Testing of Solar Power Plant Components Off-Grid Systems and Engineering Economic Analysis at Cemara Island, Brebes Regency,

. Indonesia is a country that is geographically located right in the equator and variously advantage and the wide for the use of solar energy. Indonesia has a relatively high radiation level, which is 4.80 kWh / m2 / day. Cemara Island is a tourist place but does not have electricity from PLN because access to its location is still difficult to reach. So from that chosen the planning system for the use of electrical energy using solar energy. However, economic analysis is needed so that the estimated weaknesses of the off-grid solar system can be estimated so as to reduce the risk of losses. The testing of each component in the Solar Power Plant system also needs to be done to determine the condition and quality of the components to be used. The economic analysis of the Cemara Island Solar Power Plant System with an initial investment of Rp 52,553,000, in scenario 1 uses interest at 6%, then in scenario 2 without using interest. Through calculations by looking for the value of COE (Energy Cost), NPC (Net Present Cost) and BEP (Break-Even Point), so that costs can be calculated by the manager with the number of 11 managers per month.


Introduction
Indonesia is a country that is geographically located right on the equator and provides a variety of advantages and great potential in terms of solar energy utilization.The energy sector is one of the most important sectors in Indonesia because it is the basis for all other developments, especially by building electricity supply infrastructure to rural areas.The use of solar energy in Indonesia has a very good prospect, given that geographically as a tropical country, across the equator it has good solar energy potential.This is because the amount of solar radiation depends on the location of latitude, atmospheric conditions, and the position of the sun on the equator.Indonesia has a relatively high radiation level which is equal to 4.80 kWh/m 2 /day.This is a big advantage for Indonesia in terms of the utilization and generation of solar energy into electricity.The Cemara Island Tourism Area, Sawojajar Village, Wanasari District in Brebes Regency is a new tourist attraction that is starting to be in great demand by domestic tourists from inside and outside Brebes Regency because of the natural beauty offered by it.Cemara Island is a small island measuring 0.12 × 5 kilometers to the north of Brebes Regency.This island offers the beauty of a charming panoramic beach with rows and cool pine trees.However, the absence of electrical energy is an obstacle for local residents to use optimal electricity services.The absence of facilities in the form of lighting installations and electrical installations has led to not optimal coastal tourism activities and the nature of the region.So with the absence of vacant land on the island that is not used, it can be optimized with the construction of the off-grid solar power system as a source of electrical energy for the residents of the island because State Electricity Company has not been able to access the location.The way solar cells work is by utilizing the theory of light as a particle as it is known that both visible and invisible light has two properties, which can be as waves and can be particles called photons, this discovery was first revealed by Einstein in 1905 [1].The use of solar panels as an alternative to generator sets and conventional electricity as electricity needs for residents who sell or live in the area.The writing of this final project aims to test the components of the off-grid PV system that has been planned and implemented as well as analyze the economy after the construction of the off-grid solar power system for residents in the Cemara Island Tourism Area.

Discussion
In this research, there are two economic analysis scenarios that used to determine the effect of interest on the value of net present cost (NPC), cost of energy (COE) and break-even point (BEP) [2].In addition, collecting data directly at the Solar Power Plant in the Cemara Island Tourism Area, Sawojajar District, Brebes Regency, Central Java Province to find out the various parameters needed to analyze each component of the Solar Power Plant.There is some indicator that will be used to determine the quality of each components solar power plant on Cemara Island.

Testing of Solar Panel System Components
In this testing phase, data is collected directly at the Solar Power Plant on Cemara Island Tourism Area, Sawojajar District, Brebes Regency, Central Java Province to find out the various parameters needed to analyze each component of the solar power plant.Some of the data needed for this test are as follows:

Calculation of input power
Due to the testing carried out in the condition that the solar panel is connected in series-parallel so that the cross-sectional area of the solar panel becomes 7.87 m2.Calculation of solar panel input power at 6.00 a.m. can be calculated based on the following equation: Pin = E x A = 28.3x 7.87 (1) = 222.82watts

Calculation of Fill Factor
From the measurement results of the solar panel circuit at 06.00 WIB, the Voc value of 13 V and Isc 0. Then the Fill Factor value is obtained by calculating according to the following equation: FF = (Vmp x Imp) / (Voc x Isc) = (11,625 x 1.0528) / (14 x 1.12) = 0.78 (4)

Maximum power calculation
The maximum power value that can be released by solar panels at 06.00 can be calculated based on the following equation: Pm = Voc x Isc x FF = 14 x 1.12 x 0.78 = 12.27 watts (5)

Calculation of efficiency
Calculation of the efficiency of the actual solar panel data can be calculated using the following equation: By using the same efficiency equation, the efficiency of the solar panel system is obtained every hour as in the following table: The table shows the efficiency value of solar panels per hour on day 1, where the highest efficiency value at 17.00 is 13.4% and the lowest is at 11.00 and 13.00 which is 4.7%.Whereas in the Table shows the efficiency of solar panels per hour on day 2, where the highest efficiency value at 09.00 is 9.5% and the lowest at 17.00 is 3.4%.There are several factors that affect the output efficiency of solar cells, namely solar radiation, solar cell temperature, orientation of solar panels, the tilt angle of solar panels, and the influence of shadows (shading factor) [4].Low-efficiency values due to external conditions such as the intensity of the sun and temperatures that are too high or too low.

Battery Test Results
Tests on the battery can determine the condition and quality of the battery to be used.To get the parameters of good condition or not the battery condition is carried out several tests, namely testing the Voltage rating, Cold Cranking Ampere, State of Charge, State of Health, and Internal Resistance Testing the battery individually is done directly before connecting to the solar panel so that the battery condition is known before the construction of the Solar Power Plant system.

Voltage Rating Analysis on the Battery
To analyze the voltage rating on the battery, it takes a comparison between the voltages obtained when testing the voltage rating on the nameplate as in the following table:

Analysis of Cold Cranking Ampere on Battery
The value of Cold Cranking Ampere (CCA) capability is obtained from 4 times the battery capacity, ie the value must be greater than 400 CCA because the battery used is 100Ah to say the condition of the battery is in good condition [5].Based on the battery test data table, all batteries are in good condition with no damage at all.Factors that affect large CCA are usually found in the durability of the battery whether the battery has long been used or is still in a new condition.In this Solar Power Plant system, the battery used is all new batteries so there is no damage when a new battery is purchased and used.

Analysis of State of Charge and State of Health on Battery
Based on the results of the battery measurement data in the table, it can be analyzed State of Charge and State of Health on the battery.Based on the table, it can be seen the condition of the SOC on battery 1, battery 2, and battery 3 under conditions of 100% indicating that the battery is fully charged and battery 4 in the condition of 94% indicates the battery is almost full.For SOH conditions, due to the condition of the new battery, all batteries have a SOH value that is still above 90% (> 90%) [6].From the table, it can be seen that the internal resistance value of all batteries is below 5.5 Ohm (<5.5 Ohm).This indicates that the condition of all batteries is in good condition.If the value of internal resistance is above 5.5 Ohm (> 5.5 Ohm), the battery will heat up faster and can damage the lifetime of the battery and will be damaged quickly [7].

Inverter Test Result
Take measurements using an oscilloscope at the inverter output to see the waveform generated from the inverter and the voltage.To compare the inverter output voltage values from the test results with the nameplate, data nameplate is needed as in the following table: The inverter used is a Pure Sine Wave type inverter where the output from the inverter must be a sine wave.To calculate the amount of voltage generated by the inverter through the results of the oscilloscope in Figure 1, the calculation is carried out as follows: Vpeak = n x V / div x probe scale (7) Where: n = number of boxes v / div = voltage per box Then the calculation is obtained, Vpeak = 3.2 x 10v x 10 = 320v Vrms = Vp / √2 = 320 / √2 = 226.27Volt Based on the results of testing the inverter and calculation, the resulting voltage is 226.27Volts.The comparison of the value of the calculated output voltage with the nameplate shows that the value in the calculation is almost in accordance with the voltage value on the nameplate.Differences in inverter output voltage values are tested by rating voltage on the nameplate due to the loss of power due to inverter losses and from converting the inverter.So it can be concluded that the inverter works well and the output voltage is a sine.

Drop Voltage Test Results
Testing for falling voltage is done by measuring the voltage at the source voltage (output of the inverter) and the voltage at the final load.From the tests that have been done, we get the voltage as in the following table:

Economic Analysis
The economic analysis carried out will be two scenarios, where the first scenario is a scenario with a source of capital originating from loan funds from the loan lending service provider, for example, a bank with an interest rate of 6%.The initial investment (C) used to build this SOLAR POWER PLANT system amounts to Rp. 52,553,000, maintenance costs (Mpw + Rpw) amounted to Rp. 5,479,196 and with a yearly burden of 687 kWh.

Scenario 1 with an interest rate of 6%
The present total net cost (NPC) is the main economic output in the SOLAR POWER PLANT system.The first year NPC value of the Cemara Island SOLAR POWER PLANT system with an interest rate of 6% can be seen in the following calculation: NPC = (((C x CRF) + Mpw + Rpw)) / CRF = Rp.52,722,053 Then the value of NPC for 25 years is Rp 122,595,514.Break even point is a condition where the value of investment and income is at point 0, or it can be said that it is in a condition not experiencing a loss and not experiencing a profit.Average annual operating and maintenance costs for a period of 25 years and an interest rate of 6% can be searched in the following ways: Then the cost to be paid by the people of Cemara Island for each shop in a month in scenario 1 is as big as: Cost per month = (electricity sales revenue) / (11 stalls x 12 months) Cost per month = (Rp.9,590,245) / 132 = Rp.72,653 So per shop is required to pay Rp. 72,653 per year

Scenario 2 without interest rates
The NPC value in scenario 2 is not affected by the value of interest rates, so the value of the NPC in the first year is only the sum of the initial investment costs and maintenance costs (Rpw), as well as the following year until the project year 25, can be seen in the following calculation:  1 -=  + Biaya O&M&R =  52,553,000 + Rp 5,479.196= Rp 58,032,196 Cost of Energy in scenario 2, has a difference with the scenario 1where in scenario 2 there is no interest rate factor that affects the value of COE.Then, the value of COE can be calculated using the following equation: By knowing the value of COE, it can be seen that the income earned within a year by doing COE multiplication with the total electrical energy used in a From these calculations, it can be seen to get a capital turnover or BEP, so the sale of power is needed at 17,175 kWh.The cost to be paid by the Cemara Island stall manager is divided equally by each stall, with annual revenue costs of Rp 2,695,587, the calculation of the cost of each stall on Cemara Island can be calculated as follows: Cost per month = (electricity sales / month) / (11 stalls x 12 months) Cost per month = (Rp.7,581,316) / 132 = Rp.57,434 Then the cost to be paid by the people of Cemara Island for each shop in a month in scenario 2 is Rp.57,434.

Table 3 .
Battery Test Data

Table 4 .
Efficiency of Solar Panels Per Hour On Day-1

Table 5 .
Efficiency of Solar Panels Per Hour On Day-2

Table 7
Battery Rating Voltage Analysis

Table 8
Battery Internal Resistance Analysis

Table 9
Inverter Specifications

Table 10 .
Drop Voltage Test Result It can be stated that the falling voltage that occurs is in accordance with the existing standards, namely at PUIL Indonesia 2011 which states that the limit of the drop voltage permitted is 4%.
To obtain the Cost of Energy (COE), Net Present Cost (NPC) and Break Even Point (BEP) values, several calculation steps are carried out.In terms of the economy, the energy costs of a Solar Power Plant differ from the energy costs for conventional plants.This is because the energy costs of a Solar Power Plant are