Alternative Power (Workbook Questions) Flashcards
A photovoltaic cell or device converts sunlight to ____.
DC electrical energy
PV systems operating in parallel w/the electric utility system are commonly referred to as ____ systems.
interactive
PV systems operating independently of other power systems are commonly referred to as ____ systems.
stand-alone
While PV cells produce only ____ power, PV systems can produce ____ power.
DC/AC or DC
Compared to conventional power generating equipment, PV systems have relatively ____ life and require ____ maintenance.
long/low
A primary distinction between PV systems and fossil fueled power plants or engine generators is that PV systems ____.
convert a basic form of energy directly to electricity.
What are at least three limitations of PV systems?
- High Initial cost
- They require a relatively large area to produce a significant amount of power.
- lack of knowledge about solar.
What are the three main components of the electric utility system?
- Utility 2. Grid 3. Distribution
Solar power is commonly expressed in unites of ____.
watts per square meter or kilowatt-
Solar energy is commonly expressed in units of ____.
watts-hours per square meter or kilowatt-hours per square meter
The solar zenith angle is the angle between the ____.
sun and point in the sky directly overhead
The angle between the earth’s equatorial plane and line jointing the centers of the sun and the earth is called the ____.
solar declination
The apparent position of the sun with respect to an observer on earth at any given time of day is defined by its ____ and ____ angles.
solar altitude/solar azimuth
The orientation of PV arrays is defined by their ____ and _____ angles.
tilt/azimuth
For any location, which of these surfaces receives the greatest amount of annual solar radiation?
a. horizontal
b. south facing latitude tilt
c. single-axis tracking
d. dual axis tracking
Dual axis tracking
Global solar irradiance is measured with a ____.
pyranometer
A reference cell is essentially a ____.
photovoltaic device
A shadow band pyrometer measures what?
diffuse radiation
When working on low-slope roofs (pitch <= 4/12) with widths 50 feet or less, fall protection may be provided by:
- a warning line system and personal fall arrest system
- a warning line system and safety monitoring system
- the use of a safety monitoring system alone.
At most locations, a compass does not point true north due to ____.
magnetic delination
Hard shadows covering 10% of a PV array surface area can reduce output by as much as ____.
90%
What is the principal purpose for using a sun path calculator during a site survey?
To determine the extent of shading.
A PV system using multiple power sources (in addition to a PV array) is called a(n) ____ system.
hybrid
Which of these components are used in all PV systems?
energy storage, PV array, inverter
PV array
Inverters are used in PV systems to convert ____ power to ____ power.
DC/AC
Most interactive-only inverters use a(n) ____ as the input power source, while stand-alone inverters use a(n) ____as the input power source.
Utility/PV Array
A charge controller protects a battery from overcharge by regulating the ____ and/or ____ delivered to the battery from a PV array.
terminating/limiting
What is the principal reason for using energy storage in stand-alone PV systems?
To contain as much extra power as possible.
This photovoltaic effect involves the conversion of sunlight into what basic form of energy?
electricity
A photovoltaic cell consists of a junction between ____.
P-Type and N-Type semiconductor materials
The current output of a solar cell depends on the ____.
Area of the cell, temperature and irradiance, and operating voltage.
Dividing a larger solar cell into smaller pieces has what effect on the electrical output?
(voltage decreases and current increase) *confirm
What is the smallest field-installable unit in a photovoltaic system?
PV module
What are three factors that decrease lead-acid battery life?
- operating temp
- depth of discharge
- materials
List three factors that decrease the capacity of lead-acid cells.
- temperature
- discharge rate
- depth of discharge
Most battery charge controllers employed in PV systems use battery ____ to trigger charge control functions.
voltage
What are four steps in sizing stand-alone PV systems.
- battery bank
- load
- design
- PV array
Compared to a PV-only stand-alone system, hybrid systems can often be sized with a smaller ____ to meet a given system load.
battery - PV array
Why are larger PV modules (or panels) preferred over smaller ones for larger arrays.
Larger modules typically involve less installation cost, time, and labor.
A large PV array mounted in an open field is probably best installed using a(n) ____ mount.
rack
