National Physical Laboratory

Solar panel power quality

As unprecedented levels of photovoltaic (PV) solar panel systems are being connected to the electricity supply system, the actual effect on the system has been little understood.

Solar panels
Image courtesy of iStockphoto

Network operators are responsible for ensuring that clusters of PV solar panels can be accommodated without detrimental effects to the energy supply power quality. They need to understand the impact on voltage and power quality prior to investing in large scale installations within their systems and, if necessary, make provisions for network reinforcements to mitigate any effects on power quality or reliability.

During a recent measurement survey on a photovoltaic cluster in the UK, monitoring of power quality revealed no critical degradation during periods of PV generation. However, a rise in voltage of between 1 and 4 V, directly associated with PV generation, was observed, bringing the voltage level on this network close to statutory limits.

Such detailed measurement has enabled network operators planning to add substantial PV systems to their cluster to consider the scale of installation and the impact of that installation on the security of their supply.

Of additional interest is the observation from these measurements that, on average, PV units operate at half capacity on the sunniest days. From data provided, due consideration must be given to the cost-benefit and CO2 savings estimates in order to justify investment.

More on NPL's work on Electrical Measurement

For more information, please contact Paul Wright

Last Updated: 26 Mar 2012
Created: 22 Mar 2012

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