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solar energy Flashcards

1
Q

what is electromagnetic radiation in more simple terms

A

light

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2
Q

what percentage of energy from the sun is visible light

A

45%

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3
Q

what wave length is visible light

A

400-700 nm

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4
Q

list these from largest wave length to smallest: Microwave, X-ray, visible, radio, infrared, UV, gamma ray

A

radio, microwave, infrared, visible, UV, X-ray, Gamma ray

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5
Q

As wavelength decreases, frequency… and energy….

A

increases
increases

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6
Q

what does quantum theory consider about photons

A

quantum theory considers the radiation as a stream of particles called photons with zero rest mass and energy quantum

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7
Q

Irradiance is what kind of density?

A

power

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8
Q

irradiation is what kind of density

A

energy

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9
Q

what is the solar constant

A

the irradiance on a surface that faces the sun and is just outside earths atmosphere
1360 W/m^2

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10
Q

What is irradiation also called when dealing with solar energy

A

insolation

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11
Q

what does a pyranometer do

A

measure global and diffuse radiation

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12
Q

what is used to calculate diffuse radiation

A

a shading ring

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13
Q

what does a pyrheliometer do

A

measure direct solar radiation that falls on the detector

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14
Q

How many AU are between the sun and the earth

A

1.0
their orbit distance

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15
Q

what is the earths obliquity/rotational axis

A

23.45 degrees

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16
Q

what is the earths obliquity/rotational axis measured from

A

a line perpendicular to the orbital plane around the sun

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17
Q

the tilt of the earth creates variation in what

A

the seasons

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18
Q

what are the two types of motion between the sun and the earth

A

revolution and rotation

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19
Q

describe the earths revolution

A

elliptic plane around the sun - a year

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20
Q

describe the earths rotation

A

around polar axis - a day

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21
Q

the earth revolves around the sun in elliptical path with small eccentricity what does this mean

A

the sun-earth distance varies, and radiation is inversely proportional to the square of the distance between the distance

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22
Q

define AM

A

air mass: ratio of the path traveled by the rays through the atmosphere to the vertical distance. (thickness of the atmosphere)

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23
Q

where would i find the zenith angle

A

its the angle between the the local vertical and the line from the observer to the sun. Off the edge of the atmosphere.

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24
Q

where would I find the latitude

A

angle of location on earth w.r.t. equatorial plane surface azimuth. Its from the center of the earth and connects to the atmosphere to create the zenith

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25
where would I find the surface azimuth
angle measured clockwise from the north. makes the zenith angle be in 3D
26
The suns position is characterized by X and E, which is a function of
the local time of day, t the day of the year, d the latitude of the observer, lambda
27
AM =
h/l = 1/cos(x)
28
what two conditions are necessary to have a solar radiation flux reaching the surface of 1000W/m^2
AM1.5 and sun at about 48 degrees from overhead position
29
does the sun appear higher in the sky during summer or winter
summer
30
how can i determine the declination angle
joining the center of the sun and the earth w.r.t. equatorial plane
31
what does the nautical almanac describe
the position of a selection of celestial bodies for the purpose of enabling navigators to use celestial navigation to determine the position of their ship while at sea. It finds the solar declination and you only need to input the day of the year
32
if im in the northern hemisphere, where would I want my passive solar buildings to face
south
33
reduction or elimination of _______ facing windows will reduce heat loses
poleward the sun rises in the east, sets in the west
34
what are 2 more passive solar heating techniques from the slides
shrubs and trees to increase shading on the house. Natural ventilation moves fresh air around the building
35
what is passive solar heating
direct use of sunlight to heat buildings
36
what is active solar heating
gathering of solar energy by collectors
37
what is the typical active solar collector
a liquid is heated by the sun as it flows through the solar collector, then pumped through heat exchangers, creating hot water for the building
38
what are the 5 types of active solar collectors
solar architecture, flat collectors, evacuated tubes, concentrators, solar ponds
39
what is a type of solar collector and what does it consider
trombe wall: exposure control, circulation, insulation, thermal energy storage
40
what kind of light do flat collectors work with
direct and diffused light
41
how to flat collectors work
black tubes containing water and heated by the sun
42
what are flat collectors useful for
ambient heating, domestic hot water systems, and swimming pools
43
describe evacuated tubes
a thick glass outer tube and a thinner glass inner tube, The tubes are made of borosilicate or soda lime glass, which is strong, resistant to high temperatures and has a high transmittance for solar irradiation. vacuum is established between the two cylinders, reducing the convection heat losses. Hot vapor rises to top of heat pipe. Heat transfer from heat tube to system fluid. multiple rows of parallel, transparent glass tubes supported on a frame
44
how do concentrators work
the suns energy is concentrated onto a boiler using a heliostat. the water becomes a vapor powering a turbine and then generator. the water is the condensed and cooled and a pump sends it back up to the boiler
45
how does a solar pond work
surface water has a low density. Bottom, saturated salt water has a high density and therefore holds up to 90 C of heat.
46
advantages of harnessing solar ponds for energy
low temp operation, high thermal mass(no fluctuations for day and night), cost effectiveness(low invest), and large heat reservoir
47
describe solar thermal energy conversion
light to heat conversion KE of electrons gets converted into heat energy
48
describe principle of solar PV energy conversion
light to photo-voltage conversion separation of opposite charges results in electric potential difference
49
describe microwave and infrared energy radiation
< 1,5 eV to generate atom bond rotation, torsion, and vibration
50
describe visible energy radiation
< 3.5 eV excites electrons to higher energy levels
51
describe UV and x-ray radiation
> 3.5 eV causes ionization of atoms
52
describe the pros and cons of crystalline material types
monocrystalline: good efficiency, but expensive. polycrystalline: cheaper but less efficient
53
crystalline material is most commonly
silicon
54
describe the amorphous thin films
doesn't need special crystal vibrations in order to absorb light, it has a direct band gap much less expensive and can be flexible sheets
55
rank these from strongest to least strong absorption: monocrystalline, polycrystalline, amorphous thin films
amorphous thin films, monocrystalline, polycrystalline
56
why can organic polymers become the best solution for PV
low cost, light weight, flexibility, less toxic than inorganic materials, and can be an organic-inorganic combination
57
what do semiconductors do
use their electrical properties to convert photon energy into electricity
58
photovoltaic effect
semiconductors absorb light and excite electrons, creating electron-hole pairs. They can be separated and directed to create an electric current
59
band gap
energy difference between the valence bond and the conduction band. The band gap allows absorption of the solar spectrum while minimizing energy loss
60
terms: valence band, conduction band definitions: where electrons move freely, where electrons are bound
valence band: where electrons are bound conduction band: where electrons move freely,
61
efficiency
balance efficiency and cost - silicon
62
stability and longevity
silicon can withstand environmental conditions and are ideal to use long-term
63
rank these from largest band gap to smallest: semiconductor, insulator, and conductor
insulator, semiconductor, conductor
64
define doping
intentional introduction of impurities into an intrinsic semiconductor
65
what is a low/light doping
one dopant atom is added per 100 million atoms
66
what is a high/heavy doping
one per ten thousand atoms
67
define these as intrinsic and extrinsic: P-type, N-type, pure silicon
intrinsic: pure silicon extrinsic: P-type and N-type
68
a P-type would have what kind of atom and characteristic
boron or gallium atom (3VE) void/hole
69
a N-type would have what kind of atom and characteristic
phosphorous or arsenic atom (5VE) and an extra VE freely moving around
70
P-type has what kind of charge
positive
71
N-type has what kind of charge
negative
72
A minute amount of either N-type or P-type doping turns a silicon crystal from a good ________ into a viable (but not great) ____________, named “semiconductor”
insulator conductor
73
P-N junction: electrons more abundant in the ________, tend to diffuse to the ________
n-side p-side
74
P-N junction: holes in the _______ tend to diffuse to the ________
p-side n-side
75
P-N junction: the net effect of these diffusions is that the n-side becomes _________ and the p-side becomes ________
positive negative
76
parallel: currents ___, voltages _____. this is a solar _____
add constant array
77
series: currents _____, voltages_____. this is a solar ______
constant add panel
78
the connection between the voltage across an electrical device and the current through it can be represented by
an I-V curve
79
the IV curve simply represents all of the possible operating points that a PV device could be at for a given set of test conditions, i.e., a given
irradiance temperature, and spectrum
80
Short circuit current, Isc
max current from a solar cell, the PV device would operate at if a zero resistance load or near zero resistance load was affixed to the PV device. So it's the highest current with zero voltage
81
Open circuit voltage, Voc
where the PV device would operate if you attached a load with very high or near infinite resistance. It's the point with the highest voltage at zero current
82
max power point, MPP
the max power point is of utmost interest to us because it ultimately is the numerator in our efficiency equation
83
an IV curve assess
performance in real time
84
By analyzing the I-V curve, technicians can assess the solar panels'
health, detect any degradation in power output, and identify any issues such as shading, damage, or faulty components
85
the four steps to measure the IV curve of a solar cell
set up the test environment connect the IV curve tracer(vary load), record the data, analyze the results
86
By increasing the resistive load on a solar cell continuously from zero (short circuit) to a very high value (equivalent to open circuit) one can determine the
maximum power point.
87
Plotting the power as a function of the voltage finds the ____________ is the peak point of the power curve
Pmpp, maximum power point
88
solar cell efficiency is equal to
power out/ power in
89
standard test conditions
1000 W/m^2, 25C or 77 F, AM1.5 sunlight

ENER 305 (9 decks)

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