Page 26 - Issue 4 2023

TECHNICAL

electrical production. It’s very important One reason could be hot spots, the accumulation of current and heat on a short-
for a module to have the electrical circuited cell, leading to reduced performance and possible fire. Thermal imagers like the
characteristics specified, because an Fluke Ti480 PRO Infrared Camera or the Fluke TiS75+ Thermal Camera can quickly identify
inverter has a minimum and maximum hot spots.
input current, below and above which it Ground faults are another, but they’re harder to diagnose and require testing the
will have no power output. voltage and current of each conductor and the equipment grounding conductor (EGC),
which carries stray current to the ground. Voltage and current on the EGC indicate a
Scenario 1: Open circuit voltage or short ground fault. Ground faults can occur due to damaged conductor insulation, improper
circuit current is higher or lower than on installation, pinched wires and water, which can create an electrical connection between
the datasheet a conductor and the EGC. Find the source of the problem and replace the damaged wires
In this case, the string has one or more or improve the conditions.
modules whose characteristics don’t Other reasons for low power output could be shading and poor tilt and compass
meet specification. Open circuit voltage direction (azimuth angle) for the location. Use a solar pathfinder to find any new sources
out of range means the inverter may not of shading and remove them, if possible. While it may not be feasible to change the tilt
output power. Short circuit current out of and compass direction of the array to point the panels more directly toward the sun, you
range indicates there may have a module should know the tilt and azimuth angles to establish a baseline for future reference.
mismatch, which can severely degrade In large-scale PV systems, the power from a solar system goes through transformers
the array’s performance, because the after being inverted to step up the voltage, then to switchgear and medium voltage cables
current of a string is limited by the where decreased insulation resistance is a common issue. For medium and high voltage
module with the lowest current. Identify cables, use the Fluke 1555C FC 10kV Insulation Tester, which can test up to 10 000 V.
and replace the modules. For systems with batteries, compare the expected battery voltage and state of charge
with the actual, using the Fluke 500 Series Battery Analyzer.
Scenario 2: Power output is low
If the power output is lower than Contact Comtest, phone 010 595 1821, sales@comtest.co.za, www.comtest.co.za
expected, there may be a problem. While Facebook: bit.ly/3iuk4cg
some fluctuation in output is expected, YouTube: bit.ly/2V4nc6j
consistently less than predicted output LinkedIn: bit.ly/3rpTu86
could be a sign of a faulty string, a ground Product: https://bit.ly/3I5bb70
fault, or shading. Hash Tags: #Comtest #Fluke #Solar #Photovoltaic #Renewableenergy

V2 12975 Fluke IRR SOL PV Commission

26 | energize Issue 4 | 2023 SUBSCRIBE FREE