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 PV Arrays
(Solar Panels)
1. Check to make sure all
panels are attached properly to their mounting brackets and nothing
obviously catches the eye as being abnormal.
2. Visually inspect the array
for cracked modules.
3. Open each combiner box and
test open circuit voltage and short circuit current (if possible).
Recheck torque on any screw terminals.
4. At final array breakers repeat
open circuit voltage and short circuit current tests (if possible)
to be sure that all array wiring is properly connected
5. Perform
dry insulation test, at test voltage of 500 V, on array and array
wiring. (note: disconnect all SOV's and MOV's BEFORE doing insulation
test).
6. Check for NEC type marking/label
on the modules. NEC 690-51: Modules shall be marked with identification
of terminals or leads as to polarity, maximum overcurrent device
rating for protection, and with rated 1] open-circuit voltage,
2] operating voltage, 3] maximum permissible system voltage,
4] operating current, 5] short-circuit current, and 6] maximum
power. See NEC 690-52 for ac module requirements.
Wiring
1. Check
exposed array wiring for rating and sunlight resistant insulation.
2. Check
from the ground to see that all wiring is neat and well supported
to stay in place.
3. Check that strain reliefs/cable
clamps are properly installed on all cables and cords by pulling
on cables to verify [NEC 300-4, 400-10].
4. Make sure that all grounded
conductors are white and equipment grounding conductors are green
or bare [NEC 200-6(a), Ex 5].
5. DISCONNECT ALL MOV's and
SOV's, if any, then perform insulation test on system wiring.
Use a test voltage of 500 V for all wiring 600 V and below.
6. Check that all field wiring
are tagged at both ends with permanent wire markers.
Wiring
Methods
1. Flexible metal conduit
is generally suitable for installation in dry location. Check
that supports are no more than 12 inches from boxes (junction
box, cabinets or conduit fitting) and no more than 54 inches
apart [NEC 350].
2. Liquidtight Flexible Metal
Conduit is generally suitable for installation in wet and dry
locations. Check that supports are no more than 12 inches from
boxes (junction box, cabinets or conduit fitting) and no more
than 54 inches apart [NEC 351].
3. Liquidtight Flexible Non-Metallic
Conduit is generally suitable for installation in wet and dry
locations. Check that supports are no more than 12 inches from
boxes (junction box, cabinets or conduit fitting) and no more
than 36 inches apart [NEC 351].
4. PVC is not intended for installation
in locations subjected to direct sunlight.
5. Long
straight conduit runs, 100 feet or more, shall have expansion
fittings.
Charge
Controllers
1. Retorque all terminations
2. Check that all voltage settings
are properly set for the appropriate battery type or system configuration.
3. If
the system is connected to a utility-interactive inverter, make
sure that the settings of the charge controller(s) do not interfere
with the proper operation and dispatch of the inverter system.
(note: If charge controller set points are used to regulate the
float voltage of the battery rather than the inverter, power
will be wasted from the PV array at the charge controllers before
it can be made available to the inverter or battery.)
4. Verify
that charge controller operation matches the programmed settings
by forcing the system to the set points and making sure that
the unit performs the proper control function.
Disconnects
1. Retorque all terminals
on disconnect switches.
2. Check voltage drop across
switches while operating.
Batteries
1. Retorque
all battery connections.
2. Coat
each terminal with anticorrosive gel.
3. Make sure that access to
terminals is limited [NEC 690-71(b)].
4. Make sure that location provides
adequate natural ventilation (well vented areas like garages,
basements, out-buildings, not living areas).
5. If battery contains flooded
cells, top off cells with distilled water according to the manufacturers
instructions.
6. If battery contains flooded
cells, be sure an eye wash station is accessible.
7. Once inverter is operational,
equalize charge the battery to ensure that the battery is properly
connected and functioning properly.
8. Ideally, the installer should
run the battery through a few heavy charge-discharge cycles to
exercise the battery and potentially cause infant mortality in
a defective new battery.
9. Check individual cell or
battery voltages after equalization
Inverters
(Utility-Interactive Systems)
1. Double-check inverter
manual to verify that the array open circuit voltage is acceptable
to the inverter.
2.
Check utility line voltage to verify that it is within the proper
tolerances for the inverter. If line voltage is above 127 Volts
ac before starting the inverter, verify that the maximum voltage
drop for the inverter output circuit is less than four volts.
(Reason: IEEE 929 requires that the inverter not operate above
132 Volts ac. A larger voltage drop could cause the inverter
to shut down on overvoltage.)
3. If inverter measures and
reports utility or inverter ac voltage on a display, verify that
this voltage agrees with a high quality, true-RMS ac volt meter.
4. Retorque
all electrical terminal connections in the inverter to tighten
any connections that may have loosened since the initial installation.
5. Follow inverter starting
procedure as printed in the owners manual.
6. For non-battery-based inverters,
once inverter has started and is operational, check to see that
the maximum power point tracking (MPPT) circuit is operating.
This should be done during clear sky conditions if possible by
monitoring array voltage from the open circuit condition until
it reaches a point where system power peaks and then starts to
drop again. Keep monitoring voltage until you note that the system
voltage has been adjusted up and down several times.
7. Verify that the operating
voltage is near the expected peak power voltage for the conditions
of the test (this can be found in most manufacturers literature).
If inverter has manual voltage control, move inverter voltage
through expected maximum power point voltage to verify actual
maximum power voltage and proper operation of MPPT circuit.
8. For battery based inverters,
use the programming features of the inverter to charge the battery
and then dispatch the battery to the utility grid to ensure that
these functions are operating properly.
9. Check
the programming of the inverter to be sure it is set up to operate
at the proper voltages for the chosen battery. Inverter should
be programmed to perform the constant voltage charge control
rather than the charge controller.
10. Temperature compensation
probe must be connected to control battery voltage properly.
11. Instruct the homeowner on
what to do in the event of an inverter failure.
Grounding
1. Verify that only one connection
to dc circuits (ungrounded conductor) and one connection to ac
circuits is being used for system grounding [NEC 250-21] (referenced
to the same point).
2. Check
to see that equipment grounding conductors and system grounding
conductors have as short a distance to ground as possible and
a minimum number of turns.
3. Check that non-current carrying
metal parts are grounded properly, note that terminal lugs bolted
on an enclosure's finished surface may be insulated because of
paint/finish at point of contact is not properly removed.
4. Check resistance of grounding
system to earth ground, NEC allows 25 ohms or less.
Safety
Signs
1. any
fuse or circuit breaker that can be energized in either direction
must be labeled as such. [NEC 690-17]
2. Interactive Point of Connection
for interactive PV systems. [NEC 690-54]
3. " A sign shall be placed
at the service-entrance equipment that indicates the type and
location of on-site optional standby power sources." [NEC
702-8]
4. Provide any additional information
that you think would be helpful to the homeowner, inspector,
or fire officials.
 Grid-Tie Basics
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