Solar Photovoltaic Panels
Technology Snapshot & Benefits:
Solar photovoltaic (PV) panels make use of photovoltaic technology to convert
sunlight into usable electrical energy. Each panel is made of a collection of
photovoltaic cells that each produce between 1 and 2 watts of energy. A typical
cell consists of a glass layer on top of an antireflective surface (to prevent
the sunlight from reflecting back into the atmosphere) and two semiconductor
layers (typically made of silicon) surrounded by metallic grids or electrical
contacts. When the sun's light hits the semiconductor layers of the panel, it
knocks electrons loose. Because of the electrical field on the panel, these
free electrons are moved to the top of the grid where the electrical contacts
gather them into a direct current. With the use of an attached inverter, the
direct current is converted into alternating current (the form of energy used in
electrical outlets). PV systems are used for
"off-the-grid" applications (homes, cabins, and water pumping on farms) as well
as federal government applications (traffic warning lights and emergency call
boxes near highways).
Solar panels serve an important function by creating an alternative source of
electricity and reducing dependence on coal. Because they generate electricity
without any moving parts, require little maintenance, and emit no harmful gases
or chemicals, they are becoming one of the best ways to reduce the carbon
footprint and help the environment. Also, the more energy-efficient your home
is, the fewer panels are needed to power it. Consider implementing smaller
green renovations (CFLs, better insulation, energy-efficient appliances and
windows, etc.) before installing solar panels. This will minimize your upfront
costs by reducing the number of panels you need as well as decreasing your
monthly energy expenses.
Estimated Cost Savings:
While solar systems are still relatively expensive, the price has come down
significantly since they were first produced. Currently, a typical solar system
can cost anywhere between $5,000 and $100,000 depending on how much energy you
wish to produce and how large of a space you are powering. Starter kits, which
usually consist of one panel, a battery, an inverter, and the necessary cables,
start as low as $500-$1,000, but only generate a limited amount of energy.
Individual solar panels cost anywhere from $50 to $1000 depending on how much
energy they produce and the material they are composed of. The lower-range
models are typically used for recharging electronics batteries (phones, iPods,
etc.), but will not produce nearly enough energy to power a house. In addition
to the panel itself, initial expenses include balance-of-system costs such as
batteries, charge controllers, inverters, support structures, sensors,
installation, and insurance fees. Solar energy currently costs between $3 and
$4 per watt (15-25 cents per kWh), creating a 10-20 year return on investment.
Solar panels are ideal for remote locations where it is more expensive to
connect to the power grid as the monthly monetary savings will be more dramatic.
For a truly "off the grid" installation, the avoided cost of bringing in power
lines from the utility offsets some or all of the PV installation cost. An off
the grid installation uses batteries to store electricity for use at night and
whenever sunlight cannot provide enough for the home.
Check for financial incentives offered in your state by consulting
Database of State Incentives for Renewable Energy.
Because solar panels need sunlight to function properly, their efficiency
depends on weather conditions, obstructions, and their position and angle
relative to the sun. To maximize efficiency, remove any branches, trees, or
other obstructions that shade the panels. If possible, place the panels on a
south-facing roof at the
recommended angle for your latitude.
Dynamic mounts are available that alter the angle of the panels throughout the
day to follow the sun, allowing for the greatest amount of direct light
Weather conditions may also affect the efficiency of your solar system.
However, even on cloudy days, there is still enough indirect light to generate
limited amounts of power. The panels will continue to generate energy
throughout the winter as they rely on light not heat. However, because the days
are shorter during wintertime, they will generate proportionally less energy due
to a shortened exposure to sunlight.
Water damage is one of the biggest problems regarding solar panels as it causes
the panels to decrease in efficiency or completely malfunction. To avoid this
problem, do not mount your panels horizontally as this will cause water to
collect and may cause serious damage. Also, make sure there is a sufficient air
gap between the panels to allow for drainage and ventilation.
It is possible to connect your solar system to a battery to ensure your home is
powered through the night and any power outages. Batteries can store the extra
electricity generated throughout the day and keep it on reserve for later use.
Installation (Getting It Done):
Some solar panels can be installed yourself, but many manufacturers suggest
professional assistance to ensure it is placed in the best possible location.
When installing, remember that solar panels use light to produce energy, so it
is important to place them in a location that receives direct sunlight
throughout the day. A south-facing roof is usually the best option, but an
east-west roof can work as well. If you have a large ground area without
obstruction, a ground-mounted system may work for you. Be sure to remove and
obstructions when installing to ensure your solar panels are able to work at
their maximum capacity.
Remember that a 1 kW solar panel requires between 80 and 360 sq. ft. of space to
install and a typical home system requires between 50 and 1000 sq. ft.
There are a few types of mounts for solar panels including pole mounts,
roof/ground mounts, and flush mounts. These make it possible to mount your
system on a pole or roof, as a free-standing system, or even on the top of an
RV. Dynamic mounts can also help provide maximum energy capture by following
the position of the sun throughout the day.
If you are installing solar panels on an older roof, it is recommended that you
replace your shingles before installation to help provide better support for the
Videos On This Topic:
From EcoBroker International:
From Other Sources:
Economics (1:17) - Sierra Club Green Homes -
If you can't
afford solar technology at this point, consider looking towards simpler
solutions to help reduce energy use. In this short video, Chris Prelitz of
NewLeafAmerica.com gives a simple, inexpensive solution that saves the same
amount of energy as one solar panel.
Solar Basics for Your Home (1:05) - Rethink Solar Power -
Solar panels work
through the use of photovoltaic energy. Find out how this technology works and
what it can mean for your energy bills in this short video.
Solar Power (2:39) - National Geographic Green Homes -
The sun is the
number one source of energy on our planet. Harnessing its energy for home use
is a great way to save money and reduce environmental impact. In this video from
National Geographic, find out more about solar technology and what it means to
install it in your home.
Explanation of Solar Cells
(1:15) - U.S. Department of Energy -
centers around solar cell technology. To understand more about what that means
and how it works, watch this short video from the U.S. Department of Energy on
On This Topic:
U.S. Department of Energy's Office of Energy-Efficiency and Renewable Energy:
Department of Energy's Office of Energy-Efficiency and Renewable Energy:
Energy and Environmental Building Association: Photovoltaics
EPA - Solar Panel Information
Solar Panel Info - About Solar Panels
U.S. Department of Energy - Putting Solar Panels on Your Roof
Solar Panel Incentives By State
How Solar Cells Work