HERS Renewable Energy Systems 2 — Questions and Answers
Question 1: Which solar panel configuration allows individual panels to operate independently, minimizing the impact of shading on the overall system output?
- String inverter configuration
- Microinverter or DC optimizer configuration (Correct answer)
- Central inverter configuration
- Series-wired configuration
Correct answer: Microinverter or DC optimizer configuration
Microinverters and DC optimizers allow each panel to operate at its maximum power point independently, so shading on one panel does not drag down the entire string.
Question 2: In a grid-tied solar PV system, what happens to electricity production during a utility grid outage without battery backup?
- The system continues producing power at full capacity
- The system automatically switches to off-grid mode
- The system shuts down to prevent islanding hazards (Correct answer)
- The system reduces output to 50% to protect the grid
Correct answer: The system shuts down to prevent islanding hazards
Grid-tied inverters are required by code to shut down during grid outages to prevent islanding, which could endanger utility workers.
Question 3: What is the primary purpose of a solar site assessment tool like a Solar Pathfinder or Solmetric SunEye?
- Measuring panel efficiency under lab conditions
- Evaluating shading impacts and solar access at a specific location (Correct answer)
- Calculating inverter sizing requirements
- Determining optimal tilt angle for fixed-mount arrays
Correct answer: Evaluating shading impacts and solar access at a specific location
These tools map the sun's path and identify obstructions that cast shadows, allowing raters to quantify solar access and expected energy production.
Question 4: According to RESNET standards, what solar production data source is commonly used to model PV output in energy rating software?
- ASHRAE Fundamentals Handbook
- TMY (Typical Meteorological Year) weather data (Correct answer)
- IECC climate zone tables
- DOE Building Energy Data Book
Correct answer: TMY (Typical Meteorological Year) weather data
TMY data provides hourly weather data representative of long-term average conditions and is the standard input for solar energy production modeling.
Question 5: When calculating the HERS Index for a home with a solar PV system, how is on-site renewable generation typically credited?
- It reduces the rated home's energy loads directly
- It is not credited in the HERS Index calculation
- It offsets site energy use, reducing the HERS score (Correct answer)
- It only counts if the system is battery-backed
Correct answer: It offsets site energy use, reducing the HERS score
Under RESNET standards, PV generation offsets the home's site energy consumption and is credited when calculating the HERS Index.
Question 6: What does the term 'tilt angle' refer to in a solar PV installation?
- The angle between the panel surface and vertical
- The angle between the panel surface and horizontal ground (Correct answer)
- The compass direction the panels face
- The angle of the roof rafter from the ridge
Correct answer: The angle between the panel surface and horizontal ground
Tilt angle is measured from horizontal (0° = flat, 90° = vertical) and affects how directly sunlight strikes the panel surface throughout the year.
Question 7: Which renewable energy system type generates electricity from heat produced by a temperature differential between a fluid and its surroundings?
- Photovoltaic (PV) systems
- Solar thermal collectors
- Thermoelectric generators (Correct answer)
- Geothermal heat pump systems
Correct answer: Thermoelectric generators
Thermoelectric generators convert heat differentials directly into electricity using the Seebeck effect, unlike PV which uses photons or heat pumps which move heat.
HERS Renewable Energy Systems 2
Which solar panel configuration allows individual panels to operate independently, minimizing the impact of shading on the overall system output?