Technical Design and Financial Feasibility Analysis of Off-Grid Photovoltaic Power Supply System for Residential Load

Abstract

Due to intensive promotion to use renewable energy, by the various benefits obtained by utilizing, and then supported by advances in generation technology: causing various parties to divert the type of fuel for their energy use activities. The same thing happens to residential electricity consumers, driven by the advantageous of electricity power generation that can be done on the consumer side, independent operation, reliability and quality of power, many consumers try to install renewable energy based generation such as photovoltaic system for their electricity supply. However, looking at the tariff of utility electricity and considering the investment needed: building a photovoltaic-based supply system is not necessarily the right choice. This paper presents a technical design for electricity supply of a residential load through an off-grid photovoltaic system. The technical basis for designing and the capacity of its constituent components is explained, as well as the analytical techniques carried out to assess the financial aspects of the development and operation of the system. The results of this analysis can be used for deciding whether it is appropriate to divert the source of electrical energy to the photovoltaic system. To show the steps of the analysis, a case study was carried out by designing an off-grid photovoltaic system for a residential load characterized by its daily load curve. The capacity and costs were calculated and financial analysis is carried out by looking at the extent to which the designed system can provide comparable benefits if the power is supplied from the utility at the prevailing price, as well as how long the system must be operated to obtain a breakeven return on investment. Based on the daily load curve in this case study, it is known the total daily energy consumption of the load is 6.885 kWh. This amount of energy must be provided from photovoltaic module with 5 hour effective per day, so the minimum capacity of PV-module is 1463.65 W. For an autonomy time of 1 day, a minimum energy storage capacity of 8.965 kWh is required. Investment costs which include the cost of procurement, system development, and the tax are Rp. 150,008,037. The financial benefits are calculated based on prices of the PLN 2016 non-subsidized tariff. It was assummed that the energy used that should be supplied from PLN, is substituted by photovoltaic generation system. NPV analysis and Payback period shows that the off-grid photovoltaic generation system will be feasible if the electricity price is 2.3 times the current price, and the discount factor (DF) for construction is 2.5%, in such electricity prices and DF factor, the payback period is reached if generation system is operated at least until the end of the 25th year. Financial analysis showed the inability of the off-grid electricity supply scheme based on the designed photovoltaic generation for current conditions.