ICAR AIEEA-PG — Agricultural Engineering & Technology (Major Subject Group 10) · India · National Testing Agency for ICAR
Original practice questions written to the published syllabus · not past papersSolar thermal, solar PV, wind and micro-hydro for farms, from sun geometry to sizing a solar pump.
In the exams: GATE AG Section 3 (solar PV in 5 of 8, wind in 5 of 8 papers 2019–26); ICAR AIEEA-PG Unit V; ICAR AICE subject 42 Units 4, 5 and 7; NCEES PE energy sources
ICAR AIEEA-PG — Agricultural Engineering & Technology
Unit V 'renewable energy': definitions and principles — solar radiation instruments, flat-plate collector parts and efficiency, solar dryers, cookers, stills and water heaters, PV cell characteristics, wind turbine types and the Betz limit — with short calculations.
How our questions for ICAR AIEEA-PG spread across the units of Renewable Energy Sources (Solar, Wind). Difficulty: 31 easy, 43 medium, 0 hard.
| Measurement of solar radiation | 8 | |
| Solar dryers, cookers, water heaters and stills | 7 | |
| Photovoltaic cell physics and the I-V curve | 7 | |
| Solar radiation geometry | 6 | |
| Flat-plate collectors and their efficiency | 6 | |
| Fill factor and MPPT | 6 | |
| Energy storage | 6 | |
| Energy scenario | 5 | |
| Solar pumps and agri-voltaics | 5 | |
| Wind turbines and water-pumping windmills | 5 | |
| Concentrating collectors | 4 | |
| Power in the wind and the Betz limit | 4 | |
| Micro-hydro | 3 | |
| PV system sizing: on-grid and off-grid | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
One kilowatt-hour of energy is equal to:
B. 3.6 MJ
1 kWh = 1000 W × 3600 s = 3.6 × 10⁶ J = 3.6 MJ. 3.6 kJ is the energy of 1 W for an hour (1 Wh), a factor-of-1000 slip. 36 MJ is a factor-of-ten slip.
What is the air mass when the sun is at a zenith angle of 60°?
D. 2.0
Air mass m ≈ 1/cos θz = 1/cos 60° = 1/0.5 = 2.0. 0.5 is cos θz itself; 1.5 is the standard PV rating spectrum (θz ≈ 48°); 1.15 is 1/cos 30°, confusing zenith with altitude.
Anti-islanding protection in a grid-connected PV inverter:
B. Disconnects the inverter when the grid fails, so the system does not energise lines being repaired
An 'island' is a section of network kept live by local generators after the grid has gone down; it endangers line workers. Grid-tied inverters must shut down on loss of grid, which is why an ordinary on-grid system without battery backup gives no power in an outage.
In most farm solar pumping systems, energy for cloudy periods is stored mainly as:
C. Water in an elevated tank or reservoir
Storing water is far cheaper and longer-lived than storing electricity, so most solar pumps are battery-less and directly coupled through a controller, with a tank or the soil profile buffering supply.
The Betz limit, the maximum fraction of wind power that any open rotor can extract, is:
D. 16/27 ≈ 0.593
Momentum theory gives Cp = 4a(1 − a)², maximised at a = 1/3, where Cp = 16/27 ≈ 0.593. 2/3 is the velocity ratio at the rotor at that condition and 1/3 is the induction factor, not the power coefficient.
In a run-of-river micro-hydro scheme, the forebay is:
A. A tank at the penstock head that settles sediment and gives a steady water level at the penstock inlet
Water from the headrace enters the forebay, where sediment settles and a stable level prevents air being drawn into the penstock. The penstock is the pressure pipe, the tailrace returns water, and run-of-river schemes have no seasonal storage dam.
1000 m³ of water is pumped into a reservoir 50 m above the turbine. With a round-trip efficiency of 75%, how much electrical energy can be recovered?
C. 102.2 kWh
Stored energy = ρgVh = 1000 × 9.81 × 1000 × 50 = 490.5 MJ = 136.25 kWh. Recovered = 0.75 × 136.25 = 102.2 kWh. Ignoring efficiency gives 136.2; forgetting the water density (using volume as mass) gives 0.102 kWh. 181.7 kWh divides by the efficiency instead of multiplying.
Which of these concentrators is a line-focus system that uses rows of nearly flat mirror strips?
C. Linear Fresnel reflector
A linear Fresnel reflector approximates a trough with many flat or slightly curved strips focusing on a fixed linear receiver above them. Dishes and towers are point-focus; a CPC uses two parabolic segments, not flat strips.
The clearness index KT is defined as:
C. The ratio of global horizontal radiation to extraterrestrial horizontal radiation over the same period
KT = H/H0. It is used to correlate the diffuse fraction. n/N is the relative sunshine duration used in Ångström–Prescott, a different quantity.
In the perturb-and-observe MPPT method, if a small increase in operating voltage produces a decrease in array power, the controller should next:
D. Decrease the operating voltage
A power drop after a voltage increase means the operating point has passed the maximum and is on the right side of the peak, so the perturbation direction is reversed. The method then oscillates around the maximum power point.
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