For detailed tour information,
go to nationalsolartour.org.
A S E S N AT I O N A L S O L A R TO U R
WELCOME
Find a Local Tour Near You
The ASES National Solar Tour is held in most neighborhoods in October, but tours can
be organized any time of year. See tour listings at nationalsolartour.org.
See Solar in Your Neighborhood
A
merican Solar Energy Society (ASES) is taking it to the
streets with our flagship event, the National Solar Tour.
Thanks for going on tour with us! Let’s be part of the solution!
This year marks our 20th annual tour, and we have extended
the tour thoughout the entire month of October. The US
Department of Energy also designates October as Energy
Awareness month. The National Solar Tour is the world’s largest
grassroots solar movement — where homes, businesses,
schools, religious meeting centers, and other organizations
across the country open their doors and roofs to neighbors who
are looking to learn more about how they can utilize renewable
energy in their own lives and communities.
This year’s National Solar Tour highlights many unique
renewable energy features, net zero homes and other notable
sights. Just in time for the Pope’s visit, a Franciscan monastary
in Elicott City, MD will be showing off their solar panels and rain
garden. Louisville, KY is proud to show an early adopter of solar
with a PV system over 20 years old. Ohio is boasting 118 tours
sites. PepCo, a Washington DC area utility, purchased the 2011
Solar Decathlon winner “Watershed” and is in use for learning
purposes, including the National Solar Tour, complete with two
electric vehicles. Many homes have a trifecta of clean energyfor example PV, geothermal, and electric vehicle. What’s your
trifecta? Grey water re-use? Rainwater harvesting? Composting
toilet?
While most tours are part of a local tour, there are also several
single site tours this year. For example, a home in Lake Hughes,
By CARLY RIXHAM
CA, of the Antelope Valley, will be showing a wide variety of
energy efficiency including a ground source heat pump. A
woman in Raliegh, NC will be showing (and selling!) her home
that she retrofitted with solar after surviving the 9-11 tragedy
and leaving New York.
The premise of the tour is to get neighbors talking about local
incentives, local installers/contractors, local laws. Ask your
neighbors about their monthly utility bills. Learn how much you
can save while you help the planet. Research the options and
discover your neighborhood’s best-kept solar secrets! Find out
about the return on your investment with solar thermal, or solar
electric options for zero money down in over 20 states. Learn
about sustainability, and best of all, get to know your neighbors!
From grassroots to grasstops, we can work together to be
stewards of the planet. But we must act with haste. If you are
thinking of going solar, now is the time. The 30% Investment
Tax Credit is set to expire for residential at the end of 2016. That
means by December 31, 2016, your system must
be turned on in order to receive the credit. I have
a vision of 100 percent renewables by 2050. We
could do it now! We have already reached grid
parity in 10 states.
Let’s start a conversation in our own backyard.
Special thanks to hundreds of volunteers who
organize local tours. Collectively, you are the
National Solar Tour!
2015 SPONSOR
AM E RICAN
S O LA R
E N E R GY SOCI ETY
American Solar Energy Society
Programs
Executive Director
ASES National Solar Tour
ases.org/tour
Editorial Elaine Hebert elaine@norcalsolar.org and
SOLAR TODAY magazine
solartoday.org
Advertising
ASES National Solar Conference,
SOLAR 2015 ases.org/conference
carly rixham crixham@ases.org
Paulette middleton paulette@panaramapathways.net
720-420-7937
carly rixham crixham@ases.org
SOLAR TODAY (ISSN: 1042-0630)
is published eight times a year by the
American Solar Energy Society,
2525 Arapahoe Ave, Suite E4-254,
Boulder, Colorado 80302, 303.443.3130,
info@ases.org, ases.org. Copyright © 2015
by the American Solar Energy Society Inc.
All rights reserved.
ON THE COVER: Dani and Coby Russo proudly show off their 10.4 KW installation on a New York solar tour. Photo courtesy of
Raina Russo, Women4Solar.
2
A SES NATIONAL S O L A R TO U R nationalsolartour.org
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
AM E RICAN
S O LA R
E N E R GY SOCI ETY
get involved: locate an ASES chapter in your community
Alabama
Alabama Solar Assoc.
P: 256.658.5189
morton@al-solar.org
al-solar.org
Contact: A. Morton
Archibald Jr.
Arizona
Arizona Solar Energy Assoc.
P: 602.952.8192
j2envarch@aol.com
arizonasolarenergy.org
Contact: Daniel Aiello
Arkansas
Arkansas Renewable Energy Assoc.
P: 877.575.0379
info@arkansasrenewable
energyassoc.org
arkansasrenewableenergyassoc.org
Contact: Frank Kelly
California
NorCal Solar Energy Assoc.
P: 510.545.4925
info@norcalsolar.org
norcalsolar.org
Contact: J.P. Ouellette
Orange County Renewable Energy Society
P: 714.794.7795
plesniak@gmail.com
ocrenewables.org
Contact: Adam Plesniak
Solar Living Assoc.
P: 707.472.2456
karen.kallen@solarliving.org
solarliving.org
Contact: Karen Kallen
San Diego Renewable Energy Society
chair@sdres.org
sdres.org
Contact: Stephen Johnston
Colorado
Colorado Renewable Energy Society
P: 720.231.5317
info@cres-energy.org
cres-energy.org
Contact: Alex Blackmer
Connecticut
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Delaware
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Florida
Florida Renewable Energy Assoc.
P: 407.710.8705
info@cleanenergyflorida.org
cleanenergyflorida.org
Contact: Bob Stonerock
Midwest Renewable Energy Assoc.
P: 715.592.6595
dougs@midwestrenew.org
midwestrenew.org
Contact: Doug Stingle
Indiana
Indiana Renewable Energy Assoc.
317.635.1701
info@indianarenew.org
indianarenew.org
Contact: Laura Arnold
Iowa
Midwest Renewable Energy Assoc.
P: 715.592.6595
dougs@midwestrenew.org
midwestrenew.org
Contact: Doug Stingle
Kansas
Heartland Renewable Energy Society
P: 913.299.4474
info@heartland
renewable.org
heartlandrenewable.org
Contact: Craig Wolfe
Kentucky
Kentucky Solar Energy Society
P: 908.963.1619
wjbarnett@ieee.org
kyses.org
Contact: Jack Barnett
Louisiana
Louisiana Solar Energy Society
membership@lses.org
lses.org
Contact: Jeff Shaw
Maine
Maine Solar Energy Assoc.
P: 207.497.2204
sunwatt@juno.com
mainesolar.org
Contact: Richard Komp
Maryland
Mid Atlantic Solar Energy Society
P: 301.880.7045
john.essig@mases.org
mases.org
Contact: John Essig
Massachusetts
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Michigan
Great Lakes Renewable Energy Assoc.
P: 269.384.9915
glrea.info@gmail.com
glrea.org
Contact: Del Bachert
Midwest Renewable Energy Assoc.
P: 715.592.6595
dougs@midwestrenew.org
midwestrenew.org
Contact: Doug Stingle
Georgia
Georgia Solar Energy Assoc.
P: 404.522.4775
norene.quinn@gasolar.org
gasolar.org
Contact: Norene Quinn
Minnesota
Minnesota Renewable Energy Society
P: 612.963.4757
laurac@mnrenewables.org
mnrenewables.org
Contact: Laura Cina
Idaho
Idaho Renewable Energy Assoc.
P: 208.629.6858
mikecmedberry@msn.com
Contact: Mike Medberry
Mississippi
Mississippi Solar Energy Society
sdlewis@megagate.com
Contact: Steve Lewis
Illinois
Illinois Solar Energy Assoc.
P: 312. 376.8245
lesley.mccain@illinoissolar.org
illinoissolar.org
Contact: Lesley McCain
Missouri
Heartland Renewable Energy Society
P: 913.299.4474
info@heartland
renewable.org
heartlandrenewable.org
Contact: Craig Wolfe
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
Nevada
Solar NV
P: 702.507.0093
vegassolarguy@gmail.com
solarnv.org
Contact: Guy Snow
Utah
Utah Solar Energy Assoc.
P: 801.566.5620
ebishop@utsolar.org
utsolar.org
Contact: Elias Bishop
New Hampshire
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Vermont
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
New Jersey
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Virginia
Mid Atlantic Solar Energy Society
P: 301.880.7045
john.essig@mases.org
mases.org
Contact: John Essig
New Mexico
New Mexico Solar Energy Assoc.
info@nmsea.org
nmsea.org
Contact: Gary Vaughn
Washington
Solar Washington
P: 425.270.5612
jim@solarwa.org
solarwa.org
Contact: Jim Avery
New York
New York Solar Energy Society
P: 917.974.4606
wyldon1@gmail.com
nyses.org
Contact: Wyldon Fishman
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
North Carolina
North Carolina Sustainable Energy Assoc.
P: 919.832.7601
kathleen@energync.org
energync.org
Contact: Kathleen Fleming
Ohio
Green Energy Ohio
P: 614.985.6131
bill@greenenergyohio.org
greenenergyohio.org
Contact: William A. Spratley
Oregon
Solar Oregon
P: 503.231.5662
claire@solaroregon.org
solaroregon.org
Contact: Claire Carlson
Pennsylvania
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
Rhode Island
Northeast Sustainable Energy Assoc.
P: 413.774.6051
nesea@nesea.org
nesea.org
Contact: Jennifer Marrapese
South Carolina
South Carolina Solar Council
info@scsolarcouncil.org
scsolarcouncil.org
Contact: Bruce Wood
Tennessee
Tenneessee Solar Energy Assoc.
P: 865.974.9218
steve@tnsolarenergy.org
tnsolarenergy.org
Contact: Steven Levy
Texas
Texas Solar Energy Society
P: 512.751.1873
800.465.5049
info@txses.org
txses.org
Contact: Lucy Stolzenburg
Washington, D.C.
Mid Atlantic Solar Energy Society
P: 301.880.7045
john.essig@mases.org
mases.org
Contact: John Essig
Wisconsin
Midwest Renewable Energy Assoc.
P: 715.592.6595
dougs@midwestrenew.org
midwestrenew.org
Contact: Doug Stingle
STUDENT CHAPTERS
Appalachian State University
Sustainable Energy Society
asuses@gmail.com
asuses.appstate.edu
Contact: Tess Scanlon
Austin Community College
Renewable Energy Student Assoc.
scott.moser@g.austincc.edu
austincc.edu/resa
Contact: Scott Moser
Colorado State University
P: 970.491.3784
marclively34@gmail.com
Contact: Markus Lively
NCSU Renewable Energy Society
P: 919.515.9782
ccmaurer@unity.ncsu.edu
Contact: C.C. Maurer
Penn State Student Chapter of ASES
clubs.psu/up/ases
ases@psu.edu
Contact: Jeffrey Brownson
Shoreline Community College
Student Chapter of ASES
debstecher@msn.com
thecommunitysolarproject.org
Contact: Debbie Stecher
Solar Education & Outreach,
The Ohio State University
P: 614.595.3847
searles.31@buckeyemail.osu.edu
seo.org.ohio-state.edu
Contact: Trace Searles
University of Florida
P: 954.673.8797
ases.uf@gmail.com
ufases.org
Contact: Jason Rosen
Key
Green = This chapter has sub-chapters. Visit
online to find the sub-chapter nearest you.
nationalsolartour.org A S E S N AT I O N A L SOL AR TOUR
3
Leasing vs. Owning Solar Electric PV
Home Solar Panels: Pros, Cons, and Hidden Costs
by Graham Shorr
S
olar energy has hit the mainstream. Once limited to
consumers with deep pockets and strong environmentalist
values, solar panels are less expensive than ever and are saving
customers huge amounts of money per year.1 As a result, solar
has a fast-growing appeal among middle-class Americans. But if
you’re considering making the solar switch, how will you pay for
the equipment? Who installs the panels, and under what terms?
There are two ways to switch to solar panels for your home–
leasing or buying. Each option has unique advantages and
disadvantages, not to mention short and long-term financial implications. We’ll examine the options, and help you understand
what’s best for your budget and electricity needs.
Leasing Solar Panels
According to the Solar Energy Industries Association (SEIA),
solar energy now powers more than 600,000 US homes.2 Every
three minutes, another home makes the switch to solar. That
kind of growth is substantial, but many solar enthusiasts don’t
own the panels on their rooftops. They lease them.
Pros of Leasing
Leases allow to you go solar even if you don’t have thousands
of dollars for a down payment. While leasing won’t allow you
to maximize energy savings when you switch to solar (for that,
you’ll have to buy your panels), it can still significantly lower
your monthly energy costs. The advantages of leasing include:
Low-cost financing: Leasing lets you put solar panels on
your home and start saving right away, usually for $0 down. Instead of paying your local utility company for power, you’ll just
pay the solar panel leasing company to use the system.
Multiple financing options: Depending on your circumstances, you can usually choose a solar lease or a power purchase
agreement (PPA).3 With a solar lease, you only pay the leasing
company for the solar equipment; you can use as much energy
as you please. On the other hand, a PPA lets you pay for the
power you consume at a set price per kilowatt hour. With a PPA,
monthly fees account for the power itself, not the equipment.
Maintenance and repairs: Since you don’t own the panels,
you don’t have to fix them when they break! The leasing company will handle all solar panel maintenance and repairs.
Option to purchase: At the end of your lease, you can
purchase the solar energy system at a depreciated market value
or, sometimes at a discounted price,4 depending on the terms of
your lease.
Lower energy costs: Leasing home solar panels is not like
leasing a car, which usually results in overpaying for use of the
4
A SES NATIONAL S O L A R TO U R nationalsolartour.org
vehicle. If you live in a state where solar energy is at least as
cheap as the grid,5 you’re likely to enjoy equal or lower monthly
energy costs even though you’re leasing a system from someone
else. You can use the solar energy cost calculator from the Institute for Local Self-Reliance to estimate your saving.
Cons of Leasing
While leasing might be ideal for some buyers, it isn’t right for
everyone. As a lessee, you will have to reconcile the benefits of
leasing with:
Contractual terms: Solar leases or PPAs typically last 20
years – sometimes longer.6 On one hand, two decades is a long
time. On the other hand, many utility companies already enjoy a
local monopoly, which is tantamount to a lifetime “contract.”
No tax benefits: Owning your own solar panels usually
qualifies you for various tax credits and rebates (more on those
in a bit). If you lease your system, the leasing company gets to
enjoy those benefits – not you.
Lack of ownership: Those solar panels aren’t yours, they
belong to somebody else. To many homeowners, not having
control over equipment that lives on top of their homes simply
isn’t appealing.
In most cases, these disadvantages shouldn’t discourage you
from switching to solar. You’ll likely save on current monthly
electric bill, and can always purchase the panels later if you
want.
Hidden Costs of Leasing
As with most home improvement efforts, leasing solar panels
isn’t free from obscure or unexpected costs. Even if things appear straightforward and you like what you’re hearing from the
leasing company, keep the following possibilities in mind and
mitigate them by performing due diligence:
Insurance premiums: Depending on your homeowners
insurance policy, installing solar panels on your roof could leave
you with a higher premium. By the same token, solar panels
could lower your premium, but you should talk with your insurance provider before committing to a lease.
Roof damage and rebuilding: Solar panels are mounted to
your roof, and there’s a chance they will damage it. Be sure your
lease specifies who is responsible for damage to the roof and
who will cover any necessary rebuilding or restoration.7 If you’re
responsible for those costs, you need to know about it.
Remember, you’re about to make a serious modification to
your home. Checking with your insurance company and understanding your lease are part of your homework. “Hidden” costs
won’t be hidden if you’re aware of them!
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
Buying Solar Panels
In a sense, solar panels are the same thing today that they were
ten years ago: an investment. The difference is thanks to lower
costs, they now can quickly deliver a positive return. Unfortunately, solar panels have five figure price tags before rebates or
tax incentives. Though much more affordable than a few years
ago, the price of solar panels still puts them out of reach for many
would-be cash buyers, hence the popularity of leasing.
Pros of Buying
Why purchase your own solar panels? The answer is simple:
more money in your pocket. Invest in solar panels today, and you
will reap financial rewards in the future:
Tax credits and rebates: The federal government and most
states will help you pay for green energy! In addition to the Residential Renewable Energy Tax Credit,8 which covers up to 30%
of costs, all 50 states offer incentives to leave the grid. To see how
your state helps cover solar panel costs, refer to the North Carolina Clean Energy Technology Center’s database of state incentives
for solar and other renewable energies.
Free energy… eventually: To oversimplify a complex process,
solar panels can pay for themselves.9 The length of time it takes for
that to happen depends on your energy use and how much you
pay for your solar energy system, but the fact remains that you
will recoup your investment – and probably much more! Excess
electricity is sold back to utility companies by what is known as
net metering where the utility installs a bi-directional meter that
records power bought by a customer and then subtracts the excess
power generated and pushed back into the grid by the customer.
Solar Renewable Energy Credits (SRECs): some states,10 you
can sell unused energy generated by your solar panels back to the
utility companies in the form of SRECs. Instead of paying your
local utility for power, they’ll be sending you checks!
Resale value: Buyers tend to pay more for houses fitted with
solar panels.11 Go solar, and you may increase your home’s value.
By now may be thinking, “Leasing sounds good, but buying
seems even better.” With so many reasons to buy solar panels,
why would anybody lease? Unfortunately, there are some risks to
purchasing your own system.
Cons of Buying
Buying solar panels has never been more affordable, but that
doesn’t make it affordable for everyone. Consider these risk to
buying your own system:
Time: Those positive returns on your solar investment don’t
arrive overnight. For some buyers, it takes around 10 years.4 If
your state doesn’t provide many incentives, or you’re unable to sell
SRECs, it may take even longer.
Maintenance and replacement: Solar panels won’t last forever,
and they could need maintenance between now and when they
fail. If you own solar panels, you’ll be on the hook for all those
repairs. How long will your system last? Most manufacturers offer
warranties of 20 to 25 years for solar panels and 10 years for solar
inverters.12
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
Ultimately, the disadvantages of buying solar panels are similar
to the disadvantages of other investments with high up-front
costs. To get in the game, you have to part with a lot of cash and
wait several years for the return.
Hidden Costs of Buying
Wondering what else you’ll have to pay for when you purchase
solar panels? Here are some potential hidden costs:
Expiring tax incentives: Solar tax credits may not last forever.13 As residential solar becomes cheaper and more popular, it’s
probable many states – and possibly the federal government – will
reduce or eliminate incentives for going solar.
Installation: Don’t forget to calculate installation charges into
your up-front solar energy system costs. Grid-tie and off-grid systems have different installation costs,14 so you need to understand
what you’re buying and how much you can expect to pay. As with
leased systems, additional hidden costs include the potential for
roof damage and higher insurance premiums.
Conclusion
Rooftop solar panels have a bright future. Fossil fuel prices tend
to increase over time, but the price of solar energy is rapidly falling. That’s because solar energy isn’t a fuel – it’s a technology that’s
becoming ever more efficient.15
Whether you buy or lease home solar panels, you’ll be taking advantage of that efficiency. Just be sure you understand the
advantages and disadvantages of each choice so you can make the
most financially responsible decision. When you’ve decided to
lease or buy, contact a professional who can explain the next steps.
You’ll need to determine whether your roof can accommodate
the panels and compare bids from different installers or leasing
companies.
1. http://www.npr.org/2015/04/10/398704224/how-solar-power-has-gotten-so-cheap-sofast/
2. http://www.seia.org/news/united-states-installs-1354-mw-solar-q3-2014
3. http://www.epa.gov/greenpower/buygp/solarpower.htm
4. http://www.npr.org/2015/02/10/384958332/the-great-solar-panel-debate-to-lease-or-tobuy
5. http://www.ucsusa.org/our-work/clean-energy/increase-renewable-energy/affordablerooftop-solar-united-states#.VUyq1dNVhBd
6. https://www.energysage.com/solar/financing/should-you-buy-or-lease-your-solar-panelsystem
7. http://www.nola.com/business/baton-rouge/index.ssf/2015/04/solar_power_system_
scams_attorney_general_buddy_caldwell.html
8. http://energy.gov/savings/residential-renewable-energy-tax-credit
9. http://www.improvenet.com/a/solar-roi
10. http://www.greentechmedia.com/research/srec-market-monitor
11. http://www.nytimes.com/2015/02/22/realestate/solar-panels-and-home-values.
html?_r=0
12. http://solarenergy.net/solar-power-resources/10-things-to-know-before-going-solar/
13. http://www.nytimes.com/2015/01/26/business/worry-for-solar-projects-after-end-oftax-credits.html
14. http://www.solarpanelscostguide.com/#versus
15. http://www.bloomberg.com/news/articles/2014-10-29/while-you-were-getting-workedup-over-oil-prices-this-just-happened-to-solar
Thanks to expertise.com for permission to use this article.
nationalsolartour.org A S E S N AT I O N A L SOL AR TOUR
5
BA S ICS
Energy-Efficiency Basics
Solar Water-Heating Basics
By Seth Masia and Carly Rixham
Edited by Barry Butler, Liz Merry and Diana Young
I
I
t’s cheaper to save energy than to make energy. If you want to offset $100
a month in utility bills, the right place to start is not with a solar array on
the roof, but with insulation under it.
First, Look at Your Heating and Cooling Bills
Whether you battle high heating or cooling expenses, a quality roof and
windows, good insulation and proper sealings are important in maintaning
a controlled climate. Most homeowners can save 20 to 25 percent by caulking air leaks around windows, doors, foundations and soffits. Check the
attic insulation, too. It’s cheap to add an extra layer of batting or blown-in
cellulose. It’s more expensive to swap out old single-pane or metal-frame
windows for more efficient modern insulated triple-pane wood- or vinylframe windows. The cheapest fix of all is to renew weather-stripping around
all doors and window sashes, and put insulating covers on pet doors.
Spending $2,000 on insulating upgrades may cut heating costs by 50
percent and pay for itself in about three years. The U.S. Department of
Energy (DOE) website (energysavers.gov) includes interactive worksheets
to help you figure out how much more insulation you may need (depending on your climate), how much it may cost and, depending on what you’re
paying for heat energy today, how long the payback period may be.
Heating and cooling systems can usually be improved. Be sure to
change the furnace air filter quarterly. Get ductwork cleaned and air leaks
sealed, and make sure that ducts are insulated at least to local codes. Your
ductwork should be set up to heat (or cool) recirculated air from inside the
house, but the furnace should draw combustion air from outside — you
don’t want to burn fuel using air you’ve already paid to heat.
If you heat with oil or electricity, consider installing a modern highefficiency gas furnace or ground-source heat pump. A $6,000 investment in
insulating and HVAC improvements might pay for itself in five or six years.
Not sure where to start? The most direct way to find cost-effective fixes,
especially in an older house, is with a professional energy audit. Check
with your utility company to see if they offer free or reduced-cost audits.
Standard price for this service is $200 to $400. It may include a blower-door
test to locate air leaks.
Look Into Energy-Efficient Appliances
The typical refrigerator built in 1980 costs about $154 in electricity to run
for a year, at today’s average rate of 11 cents per kilowatt-hour. A modern
high-efficiency refrigerator runs for about $55 a year. The average homeowner would save $99 a year — enough to pay for the refrigerator in a few
years. A new water-heating system may be cheaper still.
Read the full article at solartoday.org/solar-basics.
6
A SES NATIONAL S O L A R TO U R nationalsolartour.org
n most parts of North America, the best bang for your solar energy buck is
with domestic solar water heating (DSWH). It’s a no-brainer in the desert
Southwest and in semitropical Florida and Hawaii.
A complete DSWH system can be installed for $4,000 to $7,000, depending on its size, complexity and the climate. These systems are now eligible
for the 30 percent federal tax credit. At today’s energy prices, over the life of
the system, the cost to operate is about 20 percent lower than a conventional gas water heater and 40 percent lower than an electric one. As gas
and electricity prices rise, DSWH will look like a better and better deal. The
benefits are much greater since solar energy avoids 2,400 pounds of CO2
per year and provides a secure domestic source of hot water.
Solar water-heating systems come in two flavors: passive and active. In
warm climates, a simple passive system can provide plenty of hot water.
Passive Solar Water-Heating Systems
Passive systems are installed in areas where freeze protection is not
an issue. The most common types are integral collector storage (ICS) and
thermosiphon systems.
In an ICS (or breadbox) system, cold city water flows into a rooftop collector. The collector holds 30 to 50 gallons of water in a serpentine pipe with
a heat-capturing coating. Hot water from the collector flows directly to a
conventional water heater; in effect the sun does most of the work usually
performed by the water heater’s burner. As hot water is withdrawn from the
water heater, cold water is drawn into the collector, driven by pressure in
the city water pipes.
A thermosiphon takes advantage of the fact that water rises as it’s
heated. Solar-heated water in a flat-plate collector rises through tubes and
flows into the top of an insulated storage tank. Colder water at the bottom
of this tank is drawn into the lower entry of the solar collector. Water thus
flows in a continuous loop, continually reheating during daylight hours.
When a hot water tap is opened in the house, hot water flows from the top
of the storage tank, and is replaced with cold city water flowing into the
bottom of the storage tank.
Although the system is simple, thermosiphons put an 800-lb storage
tank high on the roof, which should be reinforced to support it. Other solar
water-heating systems put the storage tank at ground level or in the basement, where it’s not a structural challenge.
Active Solar Water-Heating Systems
Active systems use an electric pump to circulate water through the
collector. In warm climates, a direct (or open-loop) system is practical: City
water goes into an insulated storage tank. A pump draws water out of the
storage tank to pass through the solar collector and go back into the tank.
Read the full article at solartoday.org/solar-basics.
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
ILLUSTRATIONS BY KURT STRUVE
Solar Electric System Basics
Wind System Basics
Edited by Joseph McCabe, P.E.
By Mick Sagrillo
A
I
basic home photovoltaic (PV) system consists of weather-protected
panels, also called modules, fastened side-by-side on a racking system
to form an array. The PV modules produce direct current (DC), which flows
to an inverter. The inverter changes DC voltage to alternating current (AC)
for the household electric circuit.
Excess power from the inverter may flow out of the house through the
utility company’s electric meter, into the city-wide grid. The utility will credit
the outflowing electricity against electricity purchased from the grid at
night. This process is called net-metering.
In an off-grid system, common in remote locations, DC power flows from
the modules through a charge controller (also called a regulator), an electronic device that produces a smooth flow of current at the desired voltage.
From the charge controller, the power can go to a set of storage batteries
and then on to the inverter, as needed.
Most home systems today use crystalline silicon PV modules because
they produce the most power in the limited space available on a house roof
(cheaper thin-film modules are common in large industrial arrays).
Crystalline PV cells use silicon, a little bit of boron and phosphorus along
with anti-reflection materials and a screen printing of electrically conductive
grid lines on the top and a coating of aluminum on the bottom to collect the
electrons.
Thin-film modules are made from very thin layers deposited on an electrical conducting surface. These materials may originate as silane gas for
amorphous silicon, cadmium and tellurium for CdTe, or copper, indium, gallium and selenium for CIGS. The deposition techniques may include sputtering, co-evaporation in a vacuum, electro-deposition, sintering or other
techniques. Many variations of thin-film materials are being investigated for
low-cost manufacturing and higher solar-to-electrical efficiencies.
Installation Location
Location is critical to PV performance. The array should face the sun.
This usually means due south, though if you have a heavy air-conditioning
load in the late afternoon you may want to point the array southwest. The
array should not be shaded during any part of its productive day. The array
should be tilted upward at the correct angle to optimize seasonal exposure
— typically at the angle of your latitude so it gets sunlight at a right angle
at the spring and fall equinoxes. Some arrays can be made adjustable for
varying the angle at different seasons.
Microinverters
Many new grid-tied systems feature microinverters, typically attached to
the rack underneath the PV modules. These systems harness power at the
module level, rather than the system level.
Read the full article at solartoday.org/solar-basics.
Copyright © 2015 by the American Solar Energy Society. All rights reserved.
t seems that everyone is interested in wind turbines, an intriguing
technology that converts the kinetic energy in the moving wind to useful
electricity. Let’s look at the steps required to see if a small wind system
(defined as up to 100 kilowatts in nameplate capacity) is in your future.
Step 1: Examine why you want a wind system. Energy independence?
Lock in future energy costs? Return on investment? Do your part to mitigate
global climate change? Support the renewables industry? Power an electric
vehicle? Set an example for your family and community? Put your money
where your values are?
These are valid reasons for installing a wind turbine. Your goals will affect
the system you choose, the amount of money you are willing to spend, and
the time you are willing to commit to being your own utility.
Step 2: Quantify the amount of electricity you use now. Most people put
up only one wind turbine and they usually want it to generate the amount
of electricity they consume over the course of a year. Cost-effectiveness
changes with increasing size — the bigger the turbine, the more you spend
on the installation, but the cheaper the cost of electricity will be over the
life of the system. Matching the size of the system to your annual load maximizes the value of your investment if you can’t sell the excess.
Step 3: Reevaluate how you use electricity and why. It’s always cheaper
to save energy than it is to generate it, so streamline your consumption.
The most cost-effective way is to alter your electricity-use habits — turn off
lights in unoccupied rooms, mind the thermostat, put “vampire” electronics on a switchable power strip. But habits are hard to change. Investing in
high-efficiency appliances makes excellent sense. The rule of thumb is that
every $1 spent on efficiency saves $3 in wind system costs.
Step 4: Determine how much fuel (wind) you have at your site. The best
way is to hire a small-wind site assessor to evaluate your site and wind
resource. This service may be available for a fee from a local wind installer,
but be sure to shop around. You want an assessment of your wind resource,
not a sales pitch for a particular turbine or manufacturer. Consider this akin
to hiring a building inspector to evaluate a house you are interested in buying. The inspector’s job is to evaluate the condition of the house and report
back to you so you can make an informed decision as to whether or not the
house is a wise investment. During this process, the inspector represents
your interests only, as should a wind site assessor, and present you with
unbiased information to evaluate.
Read the full article at solartoday.org/solar-basics.
Find more solar basics, on topics including ground
source heating and cooling, passive solar building and working with a solar contractor, at solartoday.org/solar-basics.
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