Installation inspection – Shopping centre

Cleaning, Maintenance, Solar PV

With the original PV installer 'Conergy' closing down their UK operations, NWT Energy were invited to inspect their installation work and oversee any necessary remedial works prior to the release of their project retainer. Ensuring that the overall quality met the requirements of the original CDM contract (and also that the terms of the original O & M contract were honoured by Conergy) involved extensive repair work and saved our client from tens of thousands of pounds in repair costs later on.

Installation inspection – Shopping centre


NWT Energy were asked to perform an assessment of a 250 kilowatt-peak solar PV system installed in March 2016 by another contractor. We initially provided a high-level report, addressing concerns already raised in a “Risk Improvement” report.

The works were not up to the promised standard, with considerable expenditure required to bring the installation up to scratch.


The modules were mounted on frames designed to be separated from the roof surface by EDPM rubber mats, in order to keep metal components raised from the actual roof fabric and to avoid damaging it.

In several areas these mats have either been placed incorrectly or have moved since installation, which has caused damage to areas of asphalt. The ballast method also presented issues and appeared haphazard.

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‘Hard’ shading

Aside from the build up of dirt on the module surfaces, several areas of the installation were subject to substantial ‘hard’ shading from fixed objects such as railings and vents.  Even one shaded module has the potential to reduce the output of an entire string of PV modules, substantially reducing the system output.

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During the evaluation we documented the frankly bizarre inverter selection that had been installed, involving four separate manufacturers of varying quality. We can only assume that this was due to supply issues, since it did not make sense from a design, maintenance or warranty perspective.

2016-12-01 12.28.49 copyFollowing the report, NWT were contracted to move the installation and site it more appropriately, at the same time as performing repairs to the roof fabric and undertaking a full electrical testing and inspection service.


The system now performs better than it ever used to and as a result NWT have an ongoing operation and maintenance contract with the owner.