Handle PV arrays with great care during installation; do not step on them or
place heavy objects on them. Pay special attention to sharp edges and corners of
panels and metal mounting hardware.
Array Interconnection
Connecting the PV arrays together requires attention to many details. Attention
to these details provides a safe work environment and the additional assurance of
a correct installation. As with any project, measure twice and cut once. All the
arrays on a given system inverter should be similar, of the same type of slope or
orientation. Connect arrays with touch-proof fuses.
Remember that PV arrays produce power during the day and in strong artifi-
cial lighting. Trip the circuit breaker to open the circuit if you need to disconnect
CHECKLIST NO. 4: SYSTEM ACCEPTANCE TEST
Personal protection equipment is recommended here, too.
Ensure that PV array is without shading and gets full sun.
Turn the system on for fifteen (15) minutes before capturing any PV system
performance data.
Take solar irradiance measurements. (To obtain percentage of peak sun, divide irradiance by
1,000 W/m
2
.)
Method 1: Use a pyranometer or attuned solar meter.
Method 2: Set an individual PV array in full sun at the exact same orientation as the
array being tested.
Expose the array for fifteen (15) minutes and test the short circuit current. Use a
digital multimeter.
Divide the number by short circuit current (Isc) value on the back of the PV array.
Multiply this number by 1,000 W/m
2
. Example: If the measurement = 3.6 Amps and
Isc = 5.2 Amps, irradiance = 3.6 Amps/5.2 Amps × 1,000 W/m
2
= 692 W/m
2
Add up the all the array ratings and multiply by 0.7 to get the projected peak AC output.
Calculate the output from the inverter or system meter.
Divide the projected AC output by the calculated output from the inverter. This value is the
rated output of the PV system. It needs to be within 90 percent or higher of the projected
AC. If it is less than 90 percent, the PV system is not operating at peak performance. Check
for shading or leaves on the arrays. Also, reexamine the wiring and fuses.
14 ADVANCED PHOTOVOLTAIC INSTALLATIONS
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