Economic Analysis of Hybrid Power Plant (Solar-Diesel) on Kawaluso Island, North Sulawesi

— Kawaluso Island is one of the outermost islands in Indonesia with a distance of 68 KM from the city of Tahuna or 5-10 hours by boat from the capital of the Sangihe Islands Regency, Tahuna. Currently, electricity on Kawaluso Island is supplied by a diesel power plant (PLTD) with a capacity of 200 kW. This condition causes Kawaluso Island to be electrified 12 hours per day. So that additional sources of power plant are needed so that the electricity on Kawaluso Island is on 24 hours a day. Therefore, a solar power plant (PLTS) is one of alternative as additional power for Kawaluso Island and reduces the cost of production. A diesel power plant where the price of industrial fuel reaches up to Rp. 24.500 and it make Cost of Energy Rp. 10.360/kWh. The method used in this study uses the Levelized Cost of Energy (LcoE) method. The results of the analysis show that the hybrid between diesel power plant and solar power plant 64 kWp and 72 kWp has a Life Cycle Cost (LCC) value of Rp24.389.601.114,40 and Rp. 20.589.498.278,40 With a Cost of Energy (COE) of Rp. 7.432 and Rp. 5.601/kWh. Net Present Value (NPV) obtained is positive. And the payback period is 3 and 9 years of investment and is categorized as feasible to continue.


I. INTRODUCTION
Indonesia has a many islands with challenges of electricity. As we know all the big system electricity in big islands of Indonesia like a java bali or sumatera its already providen. But in the other cases like in the small island, they just reliable with diesel energy. Although currently renewable energy in Indonesia is starting growing up.Reliable with diesel energy can up the cost of generation and it doesn't provitable or it will make a pollution in the environment. Kawaluso island is one of the outhermost islands in northern Sulawesi Electricty in Kawaluso island depends from Diesel energy and it has 12 hour operation. with a distance of 68 KM from the city of Tahuna With the cost of generation up to Rp. 10.360/kWh, its important to find the alternative energy to make lower cost of generation than diesel generator. Currently, the electricity condition on Kawaluso Island consists of a 160 meter Medium Voltage Network, a 1,368 meter Low Voltage Network and one sub station. Currently, Kawaluso Island has a diesel power plant with a capacity of 2 of 100 kW and operates 12 hours per day. Based on the operating data of the diesel power plant, the daily electricity consumption on the island of Kawaluso around 170 kWh to 200 kWh. The current engines are used for daily electricity is Deutz F6L-912 engine and the Deutz F10L-413F engine in standby condition. Specific fuel consumption (SFC) condition of the F6L engine is 0.42 and the F10L engine is 0.91.

A. Hybrid Power Plant
Hybrid Power Plant is a power plant consisting of 2 or more generators with different energy sources. For example, such as a Solar Power Plant combined with a Diesel Power Plant. One of its functions is either if the sky is overcast and the sun disappears during the day, the power plant will be supplied by a diesel generator otherwise when diesel is off then the power plant will be driven by solar panels [1] or the cost of generation in a area can be reduced if one of the diesel power plant has higher cost of energy. Indonesia is located on the equator, so Indonesia has abundant sources of solar energy with Jurnal EECCIS Vol. 17 an average solar radiation intensity of around 4.8 kWh/m2 per day throughout Indonesia [2]. In planning a solar power plant, there are several components that must be prepared in the project. The main components included solar modules, batteries, and inverters. a) Solar Modules Solar panel is a device that converts sunlight energy into electrical energy by means of a photovoltaic effect, therefore it is also called a photovoltaic cell (Photovoltaic cell -abbreviated as PV). Solar panels consist of many solar cells or solar cells. Solar Cell is an active element that converts sunlight into electrical energy. Solar cells generally have a minimum thickness of 0.3 mm, which is made of slices of semiconductor material with positive and negative poles. The basic principle of making solar cells is to utilize the photovoltaic effect, which is an effect that can directly convert sunlight into electrical energy [3]. b) Battery Batteries are tools that are used to store electrical energy so that we can use it at any time. Battery (battery) is an energy storage device that is charged by the flow of Direct Current (DC) from solar panels. Besides storing DC energy, the battery also functions to convert chemical energy into electricity [4]. c) Inverter An inverter is an electrical device used to convert direct current (DC) into alternating current (AC). Inverters convert DC from devices such as batteries, solar panels / solar cells into AC. The use of an inverter from a solar power plant (PLTS) is for devices that use Alternating Current (AC). The output voltage can be fixed or variable with a fixed or variable frequency. The variable output voltage can be determined by changing the Direct Current (DC) input output voltage, in which case the gain of the inverter is kept constant [5].

B. Economic Analysis
An analysis to determine the feasibility of an activity to be carried out based on the parameters of total yield, productivity, and economic benefits as a whole is called economic analysis. Economic analysis is necessary to obtain information on the technical, technological and financial aspects of project [11].Economic analysis is calculated based on financial feasibility parameters that consider the ability of an investment to return the funds used. In financial economic analysis there are several calculation criteria that can be used, including LCOE NPV (Net Present Value), IRR (Internal Rate of Return) and Payback period.

a) Levelized cost of energy (LCOE)
Levelized cost of energy (LCOE) represents Life Cycle Cost (LCC) or the total value of investment, operational & maintenance costs, equipment replacement costs, a generating facility based on the present value in one financial cycle and work cycle, then this value is converted in annual installments with adding the calculation of the inflation rate. The biggest energy cost for solar energy lies in the initial investment costs, while O&M costs relative small. This is in contrast to the energy costs of diesel generators where the initial investment costs tend to be small but the O&M costs are large (especially fuel costs) [8].

b) Net Present Value
The Net Present Value (NPV) method is a method that is carried out by comparing the present value of net cash inflows (proceeds) with the present value of outlays. Therefore, to calculate the feasibility of an investment using the NPV method, data on initial cash outflows, future net cash inflows, and the desired minimum rate of return (M. Giatman, 2017). NPV is commonly used to calculate the return on an investment. So that you know whether the value of the investment has a profit or loss [6].
a) Payback Period The Payback Period (PP) method is a method used to calculate the length of the period required to return the money invested from the annual cash inflows (proceeds) generated by the investment project (M. Giatman, 2017). If the proceeds are the same each year, the Payback Period (PP) of an investment can be calculated by dividing the total investment (outlays) by the annual proceeds [6].

III. RESEARCH METHODOLOGY
Methodology uses to determine the capacity of a solar power plant and determine whether a power plant has advantages or disadvantages. The first is determine the load profile of Kawaluso Island, designing a solar power plant and the second is economic analysis.

A. Load Profile of Kawaluso Island
Currently, the electricity condition on Kawaluso Island consists of a 160-meter Medium Voltage Network, a 1,368-meter Low Voltage Network and one sub station. Currently, Kawaluso Island has a diesel power plant with a capacity of 2 x 100 kW and operates 12 hours per day. The following chart is the Load Profile of Kawaluso Island.

B. Designing of Solar Power Plamt
To design a solar power plant, there are 3 criteria that must be met. Determine the irradiance value, determine the capacity of the solar power plant and calculate the investment capital.

Capacity of Solar Power Plant
To determine the capacity of the solar power plant, it must know the load requirement of the power plant. To reduce the intermittent effect of output solar power plant, design of solar power plant has an output 15-20 kWh. The rest will be helped by Diesel power plant. After the load requirement is already know, we need to calculated the capacity of the power plant and the total of solar modules. Power generated when the temperature t℃ = 0,35% °× temperature rise(°) Power Generated After temperature rise = ℎ °= − ℎ ° From the calculation of the maximum output power of the solar panels when the temperature rises to tºC, the value of the Temperature Correction Factor (TCF) is calculated using the following formula = ℎ 28,6° After the calculation TCF, next is PV Area are used for this Solar power plant. The optimal time that can be used for the photovoltaic process is 5 hours. After calculation capacity of solar power plant, next is determine the number of solar panels Number of panels = To find out the capacity of the inverter to be used, we will calculate the series-parallel of the solar modules used. The determination of this circuit is carried out to determine the amount of power released by the solar panel as a whole, if to increase the current it is installed in parallel, and if you want to increase the voltage it needs to be arranged in series.
Minimum of series circuit =

Economic Analysis
Calculation of the initial investment cost of PLTS is based on the cost of the components. The initial investment cost for PLTS consists of the cost of PV modules, structures, inverters, installation costs, shipping costs and initial operations. In calculating the initial investment cost of PLTS, it is assumed that US$ 1 is equal to Rp. 15,323 (Oktober 2022) To know how much cost of energy that we need. First one is we must know the cost operation and maintenance. Operation and Maintenance of solar energy will influence by data of National Renewable Energy cost (NREL). And the diesel will influence by fuel cost and operation cost. After that we need to know about life cycle cost Levelized cost of energy presenting as life cycle cost or total cost from investment capital, operation and maintenance,and cost of equipment change. And then this cost will calculated with interest rate (discount factor and inflation rate). Cost of energy (CoE) is the cost required to generate or produce every 1 kWh of electrical energy. The cost of energy is obtained from the quotient between the annual costs the total energy supplied per year. Cost of energy (CoE) determines a project will be implemented or not.
To arranged the cost of operation and maintenance of solar energy and diesel energy will calculated by: Annual PV O&M is Present value of operation and maintenance as the lifetime. (i) is intereset , (d) is discount factor and (n) is the year of the project power plant.
Levelized cost of energy presenting as life cycle cost or total cost from investment capital, operation and maintenance,and cost of equipment change. And then this cost will calculated with interest rate (discount factor and inflation rate)[]. The Life Cycle Cost value will be calculated based on the following equation.
Life cycle cost (LCC) = C + Mpw + Rpw Cost of energy (CoE) is the cost required to generate or produce every 1 kWh of electrical energy. The cost of energy is obtained from the quotient between the annual costs the total energy supplied per year. Cost of energy (CoE) determines a project will be implemented or not. The Cost of Energy (COE) of Hybrid power plant is calculated by dividing the annual LCC (ALCC) by Production of electricity. Annual LCC (ALCC) Hybrid power plant can be calculated using the following equation.
And the cost of energy will calculated by.
Cost of Energy Hybrid Power Plant = Net present value is the cash flow that will counted after discounted by the interest rate factor. The value of Internal rate of return will be determined with the condition NPV = 0. This method using a approach of value the interest. So we need to know when the NPV is negative and the NPV is positive.
Payback period is the time required for present value is higher than investment through income from the project. After we look the table of Cash Flow then we can decide the payback period.

A. Irradiation Value and Temperature
For the solar irradiance value, the average value for the area of the kawaluso island will be used, which is 5.32 kWh/m2 obtained from data from NASA (National Aeronautics and Space Administration) or the Aeronautics and Space Agency.  The maximum output power of solar panels when the temperature rises to 29.36ºC, the following formula is used: In calculating the number of panels used, there are 2 cases that will be used, namely hybrid solar power plant covering 2/3 of the total load or 16 hours a day. And the condition of PLTD as a follower with a constant 5 kWh load.

a) Solar Power Plant with 2/3 Daily Consumption
For the first condition, it will calculate the number of panels needed with a load that covers 2/3 of the total load.

Daily load Solar power plant (2/3) = Daily Load x 2/3
Daily Load = 480 kWh x 2/3 = 320 kWh The optimal time that can be used for the photovoltaic process is 5 hours so that the amount of power that can be generated is PV Area = For the second condition, it will calculate the number of panels needed with the diesel power plant still operating for 24 hours with a limited output of 5 kWh per hour and the rest will be supplied by the solar power plant plus batteries.
Daily The optimal time that can be used in the photovoltaic process is 5 hours so that the amount of power that can be generated is: PV Area = Determines series-parallel of solar modules The determination of this series-parallel of solar modules is carried out to determine the amount of power released by the solar panel as a whole, if to increase the current it is installed in parallel, and if you want to increase the voltage it needs to be arranged in series.  Area of Array The location of the Solar power plant will be close to the diesel power plant area. After knowing the number of solar modules to be installed, it is necessary to calculate the total area that will be used for module installation.

D. Inventers
For the calculation results, the number of solar modules of 74,8 kWP used is 144 modules and the voltage is 736,38 V. Based on the data sheet from the inverter to be used, the minimum input voltage is 200 Volts to 1000 Volts. So that the required inverter is 1 inverter. The inverter used has a capacity of 75 kW so that it meets the requirements for an inverter.
For the calculation results of 84,3 kWp solar power plant, the number of solar modules used is 162 modules and the voltage is 736,38 V. Based on the data sheet from the inverter to be used, the minimum input voltage is 200 Volts to 1000 Volts. So that the required inverter is 1 inverter with a capacity of 90 kW.

E. Investment Capital
Investment capital of 74,8 kWp Solar power plant

F. Operation and Maintenance Cost
The following is the cost of operation and maintenance of 74, 8  year is assumed to be the same price as the current inverter price. The present value of costs that will be incurred to replace the inverter in years 5, 10, 15 and 20 can be calculated using the following equation:  The cost of replacing the 74,8 kWp and 84,3 kWp Solar power plant battery for the 5th, 10th, 15th and 20th year is assumed to be the same price as the current battery price. The present value of costs to be incurred for battery replacement in years 5, 10, 15, and 20 can be calculated using the following equation: