Case: Electrification of Shenge Village
Project title: Shenge Village Gets Solar Electricity
Client: Research Institutes of New Energy Resources, China
Naps Contact: Paavo Suuronen
Completion: 1996
Objectives:
- To make the every day life easier in the isolated village
- To connect the inhabitants with the rest of the nation, increase the awareness of national affairs
- To provide reliable electricity to the community living far from areas covered with basic infrastructure
Site specific issues:
Shenge village is located four kilometres above sea level in the Tianjun County, Haixi region, in the Midwest of the Qinghai province. With the road condition improved over the years, the small town is a little more than 6 hours drive from Xi Ning, the capital city. There is no motor transport in the village, yaks being the usual means of transport. There are about 350 inhabitants in the village.
Climatic variations of the area, from bitter winters to sweltering summers, demand a truly reliable power solution. The average annual temperature is 0 degrees C; the minimum is -29 and maximum +20. Cloudy periods don’t last longer than 5 days.
Before the installation of solar electricity, the village already had been connected to the main electricity network but with some restrictions. For example, the use of the washing machine was limited to two hours in a week. The unstable hydro power plant had failed to provide electricity to county level residents resulting to vexatious power cuts and limited use of household appliances. In order to ensure the reliability in power supply, a central solar electricity system was installed in connection with the main grid.
The consumption of power has seasonal variation; in summer when the local farmers travel far with their animals the consumption is rather low.
Implementation:
The village houses are now electrified with a photovoltaic system that has an inverter converting the direct current coming from the solar modules to normal grid electricity. The solar electricity system is divided into two independent parts. Both systems have own solar array, charge controller, battery and inverter supplying the main switchboard. This makes the system easy to maintain. The controllers operate separately based on the battery state of charge and actual solar insolation. During given normal daylight conditions the solar modules supply sufficiently power to keep the system continuously functioning and the batteries fully charged. The basic principle is that solar modules shall be able to produce more electricity than the loads draw from the system.
The solar electricity system, which has a total capacity of 7000 Wp, produces power for the basic needs of the village at all times. The load equipment and daily usage based on solar electricity is as follows:
|
Device
|
Quantity
|
Power Watts/device
|
Use hours/day
|
|
|
|
|
|
|
Lights
|
140
|
20
|
4
|
|
Television
|
45
|
60
|
4
|
|
Radio
|
50
|
10
|
4
|
|
Washing machine
|
7
|
400
|
0,5
|
|
Satellite receiver
|
1
|
200
|
4
|
For safety reasons the usage of electricity is prioritised, here listed in the priority order: township government (most important), hospital, school, bank, shop, old folk homes (2), and veterinary station (less important).
The installation of solar electricity system took a week, because the equipment cabin and battery banks had been constructed earlier. The villagers themselves built a shelter for the equipment and arranged the building materials.
Equipment and technical specifications:
The equipment comprises:
- Solar array 7000 Wp (144 pieces of 50-Watt solar modules)
- Panel centres and structures for the solar modules
- Sine wave inverter type 10 INV 120/220/50
- Naps NSCi system controller, 2 pieces, both tailor-made for the project
- Valve regulated, heavy duty battery bank with capacity of 2000 Ah, sized for 10 days of autonomy
Conclusions:
Over the years, the demographic situation in Shenge village has not changed very much, though some nearby similar counties have doubled their population and the need for power as well. Shenge villagers are quite content with their life. Now some even have refrigerators and VCD in their houses, powered by sun. And in some cases they even feel a little privileged when the nearby unstable hydro power plant failed to provide electricity to county level residents. The failure is due to drying up of the river that once flowed next to the village.
Lighting plays an important role in villagers feeling of comfort and when performing daily chores. Television is an evening entertainment for many.
In overall the technical performance of the system is positive. The inverter has failed twice though; the problems were solved by welding some loose parts and by replacing the control board. Now the system is running well.
The communal service level is better now as the power consumption is prioritised. Important services are carried out without interruptions thanks to system design.
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