Zero Energy

Solar Knowledge: Photovoltaic System

According to UNEP report, it is alarming to learn that about 2 billion people in the world, most of them living in the rural remote areas of developing countries have no access to electricity and further 2 billion are severely under-supplied. This imbalance in energy distribution is one of the most important causes of social unrest. Other factors of concern to environmentalist, scientists and to a certain extent to government as well includes growing need of energy demand with increasing global population, excessive use of fast depleting existing traditional energy resources to meet these demand and its impact on global climate changes.

Progress has been made in rural electrification by extending main grid line to rural and remote areas of Nepal. But geographical and climatic conditions in combination with low population density, minimal energy demand and low growth potential in most of the remote part of the country makes the rural electrification costs often too expensive. And it has become clear that with mere traditional electrification methods such as grid connection to these isolated remote areas will not be reached within foreseeable future. With the increasing rate of migration and urbanization, government is forced to focus on improving and extending the urban electrification system which is still inadequate with daily load shedding of 16 hours in dry season.

Because of very high initial investment required for building large power plants , its long gestation time, high cost involved in developing transmission lines, security issues and strict environmental regulations, larger power plants have become uneconomical in many regions.

These problems can be solved significantly by the use of renewable energy resources like Photovoltaic technology. With the advent of new technologies, advances made in electronics and energy storage devices have provided new opportunities for generating electricity. Photovoltaic Technology is a proven and easy use of solar energy to generate electricity. Electricity can be generated in load center, with minimal transmission cost and loses, to supply electricity in remote communities, utility peak load shaving, telecommunication towers, water pumping or communities and irrigation, municipal park lighting and many other usages.

High cost associated with solar photovoltaic(PV) system has been one of the major hinderance to the technology's market penetration. Proponent of this technology argue that typical analysis overlook many of the benefits of solar PV and fails to capture its enhanced value that results from temporal and locational characteristics. On site power generation is one of the major advantage that is often overlooked in cost analyses. Power from central station generation required significant investment in transmission and distribution infrastructure specially in case of Nepal where load centers are scattered in transmission-constrained remote areas. These investments can be reduced significantly if more power were generated on load site.

Thus, a valuation of solar PV electricity production that compares it to the average cost of generating electricity, ignoring the potential savings in transmission and distribution infrastructure, will tend to under-value the power from PV. Thus, high cost plant located in a transmission constrained area can make economic sense when compared to the cost and feasibility of transporting power to that location.

The developed system focuses on devising a system that automates the SHS design based upon minimal input parameters. System targets non-technical people as its main audience. The system shall also provide thorough breakdown into choosing set of components to determine overall system load, provide a choice of local components for the load profile, and thus calculate the overall system through a connectivity diagram to help users visualize how their system would be. Moreover, the design would be backed up with an elaborate financial analysis including the breakdown of total project cost, the rate of return, and the payback period. This is targeted at helping the user to understand his/her investment in the SHS thus designed, and how they will receive returns off their investment. This will in fact motivate the users to invest in SHS.

The main aspect in design of stand-alone solar home system is the reliable power supply required by the consumers. Therefore it is essential to select the appropriate number of solar panels, batteries and charge controller of correct rating to compromise between the system reliability and cost.