The experts at Test Instrument Solutions (TIS) shine a light on test equipment for solar PV installations while taking a look at the different types of units available and what they do.
There are various pieces of instrumentation available for testing solar PV installations, so this article will attempt to clarify what is required and when.
Irradiance meter with clampmeter
This is a really easy way to establish whether a solar PV system is behaving as it should under the prevailing sunlight conditions. A good Irradiance meter will give the expected power generated by the sun in a reading of Watts per square metre. When utilised with an appropriate clampmeter, the user can measure the voltage and current outputs from the array to give the power output and therefore confirm that the expected power correlates with the actual value measured.
Solar PV commissioning instrument
This is usually required to be used when installing grid connected PV systems and/or the requirement for MCS compliance. The Code of Practice for grid connected solar PV systems (second edition) lists the following minimum test requirements derived from EN 62446:
• Continuity of earthing and/or equipotential bonding conductors,
• Polarity test,
•Combiner box test,
• String open circuit voltage test,
• String short circuit current test,
• Functional tests,
• Insulation resistance test.
For small to medium installations, DC side MFTs are available with insulation and open circuit voltage tests of up to 1,000 V and short circuit current tests up to 15 A. For these types of applications, TIS offers the PVCHECKs.
For larger commercial and industrial installations there is now a requirement for insulation and open circuit voltage tests of up to 1,500 V, along with short circuit current tests of 40 A. The newly launched PVCHECKS PRO will carry out all of the requirements under the standards along with being able to test at 1,500 V and measure short circuit currents of 40 A.
Maintenance of solar PV systems
This is, of course, vital to ensure the long term return on investment of the installation. One factor which can affect the performance of an array is if a panel has developed an insulation fault down to earth or has been wired incorrectly initially.
If such a fault is detected, one way to find the defective component would be to disconnect each panel in turn to determine the offending unit, which is rather time-consuming to say the least. However, both PVCHECKS PRO and PVISOTEST have a game changing feature called ‘GFL’ – Ground Fault Locator. This setting on both units allows the user to pinpoint a faulty panel in a string of up to 35 with just one connection and key press.
Of course all of the above is in addition to the requirements on the AC side of the installation covered by BS EN 7671 – but that’s a story for another day!
Browse the full range of TIS PV testing equipment online here
