Renewable Energy Systems Flashcards
7 cards from real HERS 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 is the function of a 'maximum power point tracker' (MPPT) in a solar PV system?
Answer: It continuously adjusts electrical operating point to extract maximum power from the panels
MPPT algorithms dynamically adjust the load impedance seen by the PV array to keep it operating at the voltage/current combination that yields maximum power output.
In energy rating software, the acronym 'PVWatts' refers to which type of tool?
Answer: A NREL web-based tool that estimates solar PV energy production based on location and system parameters
PVWatts is NREL's free online tool that uses TMY weather data and user-entered system parameters to estimate annual electricity production from grid-connected PV systems.
Which factor most significantly reduces the efficiency of a crystalline silicon solar panel under real-world operating conditions compared to its STC rating?
Answer: Elevated panel operating temperature
Crystalline silicon panels lose approximately 0.3–0.5% efficiency per °C above 25°C (STC), and real operating temperatures often reach 45–65°C, causing significant power reduction.
A HERS rater is evaluating a solar thermal pool heating system. Which statement about these systems is correct?
Answer: They are generally unglazed collectors and operate at lower temperatures than DHW collectors
Solar pool heating collectors are typically unglazed polypropylene panels that operate at near-ambient temperatures, making them simpler and less expensive than glazed DHW collectors.
What is 'soiling loss' in the context of solar PV performance?
Answer: Reduction in energy output due to dust, dirt, pollen, or debris on panel surfaces
Soiling loss occurs when particulate matter accumulates on PV module surfaces, blocking incoming sunlight and reducing energy output, typically ranging from 1–5% in most US climates.
Which RESNET standard or guideline governs the rating of homes with on-site renewable energy generation systems?
Answer: RESNET/ICC 301
RESNET/ICC 301 is the Standard for the Calculation and Labeling of the Energy Performance of Dwelling and Sleeping Units using an Energy Rating Index, which governs how PV and other renewables are credited.
When documenting a solar PV system for a HERS rating, which piece of information is essential to verify the system meets the modeled specifications?
Answer: The system commissioning report or permit and interconnection agreement confirming rated capacity
A commissioning report or permit paired with the utility interconnection agreement confirms the installed system capacity and configuration match what was modeled in the energy rating.