Impact of Small Decentralized PV Grid-connected Plants on Load Shedding in Nepal

Chianese, Domenico and Rivola, Davide and Shrestha, Jagan Nath and Zahnd, Alex (2013) Impact of Small Decentralized PV Grid-connected Plants on Load Shedding in Nepal. In: 28th European PV Solar Energy Conference, Paris, France. (In Press)

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Abstract

The current unreliability of the electrical network in Nepal, and the growing needs of users, together with the high level of losses in the electricity distribution grid can be partially resolved by means of a decentralized and partly autonomous electricity supply. The Nepali grid is characterized by weak stability, frequent accidental powercuts and regular planned load shedding schemes (up to 20 hrs. a day in the dry season), causing particular suffering to SMEs (Small and Medium Enterprises). A feasibility study [1] has demonstrated the cost advantages of a small solar PV grid connected system in combination with a battery back-up, compared to traditional petrol gensets or battery chargers from the grid with stand-alone inverters. The pilot project foresaw the design, construction and monitoring of 5 grid-connected 1.11 kWp PV plants at three different strategic locations, P1, P2 and P3, in the urban and semi-urban environment of the Kathmandu valley. While four of the PV systems are standard grid connected systems, of which three are installed in “No-Load Shedding Zone” P2 and one in “Load Shedding Zone” P1, the fifth system P3, is installed in a “Load-Shedding Zone”, but is designed with a battery bank backup system, and can therefore function as a micro-grid. The setup parameter limit of the grid-connected inverter was adjusted in accordance with the effective situation of the distribution grid (voltage and frequency limits, duration of power cut, etc.). Performance monitoring of the plants started in late 2012. The first 9 months of analysis shows energy generation losses of about 47.6% (475kWh) at P1, due to the load shedding schedule at the time. The performance of the three PV plants at P2, where no load shedding occurs, was as expected, with all generated energy fed into the grid. The 1.11 kWp PV grid-connected plant with a battery backup at P3 in effect performs as a stand-alone system providing enough energy for one household and an NGO office.

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