FIRST
This billionaire genius built a high-tech suit of armor after being kidnapped.
Tony Stark
What type of electricity is produced by a photovoltaic module?
- AC
- DC
- AC and DC simultaneously
- The module does not produce electricity
DC
Photovoltaic (PV) modules, commonly called solar panels, produce direct current (DC) electricity when sunlight strikes their solar cells.
DC electricity flows in one direction, while alternating current (AC) periodically reverses direction.
Most homes use AC electricity, so solar systems commonly use an inverter to convert the DC electricity into usable AC electricity.
Think of a solar panel like a battery in terms of the type of electricity it supplies. Both provide DC electricity, although a solar panel generates electricity from sunlight while a battery stores chemical energy.
In a typical grid-connected solar PV system with a string inverter, which component converts DC electricity from the solar modules into AC electricity?
- Revenue-grade meter
- Junction box
- Inverter
- AC disconnect
Inverter
An inverter converts direct current (DC) electricity produced by solar panels into alternating current (AC) electricity.
Solar panels naturally produce DC electricity, but most homes and businesses use AC electricity.
Think of the inverter as a translator. Solar panels speak DC, but your house speaks AC. The inverter translates the electricity into a form the house can use.
This special serum transformed Steve Rogers into a super soldier.
Super Soldier Serum
Power surges can add to the fundamental frequency to produce distorted waveforms.
True or False
True
Electrical power normally follows a smooth AC sine wave. Electrical disturbances can cause that waveform to become distorted.
A power surge is a sudden increase in voltage that can temporarily disturb the normal electrical waveform.
However, there is an important distinction:
Power surges: Sudden increases in voltage.
Harmonics: Additional frequency components that combine with the fundamental frequency and distort the waveform.
Imagine a smooth ocean wave. A sudden splash disrupts its shape. Similarly, electrical disturbances can disrupt a smooth electrical waveform.
Batteries are divided into classes based on their applications and their discharge and cycle characteristics.
True or False
Batteries are classified according to how they are designed to be used.
Two common categories are:
Starting batteries: Designed to deliver a large amount of current for a short period, such as starting a vehicle.
Deep-cycle batteries: Designed to repeatedly discharge and recharge, making them suitable for many solar energy storage applications.
A car battery delivers a large burst of power to start an engine. A deep-cycle solar battery is designed to supply electricity over longer periods and be recharged repeatedly.
This fictional African nation is home to Black Panther and the powerful metal Vibranium.
Wakanda
What is the primary purpose of a revenue-grade production meter in a solar PV installation?
- Convert DC electricity into AC electricity
- Measure the electrical energy produced by the PV system to a specified accuracy
- Disconnect the solar array during a utility outage
- Protect rooftop wiring from rain
Measure the electrical energy produced by the PV system to a specified accuracy
A revenue-grade production meter accurately measures how much electrical energy a solar system generates.
Electricity production is typically measured in kilowatt-hours (kWh).
These meters are designed to meet specified accuracy standards and may be used for billing, incentive programs, or production verification.
Think of a production meter like an odometer in a car. An odometer tracks how many miles you've driven, while a production meter tracks how many kilowatt-hours your solar system has generated.
A technician turns off the AC disconnect for a solar PV system. Which statement is correct?
- Every conductor in the PV system is now guaranteed to be deenergized.
- The solar modules immediately stop producing voltage whenever sunlight reaches them.
- Illuminated PV modules may still produce hazardous DC voltage.
- The revenue-grade meter automatically removes all hazardous electrical energy.
Illuminated PV modules may still produce hazardous DC voltage.
Turning off the AC disconnect does not automatically eliminate all electrical hazards in a solar PV system.
Solar panels can continue generating DC voltage whenever sufficient sunlight reaches them.
Even if the inverter is turned off or disconnected from the utility, portions of the DC wiring may remain energized.
Imagine turning off the AC disconnect on a rooftop solar system at noon. The solar panels are still exposed to sunlight, so they may continue producing hazardous DC voltage.
These special particles allow Ant-Man to shrink or grow in size.
Pym Particles
System requirements and characteristics of battery types must be considered when choosing a battery.
True or False
Not every battery is suitable for every solar installation.
When selecting a battery, electricians and system designers must consider:
Voltage: Must be compatible with the system.
Capacity: Determines how much energy can be stored.
Battery chemistry: Different types have different performance and safety characteristics.
Cycle life: How many times the battery can be charged and discharged.
Temperature requirements: Batteries have specific operating temperature limits.
Cost and maintenance: Some batteries require more maintenance than others.
A homeowner who wants backup electricity during a power outage needs a battery system capable of supplying the required electrical loads for the desired number of hours.
What is the main purpose of racking in a solar PV installation?
- Convert electrical energy into sunlight
- Increase the frequency of AC electricity
- Support and secure PV modules
- Store electricity for later use
Support and secure PV modules
Racking is the mounting structure used to hold solar panels securely in place.
Solar racking systems can be installed on rooftops, on the ground, or on other suitable structures.
The racking system helps:
Keep solar panels securely attached.
Position panels at the required angle and orientation.
Withstand environmental forces such as wind and snow loads.
Maintain proper spacing and support for the panels.
Think of solar racking like the frame of a house. Just as a house needs a strong structure to support its roof, solar panels need a secure mounting system to hold them in position.
This actor portrays Spider-Man in the Marvel Cinematic Universe.
Tom Holland
This mystical artifact allows its user to manipulate time. (The necklace that holds the "Time Stone")
Eye of Agamotto
Transformers use induced ____________ to transfer AC power from one circuit to another while transforming the power to higher or lower voltages or providing electrical isolation.
Magnetic Fields
Transformers use electromagnetic induction to transfer electrical energy between circuits.
When alternating current flows through the primary winding, it produces a changing magnetic field.
That changing magnetic field induces voltage in the secondary winding.
Transformers can be used to:
Step up voltage: Increase voltage.
Step down voltage: Decrease voltage.
Provide electrical isolation: Separate circuits electrically while transferring energy magnetically.
A transformer can take 480 volts AC and step it down to 120 volts AC for equipment that requires a lower voltage.
Higher temperatures and slower discharge rates result in increased battery capacity.
True or False
True
Battery capacity refers to how much electrical energy a battery can store and deliver.
Two factors that affect battery capacity are:
Temperature: Warmer temperatures can temporarily increase the available capacity of certain batteries, especially lead-acid batteries.
Discharge rate: When a battery releases energy more slowly, it can often deliver more total amp-hours before reaching its cutoff voltage.
Imagine two identical lead-acid batteries. One powers a small light for several hours, while the other powers a large motor that draws electricity very quickly. The battery powering the small light may deliver more total amp-hours because it is discharging more slowly.
What is the basic purpose of an inverter in a grid-connected PV system?
- Convert DC electricity into AC electricity
- Secure solar modules to a roof
- Store electrical energy for nighttime use
- Convert sunlight directly into DC electricity
Convert DC electricity into AC electricity
An inverter converts DC electricity generated by solar panels into AC electricity that can power a home or be delivered to the electrical grid.
In a grid-connected system, the inverter also synchronizes its AC output with the utility grid's voltage and frequency.
Imagine installing solar panels on a house. The panels generate DC electricity, but household receptacles supply AC electricity. The inverter converts the DC electricity into AC electricity that household appliances can use.
This talking raccoon is known for his love of weapons and explosives.
Rocket Racoon
This Avenger sacrificed herself on Vormir so Hawkeye could obtain the Soul Stone.
Black Widow
This former Air Force pilot gained cosmic powers and became one of the MCU's strongest heroes.
Carol Danvers
Captain Marvel
This magical hammer can only be lifted by those deemed worthy.
Mjolnir
This villain collected all six Infinity Stones to eliminate half of all life in the universe.
Thanos
An electrical enclosure will be installed outdoors where it may be exposed to rain. What should be considered when selecting the enclosure?
- Only its color and appearance
- Whether it is the least expensive available enclosure
- Whether it has enough room, regardless of its environmental rating
- Whether its enclosure type and equipment instructions make it suitable for the location
Whether its enclosure type and equipment instructions make it suitable for the location
Electrical enclosures protect electrical equipment from environmental conditions such as rain, dust, and moisture.
Different enclosure ratings are designed for different environments.
Common examples include:
NEMA 1: Generally intended for indoor use.
NEMA 3R: Commonly used outdoors to provide protection against falling rain and other specified conditions.
NEMA 4: Provides additional protection against water exposure, including hose-directed water.
NEMA 4X: Similar to NEMA 4, with additional corrosion resistance.
You wouldn't install a regular indoor electrical panel outside in the rain. You need an enclosure designed and rated for outdoor conditions.
A building's electrical panel has no unused breaker spaces. Which statement about installing tandem breakers is correct?
- Tandem breakers may be used only where the panel and applicable requirements permit them.
- Tandem breakers are always permitted when installing solar equipment.
- Any two existing breakers can be replaced with a tandem breaker.
- Installing tandem breakers automatically increases the panel's electrical capacity.
Tandem breakers may be used only where the panel and applicable requirements permit them.
A tandem breaker contains two individual circuit breakers that fit into one panel space.
However, not every electrical panel allows tandem breakers.
Before installing one, electricians must verify that the panel is listed and labeled for the specific tandem breaker and its intended position.
A tandem breaker does not increase the electrical capacity of the panel.
Imagine an electrical panel with every breaker space occupied. You cannot automatically install tandem breakers to create more room. You must first check the manufacturer's panel labeling to determine whether they are permitted.
Inverters are available in many different configurations and ratings.
True or False
Solar inverters come in different sizes and configurations depending on the electrical system they serve.
Common types include:
String inverters: Convert DC electricity from a group of solar panels into AC electricity.
Microinverters: Typically installed at individual solar panels to convert DC into AC.
Hybrid inverters: Can manage solar production and compatible battery storage.
Off-grid inverters: Supply AC electricity to systems operating independently of the utility grid.
Inverters also have different power, voltage, and current ratings.
A small residential solar installation might use a 5-kW inverter, while a large commercial installation might require multiple much larger inverters.