assess pre-engineered system designs. Alternatively, you may use them to compare
system features from one supplier to another.
Materials Recommendations
Use PV system components made of sunlight/ultraviolet (UV)-resistant mate-
rials. Seal the seams for all non-flashed roof cracks with flexible urethane sealants.
Be sure to work with materials appropriate for local temperatures and weather.
Use non-conductive shims or washers to isolate different metals, such as steel and
aluminum. Use high-quality stainless steel fasteners.
Structural parts should be corrosion-resistant aluminum and galvanized
steel. You can use coated or painted steel for desert climates, but you need stain-
less steel for coastal environments.
Recommendations for Equipment and Methods of Installation
Accurately list the voltage and current rating needed and used on all electrical
equipment. Make sure all your PV arrays have at least five-year warranties and are
listed to the Underwriters Laboratories standard known as UL 1703. Inverters
need to be listed to UL 1741 and have service guarantees for at least five years. Use
sunlight/UV- and moisture-resistant listed conductors. Keep
all conductors in conduit, or else provide other light protec-
tion for light-exposed areas.
Overcurrent protection should be easily accessible for
maintenance and testing. All electrical terminations must be
tightened, secured, and strain-relieved as needed. They must
be torqued properly in line with NEC requirements. Install
mounting equipment and always torque mechanical connec-
tions according to manufacturer specs. When sealing roof
cracks, take care not to damage the roof or void the roof war-
ranty. Use Class A roofing products. PV arrays should be free
of shade between 8:00 a.m. and 4:00 p.m.
PV System Installation, California Style
The following checklists are adapted from the California Energy Commission’s
Guide to Photovoltaic (PV) System Design and Installation. Although the guide
was developed for use in California, you will find it applicable across a wide range
of installations. These checklists will help you make sure you complete all aspects
of an installation. They will also help you document your work. That’s important
in establishing and following a quality-assurance process. As you read earlier,
proper installation is the key to top performance. The main purpose of the check-
list is to simplify the installation of safe, high-performing PV systems by reducing
TECH TIPS
You should secure all cables,
conduit, exposed conductors, and
electrical boxes and support them
according to code requirements. For
better systems with lower maintenance
and a longer life, use metal ties and
clips for securing PV panel cables, and
never expose the insulated conductors
to sunlight.
10 ADVANCED PHOTOVOLTAIC INSTALLATIONS
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