The Power of Solar Energy
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The Power of Solar Energy
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 2
INTRODUCTION:
The power of solar energy is fascinating. How can something transform sunlight
into electricity? The purpose of this informational bulletin is not to answer that
question. Rather, this bulletin is intended to address many of the questions members of the
Cooperative have about solar energy.
As you can see from each region of the map, the distance, angle, and duration of the sunlight all
affect solar energy production. Given the sunlight available in the areas served by the
Cooperative, one could reasonably expect 4.5 to 5.0 hours (see below) of solar production.
Obviously, the duration of the sunlight during most days is much longer. This map translates
available sunlight to a continuous duration of energy production at a solar panel’s full capacity.
A number of hours (including mornings, evenings, and cloudy periods) will have less than
ideal solar production capabilities. Only a few hours will approach maximum production
capacity. Averaged out, solar energy (rated at maximum capacity) is available in the
Cooperative’s service area about 4.5 to 5.0 hours during an average 24-hour day.
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 3
BACKGROUND:
At the outset, it is important to recognize some of the common advantages and
disadvantages associated with solar energy. The Cooperative recognizes not all
members agree on the balance of advantages and disadvantages of solar power. Some are
opposed to any generation source that produces carbon emissions. Some are opposed to any
form of tax subsidies. This bulletin cannot resolve, nor is it intended to inflame positions held
by individual members. The information provided is intended to simply present facts.
Advantage Disadvantage
Solar energy consumes more land
footprint per kilowatt of power
Solar energy does not produce any generation.
Environmental
pollutants or other emissions.
Some panels have questionable
manufacturing processes.
Solar energy indicates a high degree of If NOT properly interconnected, solar
Safety
safety when properly connected. energy can be lethal.
Does not produce energy at night.
Reduced output during cloudy periods,
Reliability
Functional with sunlight. mornings, and evenings.
(See previous page)
Overall production diminishes as solar
panels age.
Like all generators, solar panels and
their power inverters can fail.
Solar panels are not prone to
mechanical maintenance and wear For optimum performance some
Durability
associated with conventional turbine maintenance is required.
power generation.
Panels are not immune from physical
damage.
Sunlight is free. Solar bears no fuel cost
to generate each kWh.
Lifetime costs per kWh produced are still
Affordability Federal tax credits can mitigate some of higher than most traditional sources of
the upfront (fixed) costs. energy.
Fixed costs per kWh are on the decline.
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 4
PRODUCTION MODELS:
Electric energy (no matter the means of production) can, to a limited extent, be
stored in batteries. However, energy is lost during the storage and subsequent
release of energy into and out of a battery. While it is practical to store energy in a battery that
might power something like a calculator, it quickly becomes impractical to have sufficient
battery storage to power electrical needs of a conventional home.
Batteries for Community Solar
and Utility Scale do not exist.
Utility In light of the inherent storage
Scale
Community limitations and the intermittent
Solar
reliability (see page 2) of solar
Home or
Rooftop
energy, conventional sources of
(Net Utility Scale power generation
Battery Metering) must continue to exist in order
Charging to meet electrical demands at
all hours of the day.
However, that is not to say solar energy does not have an important role in energy production:
• Battery Charging: Solar panels are successful at charging batteries. This can be a valuable
method for low energy appliances or providing power to things like electric fences that are
not in close proximity to conventional power sources.
• Home or Rooftop (Net Metering): At the time this bulletin was issued, 68 of the
Cooperative’s 92,100 member-accounts utilize on-site solar panels through the
Cooperative’s Net Metering agreement. (This bulletin will go into greater detail about the
opportunity for members to participate in Net Metering.)
• Community Solar: A number of for-profit and not-for-profit enterprises (some who are
utilities and some who are not) are embarking upon projects that divide a cluster of panels
among interested individuals. There is a wide variety of economic structures to fund the
panels’ up-front costs and/or generate profits. Often, subscriptions to a pro-rata share of
the panels are sold to individuals.
Without regard to any profit motive, the success in generating individual subscriptions is
fundamentally connected to a utility’s electric rates. Carroll Electric’s rates are among the
lowest in the nation. While low rates are good for the Cooperative’s members, they are a
disadvantage in generating individual subscriptions in a Community Solar project.
The Cooperative will be monitoring closely the developments in Community Solar.
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 5
• Utility Scale: Conventional power plants in Arkansas typically range from 500 to 1,800
megawatts.
A 12-megawatt solar array is planned for construction in Arkansas in 2015. This will by far,
be the largest installation in the mid-south region of the United States. This installation will
utilize 100 acres of land near Camden, Ark., and will primarily serve one industrial
consumer. However, Arkansas Electric Cooperative Corp. (Carroll Electric’s wholesale
power supplier) has agreed to purchase any excess generation not needed by the industrial
consumer.
Based on this project, it is important to note more than 4,100 acres of land would be
required for a solar installation that could match (only during certain hours of the
day/year) the capacity of a conventional 500 megawatt power plant.
For illustration purposes, consider the actual “time of use” curves for the Cooperative:
Even though maximum
solar production occurs Winter Summer
during the middle of the 600mW
day, it remains a 8:00 AM
488mW
common misconception
500mW 5:00 PM
that solar energy 408mW
substantially reduces
the need for 400mW
conventional power
plants. While solar 300mW
energy is chipping away
at the run time of 200mW
conventional plants,
these plants, as 100mW
illustrated to the right,
must remain in service 0mW
to meet demands 24
12:00 PM
1:00 PM
2:00 PM
3:00 PM
4:00 PM
5:00 PM
6:00 PM
7:00 PM
8:00 PM
9:00 PM
10:00 PM
11:00 PM
1:00 AM
2:00 AM
3:00 AM
4:00 AM
5:00 AM
6:00 AM
7:00 AM
8:00 AM
9:00 AM
10:00 AM
11:00 AM
12:00 AM
hours a day.
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 6
Thanks to https://enlighten.enphaseenergy.com/pv/public_systems/ it is easy to see how
much solar power is available when it is needed most.
As you can see from the illustration above, the intensity of the sun is greatest during the
middle of the day as indicated by the light blue areas. The dark areas indicate night, clouds,
or in the case of February 16-19, 2015, snow-covered panels.
It is also important to
As you consider solar benefits, this conversion understand this particular
system has a total of 90
between “watt-hours” to “kilowatt-hours”
panels installed with micro
to help you understand how inverters (see appendix A).
much energy you can save.
It is further important to
understand, the 4 “watt-
hours” illustrated above are equal to four one-thousandths (4/1,000) or a total of 0.004
“kilowatt-hours.”
You are billed by the Cooperative in “kilowatt-hours.”
Consistent with the general indications of manufacturer’s warranties (Appendix A), these
panels have produced a declining amount of energy over the past three years. For 2014,
the panels produced 9% less than they did during 2012 (the first full year of operation).
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 7
Based on the conditions from the previous page, the harsh reality of solar energy production
would require about 2,600 square miles of solar panels to match the Cooperative’s
expected peak demand for power.
This would take a land mass that
would cover four times all of the land
and water in Carroll County…and this
would still not produce energy at
night.
Land: 630 sq. miles
Water: 8.7 sq. miles The big picture point is, solar energy
is not a dependable or desirable
resource to deal with the peak
demand for electricity.
Obviously, this scale of facilities
would produce too much energy
during other hours of the year. It
would waste the power of solar
energy to build more capacity than is
needed.
Again, until energy can be stored efficiently, conventional plants must remain. A balanced
strategy is required.
However, those who believe the utility industry, or even the Cooperative is against solar
power, are mistaken. If the current price trends and tax credits continue into the future,
the Cooperative expects that Utility Scale solar generation could become a solid business
decision.
Even if trends do not continue, it is a predictable possibility Utility Scale solar generation will
be required to meet increasingly stringent government regulations.
As these trends progress, an important part of the public policy debate likely will shift to the
acquisition and siting of thousands of acres of land for solar generation projects.
THE COOPERATIVE’S STRATEGY:
The Cooperative is very sensitive to Utility Scale land use requirements and
realizes the more land required for a solar project, the more valuable land resources will
become. In contrast, solar energy will become less valuable as it is deployed and as it
consumes more land resources.
The Power of Solar Energy
Carroll Electric Cooperative Corp. Page 8
For now, the Cooperative is embarking upon a solar demonstration project. This demonstration
will harvest real life, side-by-side production data about various solar energy technologies. The
project is expected to be up and running in 2015.
This information will be shared with members of the Cooperative to use for considering Net
Metering and for future planning of Community Solar/Utility Scale projects by the Cooperative.
When a Community or Utility Scale deployment of solar energy is in the best interest of the
Cooperative’s members, Carroll Electric will attempt to maximize its efficiency…in production,
cost, and land use.
NET METERING:
If you are interested in Net Metering, the Cooperative
CECC Solar Net Metering
invites you to join approximately 70 other Carroll Electric members. Accounts by County
While some would argue this doesn’t sound like very many, Barry, MO 3
northwest Arkansas has the highest concentration of Net Metered Benton, AR 23
accounts in the state. Boone, AR 1
Carroll, AR 22
Madison, AR 6
Carroll Electric is happy to visit with you about any facet of Net Newton, AR 12
Metering. If we don’t have the answer, we will do our best to get it Stone, MO 1
for you. Feel free to make inquiries at 1-800-432-9720. Total 68
Arkansas Law (Code § 23-18-601) enables you to participate in Net Metering within certain
requirements prescribed by the Arkansas Public Service Commission (APSC). As presently
implemented, you can receive a full retail kWh credit for each kWh generated on a monthly net
basis, even if at the time that kWh is generated it flows back onto the Cooperative’s system.
In essence, the other members of the Cooperative are purchasing these kWh at retail prices
instead of wholesale. This subsidy to incentivize Net Metering is insignificant today. However,
if distributed generation gains market share, those who cannot afford the up-front costs
associated with Net Metering will bear an increasing share of the costs for those who can make
these investments. Regardless of how you feel about this, the bottom line is to understand
there is no assurance this level of incentive will continue into the future.
To assist members in navigating the process of Net Metering, the Cooperative has developed a
checklist for members to use:
Net Metering Checklist:
1-800-432-9720 | www.carrollecc.com Ask for one of our
Contact the
Cooperative P.O. Box 4000 Member Services
Berryville, AR 72616 Representatives
Certain safety requirements are your legal responsibility.
Review The Cooperative is also required to ensure the connection to your Net
Information Metering facility meets certain code requirements.
Packet The goal is to ensure you, the public, and our employees operate in a
safe environment.
Solar panels come in a wide range of selections.
This is a good area for you to do your homework
Consider prior to signing any contracts.
Product Often overlooked, is the type of power inverter Appendix A
Options needed to make your system function its best.
Understand what the product warranty covers.
Consider
How a panel is installed dramatically affects its
Installation performance.
Appendix B
Methods
The economics can vary greatly based on your
Do the Math decisions above.
Appendix C
The Cooperative cannot install the system for
you. Even though Carroll Electric will inspect the
Select a system to ensure it meets safety specifications,
Qualified your electrical components must be installed by Appendix D
Installer a licensed electrician. All hardware and
components must be UL listed. It is up to you to
select someone you trust.
Complete all requested information, including a Within 30 days, one of the
Return Cooperative’s technicians
diagram of the system.
Required will schedule a safety
inspection of your
Documents A completed Net Metering Agreement must be facilities. Pending
approval, a unique meter
to the signed by the member holding service at this required to properly bill
Cooperative location. your account will be
installed.
After the field visit has been satisfactorily
completed, the Cooperative will execute the
Keep your agreement and return a signed copy to you.
Agreement The billing for your account will continue based on rates, terms,
on Hand and and tariffs approved by the APSC and the calculations of the meter. Appendix E
your System You must notify the Cooperative of any modifications to your Net
Metering installation 30 days in advance of making any changes.
Functioning Net Metering installations require annual inspections at the rates
and tariffs approved by the APSC.
The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.1
Product Options: PANELS
Power Typical
High Space Low Upfront High Cost
Technology Output Residential
Efficiency Cost Efficiency
Efficiency Installation
Amorphous Not practical for residential applications.
Thin Film
Cadmium Telluride **
Panels Copper Indium
Gallium Selenide
* *
Organic Photovoltaic
Crystalline Monocrystalline
Silicon
Panels Polycrystalline
* High power output and space efficiency have only been achieved in laboratories.
** If space efficiency is not an issue, this type should be given consideration in residential applications.
Thin Film Solar Panels
There are four common thin film solar panels:
• Amorphous Silicon (a-Si) Panels: Because the output of electrical power is so low, a-Si
solar cells have traditionally only been used in small scale applications such as in pocket
calculators. However, recent innovations have made them more attractive for large
scale installations. A manufacturing technique called “stacking” is being utilized bringing
their efficiency up to 6-8%. The stacking process involves stacking several layers of a-Si
solar cells on top of one another. Stacking is expensive. Therefore, the Cooperative
does not recommend a-Si panels for residential installations.
• Cadmium Telluride (CdTe) Panels: CdTe panels have surpassed the cost-efficiency of
crystalline silicon panels in large scale applications. The efficiency of CdTe panels varies
from 9-11%. In residential applications, space efficiency is often an issue and other
types of panels are available that have higher space efficiency values. Therefore, CdTe
panels are not typically a homeowner’s best choice. However, if space efficiency is not
an issue, CdTe panels should be given consideration.The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.2
Copper Indium Gallium Selenide (CIGS) Panels: Compared to other thin film panels,
CIGS panels currently have the most potential. In laboratories, an efficiency rating of
18.7% has been achieved, but it has yet to be proven if CIGS panels can be mass
produced at that efficiency. For now, CIGS panels do not appear to be ideal for a
homeowner.
• Organic Photovoltaic (OPV) Panels: OPV panels consist of at least one layer of organic
electronic material sandwiched between two metallic layers. One of the metallic layers
is typically made of indium tin oxide while the other is made of aluminum, magnesium,
or calcium. The electronic material is typically a small molecular polymer such as plastic.
OPV panels are relatively inexpensive to manufacture, but their efficiency ratings are
typically less than 1%. OPV panels are not recommended for residential applications.
Depending on the technology, thin film prototype panels have reached efficiencies between
7-13% and production panels operate at about 9%. In the future, thin film panels are
expected to reach efficiencies of 10-16%. About 5% of panels installed in the United States
residential sector are thin film panels.
Crystalline Silicon Panels
While thin film panels will produce electricity, the Cooperative typically recommends using one
of the following types of crystalline panels:
• Monocrystalline Panels: These are typically the most efficient panels
manufactured. Their coloring is uniform which is indicative of high purity silicon.
Advantages
Best efficiency rating (15% - 20%)
Higher efficiency ratings = higher space efficiency (do
more with less)
Highest life expectancy - many companies offer a 25
year warranty (see below).
Tend to perform better than similarly-rated
polycrystalline panels in low-light conditions.
Disadvantages
Least affordable upfront cost.
During the manufacturing process large amounts of silicon are wasted.
(http://news.yahoo.com/solar-industry-grapples-hazardous-wastes-184714679.html)The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.3
• Polycrystalline Panels: These have lower efficiency ratings than monocrystalline
panels. Their coloring is sometimes described as “sparkling blue” which indicates
lower purity silicon was used to manufacture them.
Advantages
The manufacturing process is less expensive than that
of monocrystalline panels making polycrystalline
panels more affordable.
The manufacturing process yields less wasted silicon.
(http://news.yahoo.com/solar-industry-grapples-hazardous-
wastes-184714679.html)
Disadvantages
Lower efficiency rating (13% - 16%) than monocrystalline panels.
While polycrystalline panels typically have the same warranty as
monocrystalline panels, research indicates a shorter life expectancy.
Some believe the “sparkling blue” coloring to be less aesthetically pleasing
than the uniform coloring of monocrystalline panels.
Most (95%) residential panels installed in the United States are made from crystalline silicon.
The purity level of the silicon holds a direct relationship with the efficiency of the panel.
Product Options: POWER INVERTERS
There are three main types of solar power inverters: stand alone, grid tie, and dual inverters.
The following explanations will help one decide which inverter is best for his/her situation.
Also, micro inverters are relatively new technology to the solar industry. The advantage of
using micro inverters will also be discussed.
1. Stand Alone Inverters are used for off-grid solar arrays. With off-grid arrays, the
solar panels generate direct current (DC) electricity. The electricity is stored in
rechargeable batteries. When energy is required, direct
current is sent from the battery to the stand alone inverter
where it is converted to alternating current (AC). AC power
is the type of power Carroll Electric provides to its
members’ homes and businesses. Employing the use of DC
appliances would eliminate the need of an inverter in off-
grid systems.The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.4
If any large appliances or equipment are to be powered using a stand-alone solar
system, it is necessary that a surge-compliant inverter be installed. These inverters are
also necessary for most residential and commercial grid tie solar applications. Large
appliances require a surge of energy when first being powered up, therefore it is
necessary the inverter is able to supply this surge of electricity when required. Most
larger off-grid inverters have this capability. However, it should be verified this feature
is available before making a purchase.
2. Grid Tie Inverters are for use in any situation that a solar array is connected directly
to the local power grid. By law, a Net Metering Agreement must be signed and all
required safety measures must be achieved before tying to the
grid. Please note when connecting to Carroll Electric’s grid, all
equipment must be UL listed.
With grid tie solar systems, direct current is generated by the
solar panels. The DC power is sent to the grid tie inverter where
it is converted to AC power. From the inverter, the AC power is
sent to Carroll Electric’s meter. The meter constantly monitors
the amount of electricity being used by your home or business
and the amount of electricity you are producing. At the end of
each billing cycle, the meter is read. If more electricity is used
than the panels produced, Carroll Electric bills the member for the net amount. If the
panels produce more electricity than the equipment being powered has consumed, the
net difference is rolled over to the next billing cycle.
All grid tie systems are required to have a solar energy inverter with anti-islanding
protection which forces the solar array to shut down in case of power outages. Without
anti-islanding protection, your solar array would continue to generate electricity and
energize the electric grid during power outages. This energy would stay in the local
power grid and is referred to as an island. These islands are extremely dangerous for
utility workers who are repairing the grid during a power outage or anyone who might
come near a downed power line.
3. Dual Inverters are also known as backup battery inverters and are used in a multi-
function solar facility. In this system, the direct current generated by the solar panels is
first sent directly to a battery array. The energy from the batteries is then sent to theThe Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.5
inverter and converted to alternating current whenever electricity is required.
However, when the batteries are fully charged, any excess
direct current electricity generated is sent directly to the
inverter and is then sent into the local power grid. This
system combines the other two systems into one. A dual
inverter allows one to produce, store, and consume any
electricity a solar facility produces. A Net Metering
Agreement and satisfaction of all safety protocols are
required when installing this type of system or any other
system that is tied to the grid.
4. Micro Inverters, as previously mentioned, are relatively new technology in the solar
power industry. If micro inverters are not used
when panels in a solar array are wired
together, the panels must be wired in series. A
series circuit relies on all components to
function properly or the entire system will not
work. An example is a string of Christmas lights
not working because of one bad bulb.
Micro inverters allow solar panels to be wired in parallel. A parallel circuit allows
electricity to continue to flow even if one or more components of the circuit fail. This
innovation makes solar arrays more reliable than they were in the past. A central
inverter is not needed if micro inverters are used. Micro inverters are highly
recommended. Virtually all new residential installations utilize micro inverters.The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.6
Product Options: WARRANTIES
When considering which vendor to select, you should carefully read
the warranty in effect at the time. Like all products, solar panels are
subject to failure. Most solar panel manufacturers offer a 20-25 year
warranty for the panels they manufacture. It is important to
understand the 20-25 year warranty is generally only for power output. Shorter warranties
generally apply to batteries (if installed), inverters, tracking motors (if installed), and parts and
labor. With any warranty, there are always exceptions. One of the most common warranty
stipulations is proper equipment installation. With this in mind, be sure to hire a qualified and
trustworthy contractor.
Power Output
Chart 1: Solar Panel Warranty Comparison
Most solar panel production (As a Percenage of Rated Output)
warranties are for less than the
rated output and drop over time. 100%
Defective Panels
Solar panels are typically 95%
warranted for defective material or
workmanship (factory defects). tenKsolar
90%
This portion of the warranty is Trina Solar
typically around 10 years in length Sunpower
from the date of installation. A 85%
Standard
proper warranty should cover Suntech
items such as delamination or early Yingli Solar
failure. (See below.) 80%
Batteries
Battery warranties range widely 75%
1 3 5 7 9 11 13 15 17 19 21 23 25
from 1 - 10 years, but it is said that
Year CECC Feb. 2015
many batteries have a life
expectancy of up to 20 years. Batteries tend to be one of the least troublesome components of
a solar system. If one malfunctions, it is most likely due to a factory defect and the failure
typically occurs before the warranty has expired.
Inverters
Inverters typically carry 5 - 10 year warranties. Top manufacturers claim life expectancies of 20The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.7
years. An inverter is usually the most expensive single piece of equipment in a solar facility.
Inverters are also the most common component to fail. It is highly recommended to install a
quality inverter. With most inverters, there is a direct correlation between quality and length
of warranty. Higher quality inverters typically have warranties of approximately 10 years.
Tracking Systems
A variety of systems are available to track the sunlight (see Appendix B). Some are motorized
and some utilize other technologies to initiate movement of the panels. Some warranties
require routine maintenance such as greasing the moving parts and can vary as much as 2 to 10
years in length. The Cooperative recommends you carefully evaluate the warranty elements of
the tracking system being considered.
Parts and Labor
Parts and labor warranties are sometimes offered by installers in addition to the factory
warranties of the system components. It is recommended that a dealer who offers a parts and
labor warranty be hired.
Additional Considerations
• Solar panels do not operate well in high heat locations. Always allow good airflow
around panels. For example, never mount
solar panels directly to a roof. A raised
mounting bracket is highly recommended
for roof installations. This allows for airflow
across the back of the panel. Lack of airflow
around a panel can be extremely harmful to
the panel. In fact, it is rarely recommended
to install panels on a roof. However,
sometimes it is the best option. It is a good
idea to consult with your installer to ensure your installation method does not invalidate
your product warranty.
• One of the common sources of panel failure is delamination
(http://breakingenergy.com/2011/10/07/solar-panels-dont-
Delamination due to humidity.
work-and-no-one-knows/), which can result from loss of
adhesion between encapsulants. Encapsulants are
the outer layers of the panel that encompass the
other layers of the panel. Within the encapsulants
are more layers that gather the sun’s energy.The Power of Solar Energy Appendix A: Product Options
Carroll Electric Cooperative Corp. Page A.8
According to researchers, higher than acceptable sodium phosphorous content in the
outer glass layer of a panel can cause delamination, especially in damp/hot areas. This
can only be avoided during the manufacturing process. The best way to address this
issue is to ensure the panels are purchased from a reputable manufacturer who will
honor the warranty of the panels.
• Production warranties generally do not cover
accumulations of dust, leaves, snow, and ice or panel
installations that receive any shade from sunlight.
Generally, if any portion of a single panel is covered by
shade or anything else, at minimum, that panel will
stop producing power. Without a micro inverter, the
entire array will stop producing power.
Do your homework to understand if your panels are insured for
damage by your property owner’s insurance policy. For rooftop
installations, it is a good idea to ensure roof damage and/or leaks
remain adequately covered.
• Physical damage to a solar panel due to hail, tree limbs, fire, or other hazards is typically
not covered by the warranty.The Power of Solar Energy Appendix B: Installation
Carroll Electric Cooperative Corp. Page B.1
Installation: The output of your system depends heavily
upon the installation method. Here are four common methods:
1. Fixed Tilt
The panels should face south and be tilted at latitude. An
average latitude value for northwest Arkansas and southwest
Missouri is 36.5°. A GPS unit can be used to find the exact
latitude of an installation site. Facing the panels south and
pitching them at latitude allows for optimal power generation
from a fixed tilt installation.
2. One-Axis Tracking
One-axis solar trackers rotate on one axis moving back and
forth in a single direction. Different types of one-axis trackers
include horizontal, vertical, tilted, and polar aligned which
rotate as the names imply. Because this installation has the
potential to absorb more sunlight, it is better than a fixed tilt
installation. There are automated and manual versions of one
and two-axis tracking systems.
3. Two-Axis Tracking
Two-axis trackers continually face the sun because they can
move in two different directions. Types include tip-tilt and
azimuth-altitude. Two-axis tracking is typically used to orient a
mirror and redirect sunlight along a fixed axis toward a
stationary receiver. Because these trackers follow the sun
vertically and horizontally they help obtain maximum solar
energy generation.
4. Roof Mount
The chart below gives tilt angles for various roof pitches. If possible, it is best to mount
panels on a freestanding structure instead of a roof. Roof mounted panels make it more
difficult to maintain the panels and roof.
Roof Pitch 4/12 5/12 6/12 7/12 8/12 9/12 10/12 11/12 12/12
Degrees of
18.4° 22.6° 26.6° 30.3° 33.7° 36.9° 39.8° 42.5° 45°
Tilt AngleThe Power of Solar Energy Appendix B: Installation
Carroll Electric Cooperative Corp. Page B.2
Before you install on a rooftop, you should consider the age, condition, and structural
strength of the existing roof. It may pay dividends in the long term to install new
shingles and/or roof decking prior to installing solar panels.
Consider Shading
The condition and cleanliness of a solar
system can be excellent, but if any
portion of the array is covered by
shade, the entire system could be
rendered inoperable. Consider growth
patterns of trees and other vegetation
so no shadows are cast on the array.
Plan ahead, to ensure the array is not
shaded by any future structures (storage shed, home addition, additional solar panels,
etc.) If periodic shading is unavoidable, the use of micro inverters (Appendix A) is
strongly recommended.
Panel Orientation
Careful planning should be done when initially orienting a solar array. If not done
properly, you will not experience the full benefits of solar energy.The Power of Solar Energy Appendix C: Do the Math
Carroll Electric Cooperative Corp. Page C.1
The Math:
For many members,
solar energy is NOT about the
math. A number of members
feel it is the responsible thing
to do and view it as their
contribution to the planet.
The Cost/Benefit Analysis on
the following page will help
you understand your
contribution as well as the
economic benefits it
produces.
The Cooperative
recommends you maximize
the energy efficiency of your
home first. If you want to install solar panels too…Carroll Electric is here to help facilitate that.
Visit www.carrollecc.com for energy efficiency tips or contact one of our representatives for a
free home energy audit. The Cooperative’s commitment to energy efficiency has earned Carroll
Electric recognition as an Energy Star Partner.
In 2013, Carroll Electric was awarded the EPA’s Leadership
in Housing Award recognizing the important contributions
made by the Cooperative toward energy efficiency
initiatives in members’ homes.
Did you know…
Until December 31, 2016, the federal government is offering a 30% tax credit, with no upper
limit, for installation of:
(1) geothermal heat pumps;
(2) solar energy systems; and
(3) residential wind turbines.The Power of Solar Energy Appendix C: Do the Math
Carroll Electric Cooperative Corp. Page C.2
Cost Benefits
Up-front costs: Energy Savings:
1. Solar panels $ A. Watt rating for each panel watts
2. Inverters $ B. Number of panels panels
3. Batteries $ C. Total watts (line A x line B) watts
4. Installation $ D. Conversion factor (1,000 watts = 1 kilowatt) 1,000
5. Total (lines 1-4) $ E. System rating (line A divided by line B) kW
F. Expected efficiency (Appendix A: Chart 1).
6. Interest or financing charge This percentage should reflect the drop in
$ % percent
warrantied output and could reasonably
7. Federal Tax Credit (if applicable) $ be between 80%-97% over the life of
system.
Estimated maintenance/replacements over useful life: G. Expected output (line C x line D) kW
8. Solar panels $
9. Inverters $ H. Average generation time in hours. hours
10. Batteries $
11. Labor $ I. Expected kWh per day (line E x line F) kWh/day
12. General maintenance $ J. Expected kWh per year (line G x 365) kWh/year
13. Property insurance $
14. Total (lines 8-13) $ K. Avoided cost of power (per kWh) $ 0._______
15. Projected Lifetime COST L. Estimated Annual BENEFIT
$ $
(line 5 + line 6 - line 7 + line 14) (line J x line K)
Payback period in years
(line 15 divided by line L)
years
See Table 1 and Table 2 on next page.
According to research by https://notalotofpeopleknowthat.wordpress.com/2014/04/20/solar-panel-degradation/ failure rates of some panels range
from 5.5% to 22%. See Appendix A for the types of warranty information you should understand about your specific product installation. It is
impossible to accurately predict costs not covered by product/vendor warranties over the life of your system.
See Appendix E to get an idea of what is necessary to keep your system operating at its best. Some community solar projects are projecting 2.5%
of investment as a reasonable estimate.
The National Renewable Energy Laboratory estimates 4.5 to 5.0 hrs. per day. It is important you consider if your system's installation method (See
Appendix B) will maximize energy output before utilizing NREL's estimates. Data indicates some systems only capture approximately 3.0 hrs. per
day. The tilt and direction of your panels matter.
For the 25 years between 1989 and 2014, Carroll Electric's average residential rate per kWh rose from $0.0754 to $0.0970. This is an annual increase
of 1%. However, these amounts include fixed charges which are unavoidable by Net Metering accounts. These figures also include the incentives to
promote Net Metering that are embedded into existing law and regulations. It is impossible to predict future fixed charges or what the law and
regulations may hold for Net Metering. Using the variable portion of 2014 residential rates and applying the 25-year historical trend to that portion,
one could expect the variable component of rates to average approximately $0.0987 over the next 25 years.The Power of Solar Energy Appendix C: Do the Math
Carroll Electric Cooperative Corp. Page C.3
Table 1. Time Value of Money Total Interest Expense Per $1,000
Interest Rate: 5% 6% 7% 8% 9% 10%
5 years $ 132 $ 160 $ 188 $ 217 $ 246 $ 275
10 years $ 273 $ 332 $ 393 $ 456 $ 520 $ 586
15 years $ 423 $ 519 $ 618 $ 720 $ 826 $ 934
Viewed as a
20 years $ 584 $ 719 $ 861 $ 1,007 $ 1,159 $ 1,316
Loan 25 years $ 754 $ 933 $ 1,120 $ 1,315 $ 1,518 $ 1,726
30 years $ 933 $ 1,158 $ 1,395 $ 1,642 $ 1,897 $ 2,159
Example : A ten year loan at 6% for a $20,000 system would create $6,640 ($332 x $20k) in interest expense.
If paid from personal savings, what "Return on Investment (ROI)" is expected?
(ROI based on $1,000 investment)
Interest Rate: 1% 3% 5% 6% 8% 10%
20 years $ 220 $ 806 $ 1,653 $ 2,207 $ 3,661 $ 5,727
25 years $ 282 $ 1,094 $ 2,386 $ 3,292 $ 5,848 $ 9,835
Viewed as an
30 years $ 348 $ 1,427 $ 3,322 $ 4,743 $ 9,063 $ 16,449
Investment
Example : A 1% investment return on a $20,000 system expected to last 30 years, would require cost
recovery of $6,960 ($348 x $20k) to match the earnings potential of simple compound interest.
Enter appropriate value from either table above: $
Total Investment (line 5 from previous page) IN THOUSANDS x
Multiply the previous two lines to get…line 6. Interest or financing charge $
Table 2. Property Insurance FREE STANDING ROOF MOUNT
Est. Low Actual Quote Est. High Est. Low Actual Quote Est. High
Current Rates $ 4.99 $ 5.87 $ 6.75 $ 7.03 $ 8.27 $ 9.51
In 5 years* $ 5.78 $ 6.80 $ 7.82 $ 8.15 $ 9.58 $ 11.02
INSURANCE
In 10 years* $ 6.70 $ 7.88 $ 9.07 $ 9.44 $ 11.11 $ 12.78
Rate per
In 15 years* $ 7.77 $ 9.14 $ 10.51 $ 10.95 $ 12.88 $ 14.81
THOUSAND In 20 years* $ 9.01 $ 10.60 $ 12.19 $ 12.69 $ 14.93 $ 17.17
per YEAR In 25 years* $ 10.44 $ 12.28 $ 14.13 $ 14.71 $ 17.31 $ 19.90
In 30 years* $ 12.10 $ 14.24 $ 16.38 $ 17.06 $ 20.07 $ 23.08
* Inflation based on annual increases of 3%.
Enter appropriate value one of the columns above: $
Total Investment (line 5 from previous page) IN THOUSANDS x
Annual Insurance Expense $
System life expectancy (in years) x
Multiply the previous two lines to get…line 13. Property Insurance $The Power of Solar Energy Appendix D: AREA INSTALLERS
Carroll Electric Cooperative Corp. Page D.1
Choosing an Installer: Choosing the right installer can make all the difference in
your satisfaction with your solar system. This bulletin is just a starting point for the
product and vendor options available.
This section is also a good place to define relationships.
The installer has responsibilities to you concerning the installation of your system. That
agreement is strictly between you and the installer.
You and the Cooperative both have responsibilities concerning the Net Metering agreement.
That agreement is strictly between you and the Cooperative. The Cooperative does NOT
recommend you execute a Net Metering agreement provided by an installer. The
Cooperative will provide you the most current version of the Net Metering agreement. The Net
Metering agreement is a total of five pages in the format illustrated below:
The next page contains a list of area installers. The list is not intended to be all-inclusive nor is
it intended as a recommendation by the Cooperative.The Power of Solar Energy Appendix D: AREA INSTALLERS
Carroll Electric Cooperative Corp. Page D.2
Area Installers
Name Address Areas Served Contact Information
Arkansas Wind and 2 Bitworks Way All of Arkansas, Southeast Local: 479-846-9300
Solar Prairie Grove, AR Missouri, and Eastern Toll Free: 888-805-5235
72753 Oklahoma
www.arkansaswindandsolar.com
Eureka Power and 259 CR 301 Northwest Arkansas and 479-244-0377
Light Eureka Springs, AR Southwest Missouri
jl.landrum@gmail.com
72632
Liberty Solar 38 Pintuerero Way Will travel up to three 501-463-2432
Solutions Hot Springs, AR 71909 hours from Hot Springs 501-463-2433
www.libcosolar.com
Pinkley Superior 47 Vaughn St. Northwest Arkansas and 479-253-9544
Electrical and Eureka Springs, AR Southwest Missouri
Communications 72632
Power Source Solar 2201 W. Battlefield Rd. Missouri and parts of (417) 833-4274
Inc. Springfield, MO 65807 Northwest Arkansas
www.solardockpower.com
Preferred Energy 6502 Ming Dr. Missouri and North Office: 417-453-6362
Mountain Grove, MO Arkansas Cell: 417-818-6057
65711
www.preferredenergy.com
Rocky Grove 3299 Madison 3605 Most of Arkansas, 479-665-2457
Sun Company Kingston, AR 72742 Southern Missouri, and
www.rockygrove.com
Eastern Oklahoma
Stellar Sun 126 Bearskin Lake Loop All of Arkansas 501-225-0700
Scott, AR 72142
www.stellarsun.com
Sunrise Solar 1606 CR 329 Northwest Arkansas and 479-244-5139
Eureka Springs, AR Southwest Missouri
eplcarlevans@gmail.com
72632
Stitt Energy Systems 1301 S. 8th St. All of Arkansas and Local: 479-636-8745
Rogers, AR 72756 surrounding states Toll Free: 800-367-7374
www.stittenergy.comThe Power of Solar Energy Appendix E: Keep it Going
Carroll Electric Cooperative Corp. Page E.1
Making the investment is not enough. You
KEEP IT will want to keep your system functioning at
GOING its best. Here are some things to keep in
mind:
General Maintenance
• Depending on where your panels are installed, you
may need to prevent vegetation from
growing in a manner that would shade any
portion of the panel. This includes
overhead vegetation and undergrowth for
free-standing systems.
• The mounting frame on free-standing
panels should be periodically inspected for
structural stability. If the mounting frame shifts, the array may not be at its optimum
orientation.
• Avoid allowing riding mowers, tractors, or other forces (including debris) that could
damage the array or supporting structure near free-standing panels.
• Periodically inspect all system components and ensure they are securely fastened to the
frame. Ensure all electrical components remain unexposed. Over time, electrical
connections can loosen. It is recommended to periodically check all electrical
connections including wiring of panels, inverters, batteries, and any other components
that require wiring. Also, check the integrity of any visible wires.
• Some panels are more susceptible than others to
collecting foreign materials. Layers of dust on a solar
panel will hinder its ability to produce electricity. Dust
may need to be periodically rinsed off the panels using
water. If thick dirt, grime, bird droppings, etc. are
present and cannot be rinsed off the panels, use a Dust covered panels - before
sponge and cold water to remove them. Do not use and after cleaning.
detergents to clean the panels.
• Once the panels are clean, conduct a visual inspection.
Look for cracks, chips, delamination, fogged glazing,
water leaks, and discoloration. If any defects are
found, they should be addressed immediately. Contact
the installer or the manufacturer of the panel. It isThe Power of Solar Energy Appendix E: Keep it Going
Carroll Electric Cooperative Corp. Page E.2
possible the panel is under warranty.
• Snow, ice, leaves, and other types of debris should be removed from panels for
optimum performance. This is especially important if you intend to store or use energy
during the event of a utility outage.
Tracking Systems
• With a manual tracking system, it is recommended to adjust the orientation of the
panels on a weekly basis.
• An automatic tracking system does not have to be adjusted, but it should be periodically
inspected to ensure it is properly tracking the path of the sun.
The Cooperative’s Net Metering equipment
cannot detect if your system fails or is operating
at a reduced efficiency. If your system does not
record your panels’ kWh production, we
recommend you request a meter be installed to
help you monitor your system. This can be done
by your installer or a licensed electrician.
It is up to you to know if your panels are working properly.
Investing into solar energy can be an empowering endeavor. The
Cooperative wants you to have all the information you need to do it
properly and keep it going.You can also read
