[ Spotlight: Test equipment ]
Solar PV installations are a
growing area of business for electrical contractors
Calibration In order to ensure optimal performance and product longevity, calibration is vitally important. While some companies always ensure their equipment is calibrated, some simply ignore it, thereby shortening the life of the instrument. Tony Kumeta, general manager UK and export at Ideal
Industries, explains: ‘The majority of manufacturers specify regular maintenance and recalibration at least every 12 months. Calibration is important to ensure the accuracy of test equipment and should be part of any contractor’s quality procedure. It is highly advisable to make sure this is done, especially when working in applications where the inaccuracy of a non-calibrated piece of test equipment could jeopardise safety.’ Manufacturers also recommend that electrical contractors
self-check their instruments between periods of full calibration. However, it is important to use a check box with full EN 61557 test capability, otherwise all the test parameters required by BS 7671 may not be verifi ed. For example, a continuity tester should operate at >200mA short circuit current and an insulation tester at 500V.
Maintenance issues Solar PV is not a ‘fi t and forget’ technology, which is why periodic verifi cation and testing of the system should be carried out, as electrical faults or wiring failures can cause a serious ineffi ciency in the ability of the panel to produce power. Di-Log Solar’s Dave Sweetman, explains: ‘Effective electrical
testing is vital in proving the safe installation of a new system. However, it is also important to verify ongoing functional performance. There are two main areas of maintenance required on a solar PV system – cleaning of the PV panels and a yearly check of the system/inverter. These can both be combined with periodic inspection and testing.’
48 ECA Today November 2011
Interpreting test results correctly is a major factor in getting an installation right, as failure to do so can have serious consequences
Looking ahead Microgeneration technologies such as solar PV are giving the electrical contracting industry a much needed boost and offering a way for electrical contractors to add revenue streams to their existing activities. Correct inspection and testing ensures a top quality installation and ensures that a customer’s outlay yields a healthy return on investment.
March of progress
Defi ned as the direct conversion of light energy into electrical energy, it is generally agreed that the discovery of the ‘photovoltaic effect’ is down to French physicist, Edmond Becquerel, in 1839. He made a cell out of two brass plates immersed in a liquid and, when exposed to sunlight, this unusual contraption produced an electrical current. It wasn’t until 1953–1954 that the photovoltaic
About the author
Rob Shepherd Rob Shepherd is a freelance journalist, and regular contributor to ECA Today, who has worked in the electrical contracting industry for more than 10 years.
effect was fi rst used for solar panel energy conversion, with the main emphasis in space applications, where one of its main uses was to power satellites. Eventually, household and industrial applications developed at the end of the 1960s and the beginning of the 1970s. In the middle of the 1970s, photovoltaic
electrical energy was still very expensive. However, a considerable – and continuing – drop in costs of photovoltaic electrical energy has been observed since 1975, leading to a considerable growth of the photovoltaic systems industry during the years since.
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