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