Grid-connected photovoltaic system in Malaysia: A review on voltage issues

Photovoltaic (PV) systems are the most promising renewable energy source in Malaysia due to its abundant solar irradiation. The Malaysian government has launched various renewable energy programs to encourage the use of PV systems. Most of the PV systems are single-phase and the installation is customer driven. Therefore, the growth of PV system in low voltage (LV) distribution network has the potential to raise several technical issues including voltage rise and voltage unbalance. Furthermore, Malaysia is a warm country and geographically surrounded by the sea. The vaporization of the sea water together with the seasonal winds results in a large amount of passing clouds, making this country to be, possibly, the cloudiest region in the world. The solar irradiation is therefore highly scattered and fluctuating. The power output from PV is highly intermittent, hence producing an enormous amount of voltage fluctuations and flickers on the LV distribution networks. All these voltage issues have to be studied experimentally and addressed thoroughly at the early stage before the amount of PV on the network becomes substantial. Therefore, a 7.2 kW grid connected PV system on a radial LV distribution network has been set up to study the voltage issues at the point of common coupling. The power outputs of the PV system are characterised and compared with that of other countries. The probability density of voltage rise and voltage unbalanced factors are derived from the measurement data. Short-term and long-term voltage flicker indexes are calculated to evaluate the severity of the flicker emission. These results are valuable to the policy makers, electricity regulatory body, utility company, customers and PV manufacturers because they can change the policy on the renewable energy and the regulatory framework.