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reference is the American Wood Council's National Design
Specification for Wood Construction (NDS). This reference
provides a method for determining the “pull-out” capacity of
lag bolts in different species and grades of wood.
Near the end of the SolarPro magazine article, it says:
“Modern structures are built with factors of safety large
enough to account for the relatively small loads imposed
by a PV array. For older buildings or those built with
nonstandard construction practices, however the
structural members should be evaluated to ensure
structural integrity.
0
If a roof structure on an existing residential building is
deficient, most
authorities having jurisdiction
require
that the roof structure below the array be brought up to
current building code.”
Rebates and Incentives (Programs)
It is important to research the requirements for qualifying and
applying for rebates and incentives. Many utilities have
programs but certain requirements must be met to qualify.
The website at
www.dsireusa.org
is a useful resource for
researching federal and state incentives and getting
information on programs offered by electric utilities.
Examples of types of rebates and incentives are listed
below:
1.
System output (either in DC or AC watts).
2.
Performance-based -- Rebate levels are awarded based
on the predicted output of the system, given the
characteristics of the actual installation.
3.
Tax credits for a percentage of the installed cost of the
system are widely available through both the federal and
state governments. The federal tax credit for solar
renewable energy applies to the solar components of the
SunSource
®
Home Energy System. This includes the
AC solar modules, solar sub-panel kit, roof mounting kits
and all other labor and components needed to install the
solar portion. The credit is in effect through 2016 and
allows for a credit of 30% of the installed cost of the solar
system. The credit is uncapped. For more information go
to the Department of Energy tax credit website at:
http://www.energy.gov/taxbreaks.htm
or the Energy Star website at:
www.energystar.gov/index.cfm?c=tax_credits.tx_index
4.
Some states and local governments have enacted laws
that will NOT allow the tax assessment of a property to
be increased because of the addition of a renewable
energy system. Property Assessed Clean Energy
(PACE) programs are available from some governments
to provide financing for the installation of a renewable
energy system that is paid back, with interest, in the
homeowner’s property tax.
Site Evaluation
GENERAL
On earth, the energy available from the sun is about 1000
watts per square meter. A solar module converts about 14%
of that energy to electricity. For a fixed-orientation module,
the peak available energy occurs in a clear sky with the
module directly facing the sun. Throughout the day, the
angle that sunlight hits the module changes as the sun
moves across the sky. Because of this, the available energy
rises to a peak daily value and then declines. There is also a
seasonal variation: The sun is lower in the sky in winter and
higher in the sky in summer. The more closely that the tilt
angle of a solar module matches the local latitude; the more
optimized the annual energy output will be.
Compromises are frequently involved in locating and
installing solar PV modules. Homeowners may wish to have
the module located in a sub-optimal location/orientation for
esthetic reasons. This system is designed to be installed
parallel with the roof pitch (see Appendix A). The pitch of the
roof will determine the tilt of the solar modules The
orientation of the home itself may dictate the direction the
solarmodules face.
Figure 6. Orientation
