ERAC ERAC Renewable Energy Systems & Technologies 1 — Questions and Answers
Question 1: What does the capacity factor of a solar photovoltaic (PV) system represent?
- The efficiency rating of individual solar panels
- The ratio of actual energy output to the maximum possible output over a period (Correct answer)
- The percentage of sunlight converted to electricity
- The installed capacity in kilowatts
Correct answer: The ratio of actual energy output to the maximum possible output over a period
Capacity factor is the ratio of actual energy generated to the maximum energy that could be generated if the system operated at full rated capacity continuously, typically 10–25% for US solar PV.
Question 2: Which US federal incentive provides a tax credit equal to a percentage of the cost of installing solar, wind, and other eligible renewable energy systems?
- Production Tax Credit (PTC)
- Investment Tax Credit (ITC) (Correct answer)
- Modified Accelerated Cost Recovery System (MACRS)
- Renewable Portfolio Standard (RPS)
Correct answer: Investment Tax Credit (ITC)
The Investment Tax Credit (ITC) under Section 48 of the Internal Revenue Code allows businesses to deduct a percentage of the cost of eligible renewable energy systems from federal taxes.
Question 3: In a wind energy assessment, what is the significance of the 'Weibull distribution'?
- It models electricity price fluctuations in wholesale markets
- It statistically describes the frequency distribution of wind speeds at a site (Correct answer)
- It calculates the structural load capacity of wind turbine towers
- It measures blade efficiency at varying angles of attack
Correct answer: It statistically describes the frequency distribution of wind speeds at a site
The Weibull distribution is a statistical model used to characterize wind speed variability at a site, which is essential for accurately estimating annual energy production from wind turbines.
Question 4: What is 'net metering' in the context of on-site renewable energy?
- Measuring net energy consumption after subtracting renewable generation
- A billing arrangement allowing excess renewable energy to be exported to the grid in exchange for credits (Correct answer)
- Installing separate meters for renewable and grid-supplied electricity
- A technique for optimizing battery storage charging schedules
Correct answer: A billing arrangement allowing excess renewable energy to be exported to the grid in exchange for credits
Net metering allows facilities with on-site renewable generation to export excess electricity to the utility grid in exchange for credits that offset future consumption charges.
Question 5: Which metric is most commonly used to evaluate the economic performance of a renewable energy project over its lifetime?
- Simple Payback Period
- Levelized Cost of Energy (LCOE) (Correct answer)
- Internal Rate of Return (IRR) only
- Net Present Value at year one
Correct answer: Levelized Cost of Energy (LCOE)
Levelized Cost of Energy (LCOE) represents the average cost per unit of electricity generated over a project's lifetime, accounting for capital costs, operating expenses, and total energy produced.
Question 6: In a geothermal heat pump system, what is the 'Coefficient of Performance' (COP) measuring?
- The ratio of ground temperature to ambient air temperature
- The ratio of heating or cooling output to electrical energy input (Correct answer)
- The percentage of ground loop fluid that is refrigerant
- The depth of borehole relative to building heating load
Correct answer: The ratio of heating or cooling output to electrical energy input
COP measures efficiency by expressing the ratio of useful thermal energy output (heating or cooling) to the electrical energy consumed by the heat pump compressor.
ERAC ERAC Renewable Energy Systems & Technologies 1
What does the capacity factor of a solar photovoltaic (PV) system represent?