Array diagram
One-line electrical drawing
Three-line electrical drawing
Identification of the main system components
PV array
DC combiner box and type
Conductor and conduit types and sizes
Electrical boxes
Inverter type, size, and location
Critical load subpanel or AC combiner panel, if applicable
Utility disconnect
Main service panel (SES)
Utility service access
All required meters, switches, and overcurrent devices such as breakers
or fuses
Code version designed for the system and appropriate citations
and labeling
Structural and wind load calculations
For standalone PV systems with battery backups or hybrid PV systems, a list
of the energy storage device, size, capacity, and electrical drawings of all
details of batteries, wind turbines, etc.
Maps of all important electrical parts and equipment
Completed utility contract
Illustrations of the complete PV structure, especially if the system is fused to
another building
A list of measurements for all the components
PV System Installation
There are many important aspects of installing a PV system. Proper installation is
vital to creating a well-performing PV system. Proper design and installation is
the key to great performance. But as you read in Chapter 1, current studies show
significant installation problems in large numbers of PV systems.
Basic Steps
Before starting, determine the appropriate equipment for the system and the tools
for completing the installation. When ordering the equipment, you should take
into consideration the delivery time for various components and provide enough
time in the schedule to have everything ready. When the equipment arrives, make
sure nothing is broken. You also should complete a walk-through with the cus-
tomer or customer’s representative, and have the customer sign approvals for all
installation locations. Make sure that they understand what you are installing and
where it is being installed. Don’t forget to discuss possible drawbacks. Finally, read
CHAPTER 3 Installation: Creating the Best PV System 53
through the owner’s manual for each piece of equipment.
Make sure the plan does not cause a conflict with warranties
or component design.
Wiring
When you are ready for wiring, calculate wire lengths from
the PV arrays to the combiner and inverter. Select the correct wire size, as per
NEC requirements, and upsize for a 1 percent or less loss for a high-performing
system. Use maximum overcurrent calculations for each circuit as the basis for
wire size, and double-check for accuracy at the site. (A circuit consists of the wire,
switches, fuses, etc., that attach the load to the power source. The load is the
amount of energy used by any electrical appliance at a given time; or sometimes
the appliance itself is referred to as a “load.”) You must always double-check the
ampacity for array circuits. This also includes checking for the ampacity range for
module-to-combiner wires.
Label the maximum fuse rating. You should always run wires at least 25 feet
between modules to the combiner. Make sure the wire length from the combiner
to the inverter is at least 75 feet. Then calculate the wire distance between the
inverter and main service panel.
PV Components and Batteries
The following basic steps should be taken when installing PV components and
batteries:
1. Make certain the main service panel bus bar is of sufficient size and rating to
house the PV breaker and PV load.
2. Purchase and install a new main service panel, and downsize the main
breaker, if appropriate, or the PV system.
3. Determine which circuits are critical in PV systems that have a critical load
subpanel (battery standby system).
4. Check to see if multi-branch circuits can be wired to 120 VAC standby
systems.
5. Look at the loads connected to the standby power system to see if the system
can handle the actual power consumption and daily usage in standby mode.
6. Connect the standby power systems into a separate subpanel from
the inverter.
7. Measure the standby system’s energy usage.
8. Figure out the battery capacity for uninterrupted power.
9. Choose a storage battery system that meets the customer needs and also has
maintenance-free batteries with absorbed glass mat (AGM) construction.
10. Do not use untested batteries.
11. Place battery cabinets in a cool place away from the sun.
TECH TIPS
Pay close attention to wire size.
Smaller wires may cause voltage drops.
54 ADVANCED PHOTOVOLTAIC INSTALLATIONS
12. Remember to ventilate batteries to the outdoors.
13. Provide battery spill containment for the system.
PV Arrays
PV arrays are delicate and heavy. You
should handle them very carefully. Here are
some of the basic steps required to install
PV arrays properly:
Prepare structure for mounting of PV
array on the ground or roof.
Use manufacturer’s recommendations
to mount arrays on the roof and for
torquing foot-pounds.
Inspect every module before placing
them onto the array.
Use plug connectors to connect
panels together.
Remember to only use attachment
points and roof penetrations (from the
PV system drawing).
Set PV panels into support structure
and secure.
System Connection to Utility
Once the wiring, PV components, batteries, and arrays are ready, it is time to
install and connect them all together. Then you can connect the PV power system
to the utility grid.
1. Install the combiner and inverter in place for system wiring.
2. Join module circuits, and wire the circuit to the combiner.
3. Connect the disconnect switch (used to join or disconnect mechanisms
within a PV system) and circuit combiner with wire.
4. Wire the disconnect switch and the inverter to one another.
5. Join the main service panel and utility disconnect switch
with wire.
6. Hook the main utility service to the main circuit.
7. Check that circuits are working as anticipated.
8. Go through the PV System Installation Checklist (see
Chapter 1).
9. Review the System Acceptance Test for operational
standards.
TECH TIPS
Standby systems are covered in
National Electrical Code (NEC) Article 702.
TECH TIPS
Check the circuit combiner to
make sure all the circuits are terminated
and torqued properly. This needs to be
done before connecting each string at
the array end of the circuit.
Improper handling of panels can result in cracks. Cracked panels
cannot be used and must be replaced. This can be an expensive
installation mistake.
Courtesy of PerfectPower, Inc.
CHAPTER 3
Installation: Creating the Best PV System 55
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