Renewable Energy Systems

Question 1

A typical wind turbine has a sound pressure level of 38 decibels at a distance of how many metres?

Answer 1

500m

Question 2

Solar energy is captured and converted into two basic forms :

Answer 2

Thermal energy
Photovoltaic energy

Question 3

What are the four basic configurations used when designing a renewable energy system?

Answer 3

Stand-alone off-grid
Utility-interactive without batteries
Utility-interactive with batteries
A hybrid off-grid

Question 4

What type of system is often used a backup system to supply critical loads in the even the grid becomes unavailable?

Answer 4

Utility-interactive system with batteries

Question 5

What is the most complex system?

Answer 5

Hybrid off-grid:

Two or more energy sources in parallel, an array and wind turbine, both could supply dc to the inverter, and inverter supplies the load

Question 6

What parts of a wind turbine located in the nacelle (housing) ?

Answer 6

Shaft, gearbox and generator

Question 7

State some of the benefits of Annular Generator Technology:

Answer 7

Reduced transmission losses
The elimination of wear and tear of the gear box
The elimination of oil leakage

Question 8

What is an anemometer?

Answer 8

A wind meter

Question 9

Utility-interactive inverters can be classified as 5 different types:

Answer 9

String inverters
Central inverters
Utility-scale inverters
Multi-mode inverters
Module-level (microinverters)

Question 10

What is a charge controllers primary function?

Answer 10

Regulate the dc power to protect the battery bank from over-charging.

(regulate current to a trickle charge)

Question 11

Three main categories of wind systems:

Answer 11

Grid-connected systems without batteries
Grid-connected systems with batteries
Off-grid systems

Question 12

Define a dump load controller

Answer 12

Regulates output power of a micro-hydropower system by adjusting the amount of energy flowing into the ballast load to compensate for main load variations, such as stand-alone systems, and to prevent generator overvoltage.

Question 13

What’re the three main types of crystalline silicon solar cells?

Answer 13

Mono 12-16%
Multi or poly 8-11%
Amorphus 5-6%

Question 14

What is Solar cell efficiency?

Answer 14

The ratio of the electrical output of a solar cell to the incident energy in the form of sunlight

Question 15

What are the Standard Test Conditions of PV Systems?

Answer 15

Irradiance if 1000w/m
Solar spectrum of air mass (AM) 1.5
Cell or module temperature at 25 degrees

Question 16

Silicon is a shiny gray material that can act as a mirror by reflecting more than __% of the light that shines on it.

Answer 16

30%

Question 17

PV action could theoratically continue indefinitely if the cell is struck by light radiation from the sun. T or F?

Answer 17

True

Question 18

The process of converting photons to voltage is called:

Answer 18

Photovoltaic action

Question 19

Describe the relationship of voltage to the temperature of silicon.

Answer 19

Voltage is inversely proportional to the temp of silicon

Question 20

What determines the voltage of a PV cell?

Answer 20

The material of the cell
The cell temperature

Question 21

What does an MPPT circuit do?

Answer 21

Monitors array conditions (insolation, array temp)
Dynamically changes arrays resistance

Question 22

What is the heart of all PV systems?

Answer 22

The inverter

Question 23

A combination of the grid-tie and stand-alone inverter is called a __________

Answer 23

Bimodal inverter

Question 24

What two things does a microinverter add to a PV system?

Answer 24

Adds to overall cost
Adds flexibility

Question 25

Describe the two classes of dc-to-dc converters:

Answer 25

Boost converter- common to step up the voltage from a dc source
Buck converter- takes a high voltage from the dc source and bucks it down to a lower value