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Solar Power
• Passive solar for homes
• Heat water for homes
• Photovoltaic(PV) cells
• Concentrated solar power
Unit 13 – Solar Power - Slide 1
Unit 13 – Solar Power - Slide 2
First, an
introductory
calculation…..
Curved Earth
~1000W/m2
250W/m2
Unit 13 – Solar Power - Slide 3
0 W/m2
Round Numbers
Unit 13 – Solar Energy - Slide 4
• Around 1350 watts of solar hits a square
meter of upper atmosphere above equator
• Around 30% is reflected by clouds and
atmosphere so around 1000 watts of solar
hits a square meter of earth at equator
• Earth is curved so on average 250 watts of
solar hits a square meter of earth
• 1.2 X 1017 Watts of solar power hits the
earth’s surface.
• Total power used ~ 1.6 X 1013 Watts
Round Numbers
Unit 12 – Energy from the earth - Slide 5
• 1.2 X 1017 Watts of solar power hits the
earth’s surface
• Around 29% of the earths surface is land
• 3.5 X 1016 Watt
• Around 33% of that is desert
• 1.1 X 1016 Watt
• We collect that energy with 10% efficiency
• 1.1 X 1015 Watt
• Earth’s average power usage is 1.6X1013 Watt
• Over 70 times the requirement
Passive Solar Heating
Unit 13 – Solar Power - Slide 6
• Four parts
- Large south-facing windows
- High R-value insulation
- Distribution method
- Thermal mass
• Inexpensive and simple.
• Tough to retrofit.
• Best to put in original
home design.
• Sun changes angle with season.
Unit 13 – Solar Power - Slide 7
Solar Hot Water Heating
Unit 12 – Energy from the earth - Slide 8
Solar Hot Water Heating
Unit 13 – Solar Power - Slide 9
Photovoltaic (PV) Cells
Unit 13 – Solar Power - Slide 10
P-type semi-conductor
Unit 13 – Solar Power - Slide 11
Silicon crystal Silicon crystal
“doped” with boron
Si B
Outer shell
electron
N-type semi-conductor
Unit 13 – Solar Power - Slide 12
Silicon crystal Silicon crystal “doped”
with Phosphorus
Si P
PN Junction
Unit 13 – Solar Power - Slide 13
N type P type
+
+
+
+
+
-
-
-
-
-
Electric
Field
Photovoltaic(PV) cell
Unit 13 – Solar Power - Slide 14
N type P type
Electric
Field
+-
PV Cells
Unit 13 – Solar Power - Slide 15
~12% to 20% efficient
Expensive up-front
Tough to compare to cost from
utility
Creates DC current. Inverter
changes to AC and syncs with
grid
Most common for home is grid-
connected
Consumption vs Renewable Production
Unit 07 Electricity - Slide 16
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
Naperville Use
Carter Production
Naperville Power Consumption and
Carter Solar Panel Production
14 June 2017
MegaW
att
Kilo
Watts
Better method
Unit 12 – Energy from the earth - Slide 17
My home uses about 20kW-hours of electricity
every day in the summer. Let’s say I wanted to
get my electricity from solar panels and those
solar panels were about 15% efficient.
My house is in a shady area so it only gets half
(50%) of all the sun that hits the ground.
How many square meters of solar panels would
I have to put on my roof? My roof has about
240 square meters on it. Is this most of my
roof? A little of my roof?
Cost of system ~ $15,000After Federal Rebate $10,000
Energy Produced in 2018: 4960kWh
Saving of ~$600 per year. SREC payment per year ~$420
Break Even: 13 years1
Pay off period
1Assuming 3% discount rate
Solar in Arizona
Unit 13 – Solar Power - Slide 19
Using the insolation value for
Tucson on our formula sheet,
estimate the how much of the
state of Arizona would have to
be covered with solar cells in
order to provide all of the
electrical power used in the US.
Tengger Desert Solar Park - China
Unit 13 – Solar Power - Slide 20
43,000,000 m2
~1.5GW
Impossible?
Datong Solar Power - China
Unit 13 – Solar Power - Slide 21
• 1000 MW (Phase 1)
Better method
Unit 12 – Energy from the earth - Slide 22
My home uses about 20kW-hours of electricity
every day in the summer. Let’s say I wanted to
get my electricity from solar panels and those
solar panels were about 15% efficient.
My house is in a shady area so it only gets half
(50%) of all the sun that hits the ground.
How many square meters of solar panels would
I have to put on my roof? My roof has about
240 square meters on it. Is this most of my
roof? A little of my roof?
Concentrated Solar
Unit 13 – Solar Power - Slide 23
Largest Commercial Power from Solar in 2015
Unit 12 – Energy from the earth - Slide 24
Semasolar in Seville Spain - 19MW
Unit 13 – Solar Power - Slide 25
2,650 heliostats
Ivanpah in Mojave Desert
Unit 13 – Solar Power - Slide 26
(Design 392 MW , 4000 Acres)
Unit 13 – Solar Power - Slide 27
173,500heliostats
Concentrated Solar
Unit 13 – Solar Energy- Slide 28
• Creats electricity for grid same a coal
• Built in energy storage system
• “Dispatchable” (as opposed to
“intermittent”)
• Uses water in dry/hot areas
• )
How much comes from renewables?
Unit 13 – Solar Energy- Slide 29
Solar?
Unit 13 – Solar Energy- Slide 30
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