Solar Home Systems in Nepal

With about 300 days of sunshine per year in most parts of the country, an average of eight light hours per day and being situated on the ideal 30° North “solar belt”, Nepal presents very good conditions for the use of solar power. Solar PV modules installed at an angle of 30° South can intercept a daily average of 4.8 to 6.0 (kWh/m2) of solar energy in most locations throughout the country. Reports of studies say that Nepal can generate 21,000 MW of electricity.

Photovoltaic (PV) technology is applied for electricity generation from Solar resource. Solar PV is a clean and environmentally friendly technology that means it does not require any fuels. The high reliability of operation and little need for maintenance makes it ideally suited for rural areas. PV systems have been used in Nepal to power telecommunications centres, navigational aids, in pumping systems for irrigation and drinking water, and for household electrification. Electricity from Solar PV technology to at least lighting the residence is known as Solar Home system.

The solar cell generates electricity through the photovoltaic process. Sunlight is composed of photons and as they strike the solar cell some of these photons are absorbed. The excess energy is transferred to an electron, which uses the extra energy to free itself from its normal place. Once freed, the electron is available to become part of an electric current. An electric field in the cell provides the voltage needed to drive the current through an external load. The generated electricity is stored in a battery. Thus, a PV system for domestic applications is called a solar home system (SHS).

A Solar home system consists of a PV module, a battery, a charge controller and 3-4 LED bulbs. The system provides power for lighting and operation of household appliances for several hours. Operating TV set, radio and charging mobile phone are the commonly preferred uses.

The first programme to electrify a village with Solar home systems was financed through the Solar Electric Light Fund (SELF) of USA and jointly implemented with the Nepali NGO Centre for Renewable Energy (CRE) and the Nepali manufacturer Solar Electricity Company (SEC). This programme resulted in the installation of 64 Solar Home Systems in Pulimarang village in Tanahun District in the beginning of 1994. Later, Government of Nepal through its Alternative Promotion Centre (AEPC) had distributed around 1.1 million households. 

Such systems are expected to provide lighting facility for the residences at a minimal amount. Their capacity used to be 20w, 40w, 60w, 80w, 100w or more in some conditions. As said above such systems can provide lighting facility replacing kerosene lamps. Gradually, users’ demand extended to have SHSs to be good for mobile phone charging, laptop charging, operating TV and radios. So as size of SHSs also enlarged accordingly.

At the time when the Government of Nepal is saying that 93 per cent of households now have been connected with the national grid. Within 2 more years to come, every household will have access to electricity. The statements further say that a portion of people at remote locations will not be provided with national grid facility. That means, 100,000or more households will still remain far from the national grid. The authorities repeatedly state that the households which will not connect with the national grid will be provided electricity by mini-grid systems.

The service rendered by SHSs of small capacity is not suitable for any normal households in the present context. Energy requirement of the users have been extended. They are looking for higher capacity systems or consistent distribution of quality electricity. So, SHSs needs to be redefined according functionalities of the system.

Small SHSs are still useful to provide minimum facilities to the natural disaster victims by including as one of must relief materials. Any type of natural disasters– landslide, flood, fire and earthquake etc. – the victims need a safe rescue at first. Then they look for shelter, thirdly food and medicine, after that they look for reliable lighting at the shelter and communication supports. Communication is important to warn people to evacuate or to be prepared. Moreover, communication is needed for the first action to inform rescue authorities at local levels and relatives. As mobile phone has been a reliable and must to have facility, charging of mobile phones are one of the most essential components. Thus along with must needed components, small SHS should be provided for resuming communications.

Small SHSs are also useful to those rural people who have 5 amp electricity connections available through the national grid. Studies and experiments say that 5 amp electricity connections can operate induction cooktop or similar device. But other functions needed cannot be used. If they have small SHS they will be able to use electricity from the national grid to operate kitchen equipment while operationalizing other devices powering by small SHS.

Moreover SHSs now should have an enlarged shape and strength. The SHSs needs to provide all electricity needed for the households at remote locations. That means the SHS should be able to provide electricity for cooking and other functions as well. The system will work as an equivalent to the Solar mini grid of a household size.

Such extended size SHS will be able to generate and store electricity required for cooking food in the morning, day and evening. Roughly a 2.5 kWh battery backup and suitable charger, inverter should be in the set of devices.

The users have to have metallic improved cookstove and briquettes, pellets or dried fuel wood as immediate back in cloudy day situations. Thus, SHS needs to be redefined as per the size and strength of the system as Small SHS, SHS and Extended SHS.