TESTING I CASE STUDY
find a portable but capable test system that would document the performance of each module in a recordable way.”
Knowing the outcome is vital Recently Comet was offered a container of 170W used monocrystalline solar panels and used them on a 12 kW commercial flat roof top system.
These PV units had been replaced on their original system due to yellowing of the backing but were in perfect electrical and mechanical condition. As the modules were used, Comet tested every unit prior to installation to make sure of the quality and safety of the modules and also to prevent any subsequent dismantling of the installation for any troubleshooting required.
To do this Comet set up an improvised test bench at the installation site and tested every module as it came out of its packing. All testing was carried out during the middle of the day so as to make use of full sun for testing. Every one of the 66 modules were tested individually and no issues were found, with all units performing as expected with little variation between the modules and no ground faults or open circuits.
Importantly, the speed of the test system allowed comet to perform full tests on each module without impairing the workflow of the installation crew. The test data for each module was downloaded and given to the owner as a system spreadsheet to reassure him that testing had been carried out thoroughly to verify the quality of the modules and to confirm the anticipated performance levels of the system.
Building on experience
Comet’s latest solar PV installation project is much larger and so requires a different test regime. The company is currently installing 500KW of Canadian Solar 240W modules, purchased directly from the manufacturer.
As these are Tier 1 Grade A modules, Comet won’t be pre-testing every module, but will test each string at the combiner before installing fuses.
Working to US NEC requirements does not does not allow for easy testing of the installation in the way that typical UK systems do. The wiring is always in conduit and the combiner circuits are hard wired, so there is no easy way to test installed strings on larger systems.
For these larger projects, Comet will therefore be using 1000V rated test leads with alligator clips. Chris Mason said: “Using the PV150 system on an installation in front of the client gives a sense of security that the installers are professional and are doing the project properly.
“We are seeing the emergence of some less than professional installers in the region who perform poorly crafted installations, test nothing and do not give the customer any comfort that the work is being done properly.
“We invite our customers to witness the commissioning tests with the PV150 so they can see how much work goes into our quality assurance procedures. This is both a marketing tool to enhance word of mouth referrals and protection against liability from call- backs.
“Documenting system performance at commissioning gives us a baseline against which to retest in the case of a complaint or problem, both with customers and manufacturers. For this use alone, the test kit and reporting system is invaluable.”
©2013 Permission required. Angel Business Communications Ltd.
Issue III 2013 I
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