Renewable Energy Systems Flashcards
7 cards from real Certified Energy Auditor Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Renewable Energy Systems flashcards as text
What does 'peak sun hours' mean as used in PV system sizing?
Answer: The equivalent number of hours per day with solar irradiance at exactly 1000 W/m²
Peak sun hours represent the equivalent number of hours per day that a location receives solar irradiance of 1000 W/m² (STC conditions), and are used to estimate daily PV energy production.
For a fixed-tilt PV installation in the continental US, what is the general rule for maximizing annual energy production?
Answer: Set tilt angle equal to local latitude, oriented toward true south
Setting the tilt angle equal to the local latitude and orienting panels toward true south maximizes annual solar energy capture for fixed installations in the Northern Hemisphere.
What is the typical annual degradation rate of crystalline silicon PV modules?
Answer: 0.5% per year
High-quality crystalline silicon PV modules typically degrade at approximately 0.5% per year, retaining about 80–87% of rated output at the end of a 25–40 year lifetime.
Which inverter technology is best suited for maximizing energy harvest when individual PV panels may experience partial shading?
Answer: Microinverter or DC power optimizer
Microinverters and DC optimizers perform maximum power point tracking (MPPT) at the individual panel level, preventing one shaded panel from degrading the output of the entire string.
A rooftop PV system is rated at 50 kW STC. Using a derate factor of 0.80 and 5 peak sun hours per day, what is the estimated daily energy production?
Answer: 200 kWh/day
Daily production = 50 kW × 0.80 derate factor × 5 peak sun hours = 200 kWh/day.
What is the primary function of a Maximum Power Point Tracker (MPPT) in a PV system?
Answer: To continuously adjust operating voltage to extract maximum power from PV panels
An MPPT continuously adjusts the electrical operating point of PV modules to ensure they operate at the voltage-current combination that produces maximum power under varying irradiance and temperature conditions.
In evaluating a solar thermal system for domestic hot water, what does the 'solar fraction' indicate?
Answer: The proportion of total hot water energy demand supplied by the solar thermal system
Solar fraction is the percentage of a building's total hot water (or space heating) energy demand provided by the solar thermal system, with the remainder supplied by a conventional backup source.