Determining the Array Location
You need to install PV arrays in shade-free locations. PV arrays are groups of
linked PV modules. PV arrays should be shade free between 8 a.m. and 4 p.m.
Even a small amount of shading on the arrays can significantly impair their output.
Complying with Relevant Codes
As a PV professional, you should know the latest National Electrical Code (NEC)
guidelines related to PV systems. You should also be familiar with national, state,
and local building codes pertaining to PV systems. Check the electrical and
building codes in the customer’s city, county, and state. Also, determine whether
any covenants in the customer’s neighborhood association
documents or other restrictions apply to PV system installa-
tion. Then ensure that your PV system design complies with
all the applicable codes.
You will likely have to fill out several forms and applica-
tions to get approval for a PV system design. Submit the PV
system design plans to the authority having jurisdiction
(AHJ), the local building or electrical inspector that signs off
on PV system permits and installation. Processing times vary
in different cities and states. After the system is installed, the
AHJ will also need to inspect the PV system for compliance.
Minimizing Electrical Losses
Pay close attention to electrical loss when designing and installing a PV system.
The placement and connection of wiring, fuses, switches, and inverters can cause
electrical losses and waste electricity.
You want a system to have as little cable loss and voltage drop as possible. The
NEC requires sizing wire to a 1 percent wire loss or less. Wire loss is the loss of
NOTE
Complying with applicable codes
does not necessarily ensure a higher-
performing PV system. A system can
meet codes and still not work very well.
However, NEC guidelines and other
building codes are legal requirements
for protecting health, life, and property.
Compliance is not optional.
CALCULATING THE SHADE AT A LOCATION
Many PV system designers and installers mistakenly calculate the shading only for noon on the
winter solstice and shortest day of the year (generally around December 21). This method can
result in rows of panels being placed too close to each other or being sited too close to other
shade objects. Either problem can mean weeks to months of partial shading on panels. A better
approach is to calculate the shading during the window from 8 a.m. to 4 p.m. on the winter
solstice.
4 ADVANCED PHOTOVOLTAIC INSTALLATIONS
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