Got Sun?
Go Solar
EXPANDED 2ND EDITION
Harness Nature’s Free Energy
to Heat and Power Your Grid-Tied Home
Rex A. Ewing and Doug Pratt
Contents
Introduction
The First Modern Solar Cell
7
Section One: Generating Electricity from the Sun and Wind
1
Why Would You Want A Solar / Wind Electric System?
12
Warm, Fuzzy Reasons for Renewable Energy | Hard-Edged
Financial Reasons
2
Is This Stuff Legal...or Safe?
17
Net Metering | Why Your Utility Company Doesn’t Want
Your Power | Technology Leads...and Regulations Follow
3
Riding Herd on Electrons: Electricity and Solar Cell Basics
25
Electrons Have All the Fun | Learning to Love Volts, Amps and
Watts | Falling Water and Electron Flow: A (Nearly) Perfect
Analogy | AC/DC: It’s More Than Rock ’n Roll | Solar Cells:
Teaching Old Electrons New Tricks | It’s Practically Efficient
4
You Want Batteries With That?
39
Direct Grid-Tie Systems (without batteries) | Battery-Based
Grid-Tie Systems | Which Is Right for Me?
5
Sizing Your Solar / Wind Electric System
47
Watt(s) You Use versus Watt(s) You Need | Sizing the
Components | How Many Batteries? | System Voltage
continued
iv
6
Where Does Everything Go?
55
Where Should I Put My Solar Array? | Making Space for the
Batteries, Inverters and Other Stuff | How Far Away Can It Be? |
Grid-Tie for the Cash- or Space-Challenged
7
Got Wind?
65
How Much Wind Is Enough? | Turbines: A Quick Look at the
Windy Beasts | Tower Styles and Options | Which System
Is Right for Me?
8
Let’s Talk Money and System Performance
77
Honest Cost Estimates and Real World Output for Solar/Wind
Electric Systems | System Monitoring
9
Any Financial Help Out There?
85
Federal / State / Local Sources | Return on Your Investment |
RE Credits or Green Tags
10
Permits and Paperwork
89
What To Expect, and Who Does It | Tell Your Friendly Local
Utility Company | Sell High, Buy Low (Time-of-Use Billing)
11
The Nuts and Bolts: What To Look For, What To Avoid
95
Solar Modules, Connections, Mounting Systems | Direct and
Battery-Based Grid-Tie Inverters | Safety Equipment |
Wind Turbines and Towers | Charge Controllers | Batteries
12
Who Does the Solar / Wind Electric Installation?
127
Finding and Qualifying a Contractor | Do It Yourself?
Guest Commentary by Christopher Freitas
131
continued
v
Section Two: Heating Your Home with Nature’s Free Energy
13
Using the Sun’s Warmth to Heat Your Home
134
Passive Solar Design Tips | Windows | Solar Air Panels
14
Get In Hot Water and Love It
141
How Solar Hot Water (Solar Thermal) Systems Work | Solar
Collectors | Sizing and Choosing the Best Type of System |
Circulating and Storing Hot Water | Other Considerations
15
Geothermal: Capturing the Heat Beneath Your Feet
159
How Geothermal Works | Types of Systems |
Size, Cost and Applicability
Postscript
165
Acknowledgments
167
Appendix
Tips on Appliances and Energy Conservation
Energy Consumption of Appliances
Wind Map (U.S.)
System Sizing Worksheet
Solar Irradiance U.S. Maps (June and December)
Solar Array Sizing Worksheet
State Energy Offices
Resources (manufacturers, organizations, education, etc.)
More Books and Reference Reading
Glossary
Index
Meet the Authors
vi
168
169
170
171
172
173
174
178
180
181
187
191
7
Introduction
H
ave you ever gotten so tired of waiting for
someone to do something for you that you
finally just did it yourself? That’s how most of
us learn to fix our bicycles when we’re kids:
we get fed-up waiting for some disinterested
adult—who will probably want an extortionary favor in return—to grudgingly agree
to adjust the brakes or patch a flat tire.
Exasperated, you march off to the garage, fish
around for a few tools, and get to work on the
problem. By the time the repair is done and
you’re glowing with a self-satisfied sense of
accomplishment, you realize it really wasn’t
all that difficult.
Sound familiar? Then this expanded 2nd
edition is for you. The air these days is
buzzing with talk of our expanding national
commitment to renewable energy, and we
applaud the government’s efforts that set a
more sustainable course for our country’s
energy future. But the only way to personally
be an active part of this green energy is to
make a resolution to wean your house or
condo (or, yes, even your apartment) from
the fossil-fuel cow. It’s not as hard as you may
think: with a bit of planning and a few components, you can convert your little corner of
the world into an environmentally responsible haven you can be duly proud of.
Today’s photovoltaic (solar-electric)
panels are cheaper, more efficient and versatile than they’ve ever been, and when combined with modern power inverters they will
generate electricity that is “clean” enough to
satisfy the persnickety needs of the most delicate electronics. Whether you want a large
array to run an entire house or one PV panel
for your apartment, solar electricity can be
configured to fit your needs.
Got wind? The noisy, awkward, breakdown-prone wind turbines of the past have
been replaced with quiet, highly efficient marvels of engineering that can produce useful
amounts of power in a gentle breeze. Many of
these new-generation wind turbines can be
directly tied into the power grid without the
need of batteries or charge controllers.
This is all really cool stuff that wasn’t available a few years ago, and it’s just waiting to be
installed on or near your home.
8
Do you like the idea of legally spinning
your electric meter backwards, and doing it
with a simple, non-polluting, silent power
source that will outlive your children? That’s
what solar energy can deliver right now, and
this book will explain your options. Solarelectric and wind systems deliver their energy
directly to your household, with any surplus
pushing out through your meter into the
grid. This is called utility intertie, or simply
grid-tie, and it’s legal in every state.
But solar- and wind-electric systems are
just the beginning. There is also solar hot
water to consider. It is, after all, an idea
that’s been in use since Roman times. And
if you watch with dismay as the rising price
of natural gas or electricity turn your
morning shower into an increasingly expensive proposition, you may want to consider
a solar hot water system for your domestic
hot water needs. There’s a system for practically every climate and budget, and unlike
the showy, clunky installations of the Carter
era, recent innovations in heat-collection
technology combine efficiency with class
and discreetness. Best of all, state and federal incentives for solar hot water systems
are also there for the taking.
But not all renewable energy comes
directly from the sky. Geothermal energy is
perhaps the most efficient and least under-
stood form of free and inexhaustible energy.
Modern ground-source heat-pump systems
are designed to extract the heat from the
ground beneath your feet so quietly and efficiently you’ll feel like you’re pilfering heat on
the sly. It’s the perfect hedge against rising
heating-fuel prices.
So what are you waiting for? Whether
you’re a trained electrician or plumber qualified to do the work yourself, or just a homeowner who believes that waiting until
tomorrow to make the world a better place is
not an option, you can use the information in
this book to help you decide which system or
systems will work best for you. We’ll even give
you tips on making the most of passive-solar
home design and also how to conserve energy
in your home to achieve the greatest impact
from nature’s free and renewable energy
sources. By the time you get around to finding
an installer, you’ll be on intimate terms with
your future system.
If you still need a little push, the federal
government and most states offer financial
incentives for those willing to invest in solar,
wind and geothermal energy, including tax
credits and substantial rebates. And should
you need financial assistance to get the process
kick-started, we’ll tell you how to go down that
road, too.
Let’s face it: you are all out of excuses.
9
Renewable energy is a proven technology that
is affordable and adaptable to almost any situation, and the financial incentives are about
as sweet as they can be. Whether you decide
to travel down the path to renewable energy
on an off-the-shelf Schwinn or a custombuilt Madone SSL by Trek, it’s going to be
your bicycle, so make the best of it. The wait
is finally over. ❖
The First Modern Solar Cell
It wasn’t exactly serendipity, which is, as they
gested that the idea of photovoltaics be
say, looking for a needle in a haystack and
explored.
finding instead the farmer’s daughter. No;
At that time, the only PV (solar) cells in
back in 1952, Daryl Chapin from Bell Labs
existence were made of selenium. Selenium
was definitely looking for the farmer’s
cells, however, could only produce about 5
daughter from the get-go. He just didn’t find
watts per square meter; a mere 0.5% converher in a haystack.
sion efficiency. Chapin wanted 6.0%—a
Here’s how it happened: Researchers at
twelve-fold increase in efficiency.
Bell labs, headed by Chapin, were trying to
As the gods of research would have it
find a way to operate Bell telephones in
play out, two of Chapin’s colleagues, Gerald
remote places, of which there was no dearth
Pearson and Calvin Fuller, were working in a
back then. Dry cell batteries were shortnearby lab with crystalline silicon in hopes of
lived, especially in hot, humid climes, so
building a solid-state rectifier, a device that
Chapin was searching for a more satisfactransforms AC to DC. But pure silicon is a
tory source of power. Wind was
not a very good conductor of
considered, along with thermoelectricity. Fuller, however, manelectric power and even steam
aged to improve its conductivity
engines. Chapin, being a solar
appreciably by introducing gallium
enthusiast (there was a great
into the crystal matrix. Then
deal of interest in passive solar
Pearson took it a step further; he
after World War II, due to a
gave the gallium-rich silicon a
worldwide fuel shortage), sug- Crystalline silicon solar cell. bath in hot lithium.
10
For whatever reason—scientists do so
love to play—Pearson shone a light on his
crystal and discovered that the light energy
induced an electric current. (He certainly
must have shouted something like “Eureka!”
at that point, though his exact words are lost
to history.) Pearson rushed to Chapin’s office
to announce the good news.
Though the first, crude silicon solar cell
was not capable of the 6% efficiency Chapin
was aiming for, it was far better than anything
he’d yet found. Chapin went to work to
improve it.The big breakthrough came when
Fuller vaporized phosphorus onto the surface
of a nascent solar cell. This brought the p-n
PV panels power the space station
Skylab (above) and an emergency
radio tower in remote mountains
(right). PHOTOS: NASA; SHELL SOLAR
junction (of which you will read more,
shortly) near the surface and, perhaps more
importantly, allowed for the deposition of
conducting channels to carry the lightinduced current away from the cell and into
an electrical circuit.
By 1954, Chapin, Pearson and Fuller had
produced a 6%-efficient solar cell and
announced it to the world. Much of this book
follows from their discoveries…
SOURCES: Solar Today (Jan/Feb 2004) “Good as Gold:
The Silicon Solar Cell Turns 50” by John Perlin,
Lawrence Kazmerski, Ph.D., and Susan Moon; and
www.eere.energy.gov/solar/solar_timeline.html.
In the late 1950s, solar cells were first used in space, and they
quickly became the most widely accepted energy source for
space applications. In 1964 NASA launched the first Nimbus
spacecraft – a satellite powered by a 470-watt PV array. Since
then, numerous craft have been launched, including Skylab and
the Mars Rover. Solar cells are used today to provide power for
remote telecommunications, signals and sensors, navigation aids,
water pumping, highway call boxes, off-grid lighting, calculators,
watches, portable electronics,
medical clinics, cathodic protection to prevent iron corrosion,
security lighting, billboards, and
emergency highway signage...
not to mention our homes and
offices.