The impact of photovoltaic systems on distribution transformer: A case study

In this paper, the results obtained after monitoring a distribution transformer during an 18 months period are described and discussed. The transformer fed several households, each with a grid connected photovoltaic system, and it was found that the power factor at the transformer attained unusually low levels. This was due to the fact that under some conditions, the systems provided a large portion of the active power demanded by the households, while the grid supplied all the reactive and distortion powers. The operating temperature was used as an indicator of the stress on the transformer. The temperature was at its lowest when the systems were providing the maximum energy available from the solar cells.