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Green Collar Careers - Solar
Electric System Configuration
Where there are some similarities between configuring solar heating
and PV systems, there are some differences in the configuration rules.
Like the solar heating system, the best pricing will come on a kit
from a retailer sized to the application needs. Some key
differences are in the mounting, cabling and lightning protection
requirements. These systems are very different in how they are
constructed. Solar PV Panels tend to take a little more
maintenance over the years. The glass should be cleaned every 6
months or so depending on the environment. Oily films, bird
droppings, even tree sap may build up reducing the transparency.
Ozone rich air may tend to corrode connections, ever with the sealed
connections compliant with NEC standards. Other then cleaning
most solar PV Panels will last 7-15 years before corrosion becomes a
problem, and at that only 1 in 5 systems may ever have those problems.
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PV Panels should be kept out of the elements as much as possible
and ALWAYS out of exposure to the sun. Systems that have
been installed on roof tops more then 5 years ago are beginning to
show there age. Earlier connectors began to corrode, wiring
exposed to the sun may have cracks in the hardened insulation, and
mounting structures have loosened. Amateurs mount solar
panels on the roof without consideration of a 25-30 year life.
Most of the solar PV systems you see have the
panels mounted to the roof but take a closer look; while you
may compromise the optimal angle for a solar collector, you want
the solar PV panel to be pointed much more accurately. It
the pitch of the roof and facing angle isn't' just right, it just
doesn't look right.
One of the cleanest mounting arrangements for
solar PV panels are awnings over south facing windows. This
allows easy access and provides shade for the windows from the
summer sun.
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Ground mounted solar PV systems are the most
economical way to mount the panels and provide the easiest access.
This system is rated at 4000 watts and takes up a footprint of 6'
x55'.
Configuration Rules
- Grid-Tied systems require contacting the utility provider to
determine any special requirements for the system. In most
cases the inverter, grounding plan, disconnects, surge
protectors and circuit breaker ratings will need to meet their
specifications. In addition, most utilities will want a
separate meter that measures only the solar PV production so
they can discount any electricity that you sell back to them.
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- Local electrical codes may apply to the wiring
and placement of inverters and disconnect switches. Contact
your local city government building inspector and inquire.
- Grounding and lightning protection cannot be stressed enough;
just because local code may not require a well grounded system
doesn't mean it doesn't need to be well grounded. Use at least
a 6 foot grounding rod with a 1/0 cable to the mounting structure,
DC and AC disconnects and the Main AC power panel unless otherwise
instructed by the utility company.
- Solar Panel Mounting Hardware should be a rigid structure with
squared up 4-point mounting to the solar panel frame that does not
twist or stress the panel.
- Underground cabling or cabling exposed to sunshine should be run
through conduit.
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