RIDS-Nepal (Rural Integrated Development Services – Nepal) is a non-profit Nepali NGO (Non-Governmental-Organization).
The RIDS-Nepal main head office in Imadol, Lalitpur district, is at the outskirt of the main urbanized, densely populated city area. The office’s electricity line is connected to the grid at a considerable distance away from a transformer. That results in significant voltage losses at peak user times, when the voltage drops down to 155 Volt AC. The RIDS-Nepal office experiences, like all the other private households and industrial companies, daily load shedding according to the NEA set load shedding calendar, which is revised periodically. In order to utilize and feed into the grid the maximum daily solar PV array generated energy, the 1.11 kW rated PV array system is equipped with a back-up battery bank, to store the generated energy during times the grid is not available. Further, some of the office’s local loads are also met directly with the solar PV array generated energy when the grid is not available. Thus, Plant 3 is a solar PV grid connected system which has the capability to work as well as a grid independent, or RAPS (Remote Area Power Supply), system, at times the grid is not available. It therefore provides the best solution for both conditions, feeding into the grid when the grid is available, as well as working as a RAPS system, charging a battery-bank and providing electricity to defined local user loads, when the grid is not available.
In this way, Plant 3 can maximize the generation of energy from solar whenever the sun is shining, either feeding electricity into the grid, if available, or providing electricity to charge the battery-bank and/or to some defined local user loads, if the area experiences load shedding. However, this also means that Plant 3 is a much more complex system, with intelligent energy management and defined battery bank charging and discharging processes maximizing the lead-acid battery bank’s life cycle expectancy. It allows us to learn the detailed behavior of lead–acid batteries’ daily charging and defined discharging pattern, performance, energy in/out efficiency, expected life-cycle and cost of energy with battery back-up, all important and thus far neglected fields of research in Nepal. Plant 3 provides for the present Kathmandu situation, with many years to come load shedding forecasted by NEA, the best solution, as it provides the locality where the PV system is installed with electricity 24/7, independent of the grid’s availability. Thus, while it is a fully equipped solar PV grid connected system, looking forward to the times when there will be no more load shedding in Kathmandu, when hundreds of thousand solar PV grid connected systems will be generating the daily needed energy for the city, it also provides the consumer with the important electricity around the clock now and till there is not enough energy generated nationwide to end load shedding.
By the end of February 2013, the RIDS-Nepal Plant 3 solar PV system has not yet been connected to the grid, as the process to get NEA’s permission to connect to the grid is still going on.
You can download the Plant 3 Block Diagram here.