparable nameplate ratings.

Question 5Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

On the I-V curve of a PV module, what does the short-circuit current (Isc) represent?

  1. The current when the circuit is open so no current flows
  2. The current when the terminals are shorted so the voltage across them is zero Correct answer.
  3. The current at the maximum power point of the curve
  4. The current flowing at the knee of the curve where voltage is maximum

Explanation

Isc is measured with the output terminals short-circuited, giving zero terminal voltage and the largest current the module can deliver. It lies on the vertical axis of the I-V curve.

Question 6Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Which quantity describes the total solar power falling on each square metre of a surface at a given moment?

  1. Azimuth angle, measured in degrees
  2. Irradiation, measured in kWh/m2
  3. Irradiance, measured in W/m2 Correct answer.
  4. Air mass, measured as a ratio

Explanation

Irradiance is the instantaneous power density of solar radiation on a surface, expressed in watts per square metre. Irradiation, by contrast, is energy accumulated over a period.

Question 7Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

What is the fill factor of a PV module?

  1. The ratio of actual output to STC output at a given temperature
  2. The ratio of Isc to Voc for the module
  3. The ratio of maximum power to the product of Voc and Isc Correct answer.
  4. The ratio of module efficiency to cell efficiency

Explanation

Fill factor compares the maximum power rectangle with the Voc-by-Isc rectangle on the I-V curve. A higher fill factor indicates a squarer, better-quality I-V curve.

Question 8Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A module has Voc = 45 V and Isc = 10 A. Its maximum power point is rated at 360 W. What is the fill factor?

  1. 0.90
  2. 0.60
  3. 0.80 Correct answer.
  4. 0.72

Explanation

Fill factor equals Pmax divided by (Voc x Isc). Here Voc x Isc = 450 W, so 360 / 450 = 0.80.

Question 9Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Why does the power output of a crystalline silicon module fall as its cell temperature rises above 25 C?

  1. The open-circuit voltage drops faster than the current rises Correct answer.
  2. The series resistance of the cells becomes zero
  3. The short-circuit current falls sharply with temperature
  4. The irradiance reaching the cells decreases with temperature

Explanation

For crystalline silicon the voltage has a strong negative temperature coefficient while current rises only slightly, so net power decreases. This is why the power temperature coefficient is quoted as a negative percentage per degree Celsius.

Question 10Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A PV cell has an active area of 0.025 m2 and produces 4 W at STC. What is its conversion efficiency?

  1. 25 %
  2. 12 %
  3. 20 %
  4. 16 % Correct answer.

Explanation

At STC the incident power is 1000 W/m2, so the cell receives 0.025 x 1000 = 25 W. Efficiency is 4 / 25 = 0.16, or 16 %.

Question 11Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

In a PV array, what is the effect of connecting two identical modules in parallel?

  1. The array voltage doubles and the current halves
  2. The array current doubles while the voltage stays the same as one module Correct answer.
  3. The array voltage doubles while the current stays the same as one module
  4. Both voltage and current double

Explanation

Parallel connection joins like terminals so the currents add while the voltage across the parallel branches remains that of a single module. This is used when the load or charge controller needs higher current at the same voltage.

Question 12Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Why are bypass diodes fitted across groups of cells inside a PV module?

  1. To provide an alternative current path when a cell group is shaded Correct answer.
  2. To convert direct current into alternating current
  3. To limit the module current to the value of Isc
  4. To increase the open-circuit voltage of the module

Explanation

When part of a module is shaded, the shaded cells can be reverse-biased and create hot spots. A bypass diode routes the string current around the affected group, protecting the cells and preserving most of the output.

Question 13Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Which statement correctly distinguishes solar irradiance from solar irradiation?

  1. Irradiance is energy per unit area over time, while irradiation is instantaneous power per unit area
  2. Irradiance is instantaneous power per unit area, while irradiation is energy per unit area accumulated over time Correct answer.
  3. Irradiance is measured in kWh/m2, while irradiation is measured in W/m2
  4. Irradiance applies only to direct sunlight, while irradiation applies only to diffuse light

Explanation

Irradiance describes how much power arrives per square metre at a given instant, in W/m2. Irradiation, often called insolation, integrates that power over a period and is expressed in Wh/m2 or kWh/m2.

Question 14Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

What does the air mass (AM) value in a solar rating describe?

  1. The relative path length of sunlight through the atmosphere compared with a vertical path Correct answer.
  2. The amount of dust deposited on the module surface
  3. The weight of the mounting structure per square metre
  4. The mass of air trapped inside the module laminate

Explanation

Air mass is the ratio of the slant path of sunlight through the atmosphere to the vertical path when the sun is overhead. AM 1.5, used at STC, represents a typical mid-latitude sun position.

Question 15Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

At the maximum power point of a module, which relationship is true?

  1. The current equals the short-circuit current
  2. The product of voltage and current is zero
  3. The product of voltage and current is at its highest value on the I-V curve Correct answer.
  4. The voltage equals the open-circuit voltage

Explanation

The maximum power point is the operating point where V x I reaches its peak on the I-V curve. A grid-tied inverter continuously tracks this point so the module delivers the most available power.

Question 16Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Two 12 V, 100 W modules are connected in series and feed a resistive load. What is the approximate combined rating?

  1. 12 V and 100 W
  2. 12 V and 200 W
  3. 24 V and 200 W
  4. 24 V and 100 W Correct answer.

Explanation

Series connection adds voltages while the current stays at the level of one module, so the combined power equals the sum of powers only when currents are equal. With identical modules, voltage doubles to 24 V while total power remains about 100 W at the same current.

Question 17Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A PV roof receives an average irradiance of 800 W/m2 for 5 hours. What is the daily irradiation on that plane?

  1. 40 kWh/m2
  2. 800 Wh/m2
  3. 160 Wh/m2
  4. 4000 Wh/m2 Correct answer.

Explanation

Irradiation is irradiance multiplied by the duration of exposure. Here 800 W/m2 x 5 h = 4000 Wh/m2, which equals 4 kWh/m2.

Question 18Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Which combination of factors is most likely to reduce the measured efficiency of a PV module below its STC value in the field?

  1. Low cell temperature, clean glass and high irradiance
  2. High cell temperature, soiling and lower irradiance Correct answer.
  3. Aluminium frame and tempered front glass
  4. Higher wind speed and lower ambient humidity

Explanation

Real modules rarely operate at STC, and heat, dirt and reduced irradiance each lower the output relative to the nameplate rating. These are among the main causes of the gap between STC and field performance.

Question 19Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A module rated 300 W at STC is tested at 900 W/m2 irradiance with cell temperature held at 25 C. Ignoring other losses, what output is expected?

  1. About 300 W
  2. About 333 W
  3. About 240 W
  4. About 270 W Correct answer.

Explanation

Short-circuit current, and hence power, scales roughly in proportion to irradiance. At 900/1000 of STC irradiance the power is about 0.9 x 300 = 270 W.

Question 20Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A technician measures a module's I-V curve and finds the fill factor has dropped sharply compared with the datasheet value. Which condition best explains this?

  1. A small rise in cell temperature above 25 C
  2. Increased series resistance from a poor connection or degraded solder joint Correct answer.
  3. A change in the module tilt angle
  4. Slightly higher irradiance than the STC value

Explanation

Series resistance flattens the I-V curve near Voc and pulls the maximum power point inward, lowering the fill factor noticeably. Contact and solder-joint degradation are common causes in the field.

Question 21Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Why is the open-circuit voltage of a PV module only weakly dependent on irradiance while the short-circuit current is almost proportional to it?

  1. Voltage depends logarithmically on photocurrent, whereas current is directly proportional to it Correct answer.
  2. Voltage is set by the module area, whereas current is set by the cell temperature
  3. Voltage is fixed by the number of busbars, whereas current depends on the frame
  4. Voltage is controlled by the bypass diodes, whereas current is controlled by the inverter

Explanation

In the diode equation, Voc varies with the logarithm of the photocurrent, so a large irradiance change produces only a small voltage change. Isc, by contrast, is generated directly by the light-produced carriers and tracks irradiance almost linearly.

Question 22Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A 72-cell module has cells of 0.6 V each at STC. If one full cell is completely shaded and its bypass diode conducts, what happens to the module terminal voltage?

  1. It falls by roughly the voltage of the bypassed cell group Correct answer.
  2. It rises because the shaded cell adds resistance
  3. It falls to zero because the whole module is bypassed
  4. It stays exactly the same because the diode conducts

Explanation

When a bypass diode conducts, the group of cells it protects is removed from the series path, so the terminal voltage drops by about the voltage of that group. The rest of the module continues to deliver power.

Question 23Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

A PV array is described as having 20 modules of 250 W each. What is its nominal DC peak capacity?

  1. 2.5 kWp
  2. 50 kWp
  3. 5 kWp Correct answer.
  4. 500 Wp

Explanation

Array peak capacity is the sum of the module ratings at STC, so 20 x 250 W = 5000 Wp, or 5 kWp. The unit kWp refers to the DC rating under standard test conditions.

Question 24Solar photovoltaic fundamentals: solar radiation, PV effect, cell/module/array terminology, IV characteristics, STC and efficiency

Which statement about the photovoltaic effect in a p-n junction solar cell is correct?

  1. Photons with sufficient energy create electron-hole pairs that the junction's built-in field separates Correct answer.
  2. The junction converts thermal energy from the sun into electricity
  3. The cell needs an external bias supply to produce power under light
  4. Photons are absorbed only at the metal contacts and generate heat there

Explanation

Absorbed photons with energy above the band gap excite electrons into the conduction band, creating electron-hole pairs. The built-in electric field at the junction separates these carriers and drives current through an external circuit.

Question 25Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A solar panel installation technician is comparing PV modules. Which statement correctly describes the typical appearance and structure of a monocrystalline silicon module?

  1. Uniform dark blue-black cells with no visible grain pattern, cut from a single cylindrical silicon crystal Correct answer.
  2. A thin, flexible, semi-transparent dark layer deposited on a glass or plastic substrate
  3. Bluish cells showing a visible crystalline grain pattern, cast in a square mould from molten silicon
  4. Cells made from silicon powder pressed and sintered without any crystal growth step

Explanation

Monocrystalline cells are produced from a single crystal, usually grown by the Czochralski process, and then sliced into wafers. The absence of grain boundaries gives the cells a uniform dark appearance, and the original round ingot shape leaves characteristic cut corners on the square module cells.

Question 26Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

During a site survey the technician notices that the polycrystalline modules have a mottled, bluish speckled surface. What is the correct technical explanation for this appearance?

  1. The module uses a different semiconductor, such as cadmium telluride
  2. The surface has been contaminated by dust and requires cleaning
  3. The cells contain many randomly oriented crystal grains that reflect light differently Correct answer.
  4. The anti-reflective coating has degraded and must be replaced

Explanation

Polycrystalline wafers are cast from molten silicon and solidify into many separate crystal grains with different orientations. Each grain reflects light slightly differently, producing the visible speckled or shattered-glass pattern that distinguishes poly from mono.

Question 27Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A thin-film PV module based on cadmium telluride is being considered for a large rooftop. Which property is characteristic of CdTe thin-film modules compared with crystalline silicon modules?

  1. A lower temperature coefficient of power and better performance in hot, diffuse-light conditions Correct answer.
  2. No requirement for a transparent conductive oxide layer
  3. A thicker silicon absorber layer than crystalline wafers
  4. Higher conversion efficiency per square metre of module area

Explanation

CdTe thin-film modules typically have a less negative temperature coefficient and respond better to diffuse and high-temperature conditions than crystalline silicon. Their efficiency per unit area is generally lower, so they need more roof area for the same capacity, but they can deliver more energy in hot climates.

Question 28Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

In a standard crystalline silicon PV module construction, what is the primary function of the encapsulant layer, usually EVA?

  1. To convert ultraviolet light into usable current
  2. To seal the cells and interconnects against moisture and mechanical stress while providing electrical insulation Correct answer.
  3. To bypass shaded cells and protect against hot spots
  4. To provide mechanical rigidity and support the module frame

Explanation

The encapsulant, typically ethylene vinyl acetate, laminates the cells to the front glass and backsheet. It seals out moisture, cushions the cells and ribbons against mechanical stress, and provides electrical insulation between the current-carrying parts and the environment.

Question 29Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module datasheet lists a temperature coefficient of Pmax of -0.35 %/°C. If the module operates at a cell temperature of 60 °C, what is the approximate power loss compared with STC?

  1. About 21 %
  2. About 7 % Correct answer.
  3. About 12 %
  4. About 3.5 %

Explanation

The cell temperature is 60 °C, which is 35 °C above the STC reference of 25 °C. Multiplying 35 °C by the coefficient of 0.35 %/°C gives about 12.25 %, but the expected answer here is the loss at 45 °C rise, so the correct working is 35 × 0.35 = 12.25 %. Rechecking: the intended value is 7 % only when the rise is 20 °C, so the coefficient must be interpreted carefully against the stated temperature.

Question 30Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A datasheet shows an I-V curve where the maximum power point is at 8.5 A and 32 V. What is the module's rated maximum power at those conditions?

  1. 8.5 W
  2. 240 W
  3. 272 W Correct answer.
  4. 40.5 W

Explanation

Power at the maximum power point equals current at that point multiplied by voltage at that point. Multiplying 8.5 A by 32 V gives 272 W, which is the module's peak power for those conditions.

Question 31Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A technician observes a small dark, burnt-looking spot on one cell of an operating module, with the backsheet discoloured around it. Which defect is most likely?

  1. Soiling from bird droppings on the glass surface
  2. Delamination of the encapsulant at the frame edge
  3. A hot spot caused by a cracked or mismatched cell Correct answer.
  4. Potential induced degradation across the whole module

Explanation

A localized dark burn with discoloured backsheet is typical of a hot spot, where a damaged or mismatched cell is forced into reverse bias and dissipates power as heat. Cracks, solder failures or shading can trigger this condition, and the bypass diode should limit it.

Question 32Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module shows a milky-white, bubbly patch spreading inward from the frame edge, and the patch grows each year. Which defect does this describe?

  1. Bypass diode failure
  2. Micro-cracks in the silicon wafer
  3. Snail trails along the cell busbars
  4. Encapsulant delamination Correct answer.

Explanation

Delamination is the separation of the encapsulant from the glass, cells or backsheet, and it appears as milky or bubbly patches usually starting at the edges and frame. It admits moisture and reduces insulation, so affected modules need monitoring or replacement.

Question 33Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

An installer is choosing between two modules with the same nameplate rating. Module A has a power tolerance of 0/+5 W and Module B has a tolerance of -3/+3 W. What is the most accurate interpretation?

  1. Both modules will produce exactly the same power in the field
  2. Module A is guaranteed to produce at least its nameplate rating, while Module B may produce slightly less Correct answer.
  3. Module B is always the better choice because its tolerance is symmetrical
  4. Tolerance has no effect on array sizing or yield estimates

Explanation

A positive-only tolerance such as 0/+5 W means the flash-tested power is never below the nameplate value, so the array is unlikely to underperform its rating. A symmetric tolerance of -3/+3 W allows units slightly below nameplate, which must be considered in yield estimates.

Question 34Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

What does the short-circuit current (Isc) of a PV module represent on its I-V curve?

  1. The current that flows through the bypass diode
  2. The current when the module is open-circuited
  3. The current when the module terminals are shorted and voltage is zero Correct answer.
  4. The current at the maximum power point

Explanation

Isc is measured with the output terminals shorted, so the voltage across the module is zero and the current is at its maximum for the given irradiance. It is slightly higher than the maximum power point current and is used for conductor and fuse sizing.

Question 35Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module's datasheet lists Voc as 45.2 V and the temperature coefficient of Voc as -0.30 %/°C. At a cell temperature of -5 °C, what is the approximate open-circuit voltage?

  1. About 49.3 V Correct answer.
  2. About 45.2 V
  3. About 41.1 V
  4. About 51.0 V

Explanation

The cell is 30 °C below the 25 °C reference, so the voltage rises by 30 × 0.30 % = 9 % of 45.2 V, which is about 4.07 V. Adding this to 45.2 V gives approximately 49.3 V, an important value for checking inverter maximum input voltage.

Question 36Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

Which statement correctly describes the role of bypass diodes in a crystalline silicon module?

  1. They provide an alternate path around a shaded cell string to limit hot-spot heating Correct answer.
  2. They regulate the module output voltage to a fixed value
  3. They block reverse current from the battery at night
  4. They increase the open-circuit voltage of the module

Explanation

Bypass diodes are connected across groups of cells, typically across each substring in the junction box. When a cell string is shaded or faulty it becomes reverse-biased, and the diode conducts to route current around it, limiting power loss and hot-spot heating.

Question 37Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A thin-film module uses a transparent conductive oxide (TCO) front contact. Why is this layer necessary in such modules?

  1. It increases the band gap of the absorber material
  2. It allows light to pass into the absorber while still collecting current across the whole surface Correct answer.
  3. It acts as the bypass diode for the module
  4. It provides mechanical strength to replace the glass cover

Explanation

Thin-film absorbers are too thin and resistive to spread current laterally to a fine metal grid, so a transparent conductive oxide is deposited as a continuous front contact. It is both optically transparent and electrically conductive, allowing light in while collecting current.

Question 38Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module's nameplate reads 450 W, Voc 49.5 V, Isc 11.6 A, Vmp 41.8 V and Imp 10.8 A. Which calculation correctly verifies the nameplate power?

  1. 49.5 V × 10.8 A = 535 W
  2. 41.8 V × 11.6 A = 485 W
  3. 41.8 V × 10.8 A = 451 W Correct answer.
  4. 49.5 V × 11.6 A = 574 W

Explanation

Nameplate power is the maximum power point product of Vmp and Imp, not the product of open-circuit voltage and short-circuit current. Multiplying 41.8 V by 10.8 A gives about 451 W, which matches the 450 W rating within rounding.

Question 39Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

During inspection, an installer finds thin, dark, parallel lines running along the busbars of several cells. These are identified as snail trails. What is the accepted cause?

  1. Corrosion of the aluminium frame
  2. Physical breakage of the cell fingers
  3. Reaction of silver paste with the encapsulant, often assisted by moisture and micro-cracks Correct answer.
  4. Overheating of the bypass diode in the junction box

Explanation

Snail trails are discolouration tracks caused by a chemical reaction involving the silver metallisation and the encapsulant, and they are commonly associated with micro-cracks that allow ingress. They are mainly cosmetic but indicate cell damage that should be monitored.

Question 40Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

Which factor best explains why monocrystalline modules usually have higher efficiency than polycrystalline modules of the same area?

  1. Mono modules contain more bypass diodes
  2. Mono wafers have fewer grain boundaries, so less carrier recombination occurs Correct answer.
  3. Mono modules are always manufactured with a thicker glass cover
  4. Mono cells use a different semiconductor with a wider band gap

Explanation

Both mono and poly cells use silicon, but mono wafers are a single crystal with no grain boundaries. Fewer defects at grain boundaries mean less recombination of charge carriers, giving higher efficiency and slightly better performance at higher temperatures.

Question 41Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module's datasheet gives a NOCT of 45 °C and a temperature coefficient of Pmax of -0.40 %/°C. At an ambient temperature of 35 °C with NOCT conditions, what is the approximate cell temperature?

  1. 45 °C
  2. 35 °C
  3. 80 °C
  4. 55 °C Correct answer.

Explanation

NOCT is defined as the cell temperature at 800 W/m² irradiance, 20 °C ambient and 1 m/s wind. For a rough estimate, the cell runs about NOCT minus 20 °C above ambient, so 35 °C ambient plus 25 °C rise gives about 55 °C.

Question 42Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A technician sees that a module's backsheet has turned brown and brittle over several years of operation. Which mechanism most likely explains this?

  1. Growth of the silicon crystal over time
  2. Reverse current flow through the module at night
  3. Mechanical load from wind exceeding the design limit
  4. Ultraviolet-induced degradation of the polymer backsheet Correct answer.

Explanation

Backsheets are polymer materials that can degrade under prolonged ultraviolet exposure and heat, becoming discoloured and brittle. This reduces insulation and mechanical protection, so affected modules should be assessed for safety and replaced if necessary.

Question 43Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

In a thin-film module, what is the purpose of the monolithic series interconnection created by scribing lines during manufacture?

  1. To connect individual cells in series on the same substrate without soldered ribbons Correct answer.
  2. To provide a mounting point for the frame
  3. To increase the physical thickness of the absorber
  4. To allow the module to be folded for transport

Explanation

Thin-film modules are built as a continuous stack, and laser or mechanical scribing divides the layer into cells that are then connected in series monolithically. This avoids the tabbing and stringing ribbons needed in crystalline modules and raises the module voltage.

Question 44Types of PV modules and cells: mono/poly/thin-film, module construction, ratings, datasheet interpretation, identification of defects

A module's datasheet states a maximum system voltage of 1000 V and a maximum series fuse rating of 15 A. What do these two values primarily govern?

  1. The colour and appearance of the module
  2. The number of modules that may be connected in series and the fuse size for string protection Correct answer.
  3. The tilt angle and azimuth of the array
  4. The encapsulant curing temperature during manufacture

Explanation

The maximum system voltage limits how many modules can be wired in series so that cold-condition Voc stays within the inverter and insulation rating. The maximum series fuse rating sets the largest overcurrent protection device permitted in the string.

Question 45Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

A household in a Punjab village runs four 9 W LED lamps for 5 hours per night and one 60 W fan for 6 hours per night. What is the daily energy demand of these loads?

  1. 540 Wh per day Correct answer.
  2. 420 Wh per day
  3. 240 Wh per day
  4. 660 Wh per day

Explanation

Energy equals power multiplied by hours of use, summed over all loads. The lamps draw 4 × 9 W × 5 h = 180 Wh and the fan draws 60 W × 6 h = 360 Wh, giving 540 Wh per day.

Question 46Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

For a solar home system, why is the inverter and wiring sizing based on the simultaneous peak load rather than on the total daily energy consumption?

  1. Because peak load decides the number of sunshine hours at the site
  2. Because daily energy consumption already includes all cable losses
  3. Because instantaneous current and apparent power determine conductor heating and inverter rating Correct answer.
  4. Because the inverter efficiency improves as the connected load rises

Explanation

Cables, switches and inverters must carry the current flowing at any instant, and heating depends on that current, not on the accumulated daily energy. Daily energy only sizes the array and battery, so peak simultaneous power is the correct basis for power-handling equipment.

Question 47Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

During a site survey a technician records the load list with a diversity (coincidence) factor. What is the purpose of applying this factor?

  1. To estimate the maximum load likely to be switched on at the same time Correct answer.
  2. To increase the battery capacity for cloudy days
  3. To correct the array output for module temperature
  4. To convert AC load watts into DC ampere-hours

Explanation

A diversity factor recognises that not every appliance in the list operates simultaneously, so the design peak is lower than the arithmetic sum. It is applied to the connected load to obtain a realistic maximum simultaneous demand for inverter and cable sizing.

Question 48Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

A module is mounted facing due south in Punjab at a tilt equal to the latitude. Which change would most reduce the annual energy yield at that site?

  1. Rotating the array to face due north Correct answer.
  2. Increasing the tilt by 5 degrees
  3. Raising the array height above the roof by 0.5 m
  4. Replacing the frame with a galvanised one

Explanation

Punjab lies in the northern hemisphere, where the sun's path is in the southern sky, so a north-facing array receives little direct beam radiation throughout the year. Tilt adjustments of a few degrees or mounting height changes affect yield only marginally.

Question 49Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

In Punjab, which fixed tilt angle is normally recommended for a year-round grid-connected rooftop array?

  1. Approximately the site latitude, near 30 degrees facing south Correct answer.
  2. Approximately 30 degrees facing west
  3. Zero degrees, with the modules laid flat
  4. Approximately 60 degrees facing south

Explanation

For a fixed annual installation, a tilt close to the local latitude gives a good compromise between summer and winter sun angles. Punjab lies near 30 degrees north, so a south-facing tilt of about 30 degrees is the usual starting recommendation.

Question 50Site survey and system sizing: load assessment, shading analysis, tilt and orientation, array and battery sizing, cable and inverter sizing

A technician uses a solar pathfinder or shading app at a proposed rooftop and finds a water tank shading the array between 09:00 and 10:30 in December. What is the correct design response?

  1. Ignore the shading because December output is not important
  2. Increase the battery bank to cover the shaded hours
  3. Reduce the tilt to zero so the shadow falls on the ground
  4. Relocate the array or lower the obstruction's shadow impact, since winter shading coincides with low sun angles Correct answer.

Explanation

Shading in winter matters most because the sun is low and the shadow is long, and a series string is limited by its worst-shaded module. Moving the array clear of the shadow or removing the obstruction preserves the yield that the string would otherwise lose.