Residential Solar Energy: Sunlight Hours, Light Reflection, and Sun Angles (Part 6)

Throughout most of the United States, the averageaccount the total amount of energy required per
homeowner can expect 4 or 5 sun-hours per day.month and per year then average out to the highest
This is true even in rainy Seattle and most of Alaska.electric needs on a monthly basis. All of this data is
Each of these locations still receive about 3 or 4included with the solar energy sizing estimates.
sun-hours per day. This means, of course that moreThere are single axis tracking solar systems that track
panels are needed to cover consumption but solarthe sun from east to west. There are also dual axis
generated electricity is still possible.tracking solar systems that track both from east to
There is encouraging information for thosewest and up and down, following the sun's altitude and
homeowners who live in areas of the country coveredazimuth to optimize production throughout the season.
with snow or, clouds due to frequent storms, for muchIn the winter, the sun is much lower in the sky than in
of the year. The following article explains in some detailthe summer therefore solar energy systems that can
how how the sun angle effects solar energy out put intilt up or down have a greater chance of catching all
the form of electric for home solar power units. Weof the sun's energy.
will also document a few of the common componentsForms of Sun Irradiance
in a home solar energy system such as mounting units,The sun reaches the solar panels in various paths, not
sun tracking systems, and more.just directly from a sun's beam being directly overhead.
The Sun's Irradiance Throughout the DayBecause of this fact, there may be good generation of
Many graphs and charts, found on the Internet viasolar electricity on even overcast days or when you
searching, show a solar cell module's output when itwould not think the sunlight is of proper intensity.
faces south throughout the 4 days following the fallThere are three types of irradiance. 1. Diffuse
equinox. These graphs most often show a bell curveIrradiation: Scattered light comes from the whole sky.
of the power output, where peak production occursDiffuse light from the sun does not exist on blue sky
around 12 to 1pm with a morning ramp-up and adays where there are not clouds. On the other hand, it
decline as the sun goes down. This is due to intensityis found a lot in areas of smoggy or cloudy weather.
of light as well as deflection. As the days get shorter,2. Direct Irradiation: A beam of sun light goes straight
the total irradiation falls as expected. The sun no longerfrom the sun to the solar module and directly interacts
is directly square with the panels, since it is lower in thewith the solar cells
sky.3. Reflected Light (i.e. the Albedo effect): This is light
Panel Tracking Devices for Home Solar Energythat is reflected or scattered by the ground or nearby
Systemssurfaces like trees or other buldings. Snow gives off a
The best way to get around this decline in energylot of this albedo light and grass or dirt gives off very
output is to place the solar array on a tracking devicelittle.
to keep it in direct sunlight for more time throughout theSun Path Diagrams and Home Solar Energy Systems
day. Looking at a sunflower can give you a good idea.A sun path diagram plots the position of the sun
The sunflower wakes up in the morning facing duethroughout the year. This is very useful when designing
East to catch the morning sun. As the day progresses,and installing solar arrays, to optimize the performance
the sunflower turns its head to track as much sunlightby determining the best angle and to avoid shadows
as possible. It's perplexing why sunflowers grow so tallfrom trees, vents, other buildings, etc. Understanding
and sturdy? They soak up as much sun as possible.where the sun traces across the sky at your home,
There are two different types of tracking systems forallows you to place your solar energy unit in the
residential solar energy units. Often there are alternatecorrect location. You can also determine if you may
methods to mount a solar array. You could mount theneed to supplement your solar power system with a
solar panels on a fence, a flat wall, on a light pole, buttracking device.
the methods that follow are the most common.Expanding Options for Residential Solar Energy
The level, horizontal mounted array produces moreNew solar energy technology is continually coming to
energy in the summer when the sun is directlymarket that takes the idea of solar power to a new
overhead.and simpler levels. Homeowners, while it is very useful
2) Fixed angle at the optimum tilt angle yields the mostto know the nuts and bolts of solar power systems,
kWh for a fixed array over the course of the entiredo not have to know the level of detail as presented in
year.this article. New solar technology and home solar panel
These two types of tracking systems createrental services provide energy efficiency and better
dramatically more exposure and higher sun hours allcontrol of power consumption. These solar power
year long, but still more in the summer months. Thisrental programs enable electric services that are more
relates to the overall need to calculate and take intoresponsive, more reliable, and more renewable.