Renewable Energy Systems MCQs 2026

Typical composition of usable biogas after cleaning is dominated by

1. A nitrogen only ✓
2. B sulfur hexafluoride ✓
3. C ozone ✓
4. D methane (CH4) ✓

Photovoltaic effect in a solar cell converts

1. A light energy directly into electrical energy via electron-hole pairs ✓
2. B heat into magnetic flux only ✓
3. C mechanical rotation into DC only ✓
4. D chemical fuel into AC only ✓

Open-circuit voltage Voc of a solar cell increases with

1. A higher irradiance and lower cell temperature ✓
2. B lower irradiance always ✓
3. C higher series resistance only ✓
4. D shorter wavelength only ✓

Short-circuit current Isc of a PV module is approximately proportional to

1. A module temperature only ✓
2. B incident solar irradiance ✓
3. C inverter efficiency only ✓
4. D grid frequency ✓

Maximum power point (MPP) of a PV array is the operating point where

1. A current is zero ✓
2. B voltage equals Voc ✓
3. C efficiency is always 50% ✓
4. D the product of voltage and current is maximum ✓

A maximum power point tracker (MPPT) in a solar inverter

1. A fixes voltage at Voc always ✓
2. B adjusts operating voltage to harvest maximum available power ✓
3. C disconnects the array at noon ✓
4. D replaces the need for DC wiring ✓

Fill factor of a solar cell is defined as

1. A Pmax divided by (Voc × Isc) ✓
2. B Isc divided by Voc ✓
3. C Voc divided by Isc only ✓
4. D series resistance times shunt conductance ✓

Series connection of identical PV modules increases

1. A total current while voltage stays fixed ✓
2. B total string voltage while current remains module current ✓
3. C both voltage and current equally ✓
4. D only temperature coefficient ✓

Parallel connection of PV strings increases

1. A total output current capability ✓
2. B open-circuit voltage of each module ✓
3. C only the fill factor ✓
4. D grid frequency ✓

Temperature coefficient of crystalline silicon PV power is typically

1. A negative — power falls as cell temperature rises ✓
2. B positive at all temperatures ✓
3. C zero regardless of irradiance ✓
4. D infinite at MPP ✓

Bypass diodes in a PV module string are used to

1. A increase Voc during full sun only ✓
2. B allow current around shaded or faulty sub-strings ✓
3. C convert AC to DC ✓
4. D replace the inverter ✓

Gasification of biomass converts solid fuel into

1. A only liquid diesel without processing ✓
2. B AC power directly ✓
3. C only inert nitrogen ✓
4. D syngas (CO + H2 mixture) ✓

Combined heat and power (CHP) from biomass improves overall efficiency by

1. A rejecting all heat to atmosphere ✓
2. B operating only at night ✓
3. C using waste heat from electricity generation ✓
4. D eliminating the steam cycle ✓

Energy density of dry wood biomass is roughly

1. A an order of magnitude lower than coal on mass basis ✓
2. B equal to uranium fuel pellets ✓
3. C higher than natural gas per kg ✓
4. D zero because it is renewable ✓

Sustainable biomass harvesting requires

1. A clear-cutting faster than regrowth always ✓
2. B regrowth rate at least matching extraction rate ✓
3. C no consideration of land use ✓
4. D exclusive use of fossil backup ✓

Cofiring biomass with coal in power plants

1. A reduces net fossil CO2 emissions per MWh ✓
2. B eliminates the need for mills ✓
3. C requires no boiler modification ever ✓
4. D prevents ash production ✓

Bagasse from sugar mills in Pakistan is commonly used for

1. A nuclear fuel fabrication ✓
2. B cogeneration of steam and electricity in the sugar industry ✓
3. C HVDC transmission only ✓
4. D insulator manufacturing ✓

Moisture content in biomass fuel strongly affects

1. A only generator frequency ✓
2. B net calorific value and combustion stability ✓
3. C only corona onset voltage ✓
4. D only transformer turns ratio ✓

Bioethanol produced from fermentable sugars is primarily used as

1. A transport fuel blend component ✓
2. B grid-scale HVDC coolant ✓
3. C transformer oil substitute ✓
4. D cable insulation ✓

Biodiesel is commonly produced from

1. A transesterification of vegetable oils or animal fats ✓
2. B coal gasification only ✓
3. C uranium enrichment ✓
4. D wind pitch control ✓

Carbon neutrality claim for sustainably managed biomass assumes

1. A zero CO2 is ever emitted ✓
2. B regrown vegetation re-absorbs CO2 released on combustion timescale ✓
3. C fossil carbon is added permanently ✓
4. D no land-use impact ✓

Primary air pollutant concern from poorly controlled biomass combustion is

1. A only helium inert gas ✓
2. B ozone depletion by CFCs from wood ✓
3. C SF6 leakage ✓
4. D particulate matter and CO ✓

Alternative and Renewable Energy (ARE) policy framework in Pakistan is overseen by

1. A NEPRA alone without policy role ✓
2. B WAPDA as sole renewable regulator ✓
3. C PTA telecommunications authority ✓
4. D AEDB (Alternative Energy Development Board) ✓

NEPRA in Pakistan primarily regulates

1. A telecom spectrum only ✓
2. B electric power tariffs and licensing of generation and distribution ✓
3. C nuclear weapons policy ✓
4. D agricultural water pricing only ✓

Renewable energy policy in Pakistan has targeted substantial share of generation from

1. A only imported coal long-term ✓
2. B only diesel gensets ✓
3. C hydro, wind and solar resources ✓
4. D only nuclear exclusively by 2030 ✓

Quaid-e-Azam Solar Park is located in

1. A Karachi harbour only ✓
2. B Punjab (Bahawalpur region) ✓
3. C Gilgit-Baltistan glaciers ✓
4. D Islamabad metropolitan only ✓

Jhimpir and Gharo wind corridors in Sindh are developed for

1. A coal seam gasification only ✓
2. B offshore tidal barrages only ✓
3. C nuclear desalination only ✓
4. D utility-scale wind power generation ✓

Net metering regulations in Pakistan allow eligible consumers to

1. A sell power only to foreign grids ✓
2. B bypass NEPRA completely ✓
3. C offset consumption with on-site renewable export to the distribution grid ✓
4. D operate without any meter ✓

Upfront tariff and competitive bidding mechanisms for renewables in Pakistan are approved by

1. A individual DISCOs without oversight ✓
2. B customs authority only ✓
3. C NEPRA based on government policy guidelines ✓
4. D provincial police ✓

Wheeling charges in power sector refer to

1. A fees for using the transmission network to move power ✓
2. B solar module import duty only ✓
3. C wind turbine blade pitch cost ✓
4. D biogas digester maintenance only ✓

Must-run status for renewable generators typically means

1. A unlimited export without any curtailment ever ✓
2. B no grid connection required ✓
3. C exemption from all safety codes ✓
4. D dispatch priority or minimum dispatch subject to grid security ✓

Indigenous hydro potential in Pakistan is concentrated mainly in

1. A Thar desert only ✓
2. B Arabian Sea offshore only ✓
3. C northern river systems and existing dam cascades ✓
4. D urban load centres only ✓

Solar irradiance in southern Pakistan (Sindh/Balochistan) is generally

1. A too low for any PV use ✓
2. B equal to polar regions ✓
3. C among the highest in the country, favourable for PV ✓
4. D blocked year-round by monsoon only ✓

Anaerobic digestion of organic waste produces

1. A biogas rich in methane ✓
2. B pure oxygen ✓
3. C only solid ash without gas ✓
4. D photovoltaic electrons ✓

Grid-tied solar inverter must synchronize with the utility by matching

1. A only DC bus voltage ✓
2. B only rotor speed ✓
3. C only transformer tap position ✓
4. D voltage magnitude, frequency and phase sequence ✓

Anti-islanding protection in grid-connected PV prevents

1. A MPPT operation during full sun ✓
2. B use of bypass diodes ✓
3. C continued energization of a de-energized utility section ✓
4. D series string wiring ✓

Standard Test Conditions (STC) for PV modules specify

1. A 1000 W/m² irradiance, 25°C cell temperature, AM1.5 spectrum ✓
2. B 500 W/m² and 50°C always ✓
3. C 800 W/m² and 0°C only ✓
4. D irradiance independent of spectrum ✓

Conversion efficiency of a commercial silicon PV module is typically in the range of

1. A 60 to 80 percent ✓
2. B 15 to 22 percent ✓
3. C 1 to 2 percent ✓
4. D 90 to 95 percent ✓

Thin-film PV technologies such as CdTe or CIGS compared with mono-Si often show

1. A always higher efficiency than best silicon ✓
2. B lower cost per watt and better high-temperature performance in some designs ✓
3. C no need for encapsulation ✓
4. D operation only at night ✓

Betz limit states the maximum theoretical power coefficient Cp for an ideal wind turbine is approximately

1. A 0.593 or 16/27 ✓
2. B 0.25 ✓
3. C 1.0 ✓
4. D 0.95 ✓

Power in the wind is proportional to

1. A wind speed only ✓
2. B square of air density only ✓
3. C air density, swept area and cube of wind speed ✓
4. D blade pitch angle only ✓

Cut-in wind speed of a turbine is the speed at which

1. A the turbine is shut down for maintenance ✓
2. B rated power is reached ✓
3. C yaw control is disabled ✓
4. D the generator begins producing usable power ✓

Rated wind speed is where the turbine

1. A stops permanently ✓
2. B operates at cut-in only ✓
3. C reaches its nameplate electrical power output ✓
4. D has zero tip speed ratio ✓

Variable-speed wind turbines use power electronics to

1. A run at fixed synchronous speed only ✓
2. B eliminate the need for a gearbox always ✓
3. C operate without any generator ✓
4. D optimize aerodynamic efficiency and reduce mechanical stress ✓

Doubly-fed induction generator (DFIG) in wind applications allows

1. A partial-rated converter control of rotor power ✓
2. B full power through the stator converter only ✓
3. C DC output without inverter ✓
4. D operation without any slip ✓

Tip speed ratio (TSR) in wind turbines is

1. A ratio of hub height to diameter only ✓
2. B gearbox ratio times slip ✓
3. C ratio of blade tip speed to wind speed ✓
4. D cut-in divided by cut-out speed ✓

Pitch control on large wind turbines adjusts blade angle to

1. A increase torque at cut-in only ✓
2. B replace the yaw drive ✓
3. C eliminate the need for a tower ✓
4. D limit power and speed above rated wind conditions ✓

Yaw control aligns the nacelle so that

1. A the blades are vertical to the ground always ✓
2. B the gearbox is bypassed ✓
3. C the transformer is star-delta only ✓
4. D the rotor faces the prevailing wind direction ✓

Power curve of a wind turbine plots

1. A voltage versus current only ✓
2. B blade mass versus height ✓
3. C electrical output versus wind speed ✓
4. D frequency versus slip only ✓

Offshore wind farms compared with onshore typically have

1. A lower wind speeds always ✓
2. B no need for subsea cables ✓
3. C higher capacity factors and higher installation cost ✓
4. D zero maintenance requirements ✓

Induction generator connected to the grid without a converter requires

1. A operation at exactly synchronous speed ✓
2. B reactive power support and speed slightly above synchronous ✓
3. C only DC excitation ✓
4. D no slip ✓

Wake effect behind a wind turbine causes

1. A higher wind speed downstream always ✓
2. B elimination of cut-out speed ✓
3. C reduced wind speed and increased turbulence for downstream turbines ✓
4. D increased air density ✓

Capacity factor of a wind farm is

1. A rated power divided by cut-in speed ✓
2. B actual energy output divided by output if running at rated power continuously ✓
3. C blade length divided by hub height ✓
4. D number of turbines times Betz limit ✓

Vertical-axis wind turbines (VAWT) differ from horizontal-axis designs in that

1. A they always exceed HAWT efficiency ✓
2. B they require no tower ✓
3. C they cannot be grid-connected ✓
4. D the rotor axis is perpendicular to the wind stream ✓

Biomass energy is derived from

1. A organic matter such as wood, crop residue and biogas feedstock ✓
2. B uranium fission only ✓
3. C tidal motion only ✓
4. D geothermal heat of the core only ✓

Direct combustion of biomass in a boiler produces

1. A DC electricity without any turbine ✓
2. B nuclear moderation ✓
3. C only hydrogen without combustion ✓
4. D heat for steam generation or process use ✓

Renewable IPPs in Pakistan commonly sell power under

1. A barter without contracts ✓
2. B only spot gasoline pricing ✓
3. C international postal treaties ✓
4. D power purchase agreements with DISCOs or bulk consumers ✓

Grid integration challenge for high renewable penetration in Pakistan includes

1. A excess synchronous inertia always ✓
2. B too much baseload hydro only ✓
3. C variability of wind/solar and transmission constraints ✓
4. D absence of any load centres ✓

AEDB facilitation includes support for

1. A replacing NEPRA tariff role entirely ✓
2. B project approvals, incentives and renewable resource assessment ✓
3. C operating all DISCOs directly ✓
4. D manufacturing nuclear fuel ✓

Clean Development Mechanism (CDM) era projects in Pakistan renewables aimed at

1. A eliminating all grid codes ✓
2. B banning private generation ✓
3. C carbon credit revenue alongside electricity sales ✓
4. D removing environmental review ✓