Effect of Shading on Half-Cut Solar Panels Power Output

ABSTRACT


INTRODUCTION
The need for electrical energy for human consumption continues to increase along with the increase in human population and increasingly modern human lifestyles is also one of the causes of increased energy consumption [1].The utilization of electrical energy sources such as coal, fuel oil, natural gas is facing greater obstacles.The obstacle is that the source is decreasing and more importantly the emergence of environmental pollution issues that endanger the life of mankind [2].However, the increase in demand for electrical energy is inversely proportional to the energy needed to convert into electrical energy, where the use of electrical energy still comes from non-renewable energy sources, namely fossil energy and can be depleted over time, and requires a very long time for fossil energy to be available and can be reused [3].
Based on this, renewable energy sources can be an alternative to continue to meet electrical energy needs.The potential of renewable energy such as solar energy, water energy, wind energy, biomass, ocean wave power, and others.Indonesia as a tropical country has advantages in sunlight.One of the utilizations of sunlight using into electrical energy using Solar Panels [4].
Solar Power Plant is an alternative generator that is free, minimal waste, does not affect the earth's temperature globally, and is not affected by fuel increases [5].Solar panels consist of an array of solar cells.In general, solar cells are made of silicon material which has properties as an excellent absorber of solar radiation energy [6].Solar power plants utilize sunlight to produce DC electricity, which can be converted into AC electricity if needed.Therefore, even though the weather is cloudy, as long as there is still light, the PLTS can still generate electricity.PLTS is basically a power supply, and can be designed to supply small to large electricity needs, either independently, or hybrid (combined with other energy sources), either by desetralization method (one house one generator) or by centralization method (electricity is distributed by cable network) [7].
The output power produced by a photovoltaic module and its lifetime depend on many aspects.Some of these factors include: type of PV material, intensity of solar radiation received, cell temperature, parasitic resistance, clouds and other shadow effects, inverter efficiency, dust, module orientation, weather conditions, geographical location and cable thickness and others [8].There are several environmental parameters that can TELECTRICAL Effect of Shading on Half-Cut Solar Panels Power Output (Bayu Angga Pratama) 74 affect the performance of solar cells including temperature changes, solar radiation intensity, partial coverage of the solar cell surface [9].Partial closure of the surface of solar cells is usually caused by dust that sticks to solar panels for a certain period of time or can also be caused by animal feces such as birds that accidentally hit and cover the surface of solar panels.Because it causes the closure of solar cells, the performance of solar cells will not be maximized, so it can greatly affect the decrease in the output power value and also the current produced.However, the extent of the effect is not yet known.

LITERATURE REVIEW
There are several similar research journals that have existed before which are the material for preparing this research proposal.Research conducted by Andhika Giyantara, Rifqi Bagja Rizqullah, and Wisyahyadi from the Kalimantan Institute of Technology entitled "The Effect of Partial Shading on Output Power on Solar Panels".The research was conducted to find out how the influence of partial shading on solar panels and the power output of solar panels.Determination of the effect of partial shading is done by doing computational simulations and also taking data directly [10].
The research entitled "Study of the Effect of Shading on Photovoltaic Polycrystalline Type" was researched by Sunsang Dody Purwanto.Research on the effect of shading on solar panels that have polycrystalline types on off-grid solar power systems.The research was conducted at the ITPLN campus, Jakarta.Effect shading that occurs in research occurs naturally due to the movement of the sun so that its rays are exposed to trees and buildings before reaching the surface of the solar panel so that a shadow effect occurs.The tilt position of the panel, which also affects the output power of the solar panel, is 35°.Parameters and variables related to this solar panel research such as Irradiation, Voltage, Current, Temperature, Ambient Temperature and Humidity.Research data collection was carried out starting at 08.00 WIB in the morning until 16.00 WIB in the afternoon for one day and every 10 minutes data collection was carried out.From the results of manual calculations, the power obtained is 57.12Watt peak and with this much power it means that the solar panel is working optimally.Then when experimental calculations are carried out to obtain real data on output power, there is a decrease in the power obtained.The largest power obtained from experimental calculations is only 23.2629 Watt and for the smallest is only 11.2818 Watt.So for the smallest power after calculating the percentage of the shadow effect, it turns out that the value is 77.44%, causing a power decrease of 11.9811 Watt.The greater the value of the shadow effect, the smaller the power produced by a solar panel [11].
The research entitled "Effect of Temperature, Angle and Shadow on Hybrid Solar Power Plant System" was researched by Shahru Neeza Ryffa Rizq.The results of this final project research are the maximum power of solar panels to a 90 ° angle factor of 126.1 watts, the maximum power of solar panels to a temperature factor of 126 watts at 55 ℃, then the maximum power of solar panels to a shadow factor of 69.2 watts.The power produced by solar panels will be very optimal if it gets enough light, is not covered by shadows and the angle of solar panels [12].
The research entitled "Investigation of Partial Shading Effects on Solar Cell Output Power" was researched by Bandiyah Sri Aprillia, Muhammad Rafiqy Zulfahmi, and Achmad Rizal.This research aims to investigate the effects of solar radiation variability due to partial shading on the output power of 1 Wp solar cells.Based on the observation results at 10:00 -14:00, the open voltage and short circuit current of the solar cell decreased as the partial shading intensity increased.The greater the partial shadow on the solar cell, the lower the output power produced.The effect of half partial shading of the total solar cell area resulted in a power decrease of 88.2%.A quarter of the shadow resulted in a 75.6% decrease in the output power of the solar cell compared to the power under normal conditions.In addition, the increase in solar cell temperature results in a significant decrease in open voltage [13].

Photovoltaic Effect
The photovoltaic effect is defined as a phenomenon of the emergence of electrical voltage due to the contact of two electrodes connected to a solid or liquid system when exposed under light energy.The difference in energy levels of light photons is what will determine the wavelength of the light spectrum.When photons hit the surface of a P.V cell, the photons can be refracted, absorbed, or passed through the P.V cell.The photons absorbed by the P.V cell will trigger the generation of electrical energy.P.V cell is a device that converts solar radiation energy into electrical energy.Basically, the mechanism of light energy conversion occurs due to the transfer of free electrons in an atom.Electron conductivity or electron transfer capability of a material lies in the number of valence electrons of a material.Solar cells generally use semiconductor materials as free electron producers [14].

Semiconductors
Semiconductors are materials that have a level of conductivity between insulators and conductors [15].The main parameter that divides semiconductors from other materials is the band gap energy.Band gap energy refers to the energy difference between the top of the valance band and the bottom of the conduction band which determines the amount of transition energy used to make an electron jump from the valance band to the conduction band [16].This band gap varies in size for each semiconductor material but is required not to exceed 3 or 4 eV (3 x 1.602 x 10-19, or 4 x 1.602 x 10-19 J) which is the lower limit of the material called an electrical insulator [17].

RESEARCH METHODOLOGY
The research method used in this study uses an experimental research method, a research method used to find the effect of certain treatments on others in controlled conditions that are predictive, namely predicting the consequences of a manipulation on its related variables.

Specifications of Solar Panel Used
The solar panels used in this study are 470 WP half-cut solar panels of 2 pieces installed in series.The solar panels used are JinKO solar panels.

Research Variables
In this study, the variable is the artificial shadow effect.Cardboard will be placed with rectangular patterns and circular patterns.Where these patterns will be placed on solar panels with the percentage according to what will be studied.

Rectangle Pattern
On the rectangle of the pattern, a shadow will be created and placed on the corner of the solar panel.Starting from a percentage of 10% with an increase in percentage every 10% until the shadow percentage reaches 100%.Where the data needed is only the amount of voltage and the amount of current generated by the solar panel.Here are some illustrations for rectangular pattern shadow effects The above is an illustration of the shadow effect placed in a rectangular pattern where the shadow will be placed at the corner of the solar panel.The blue panel is the panel that is not shadowed and the black panel is the panel that is shadowed.

Circle Pattern
In this circular pattern, the shadow will be placed in the center of the solar panel with a circular shape.Starting from a percentage of 10% with an increase in percentage every 10% until the shadow percentage reaches 100%.Here are some example images for the circle pattern shadow effect.Above is an illustration of the shadow effect placed in a circular pattern where the shadow will be placed in the center of the solar panel.The blue panel is the panel that is not affected by the shadow and the black panel is the panel that is affected by the shadow.

Data Collection Process
To make it easier during data collection in this study, solar panels are designed in such a way as to facilitate data collection.The following is the existing PV installation of the research to be carried out.In this study, the solar panels used are 2 pieces where the panels will be arranged in series.The solar panels are connected to the busbar then connected to the MCB and inverter, in the inverter the DC voltage from TELECTRICAL Effect of Shading on Half-Cut Solar Panels Power Output (Bayu Angga Pratama) 77 the solar panels is converted to AC voltage and then stored in the battery which will be used to serve the load.For the installation of the data logger will be stored between the bus bar and inverter.

Result Analysis
With the data as parameters, the results will be obtained in the form of a comparison value of the current and voltage of the shadow effect with a square pattern, circular pattern, and random pattern with a percentage of 10% with an increase in percentage every 10% until the percentage of shadow reaches 100%.As well as its effect on the output power value of the half-cut solar panel.

Research Flowchart
In conducting research, a research framework is used to make it easier during research.The research began by collecting journals related to research.The test is carried out by applying a shadow with certain dimensions (area) to the surface of the solar panel.Shadows are made from cardboard which is shaped according to rectangular and circular patterns.The solar pane one by one with dimensions of 10%, 20% to 100% of the total surface of the solar panel.The sun moves every hour so material is placed on the surface of the solar panel where the material is considered a shadow.The material is not placed on the surface of the panel at a certain distance so that the shape of the shadow used does not change.
The data to be obtained is the solar panel voltage in open circuit (Voc) and working voltage of the solar panels is closed circuit conditions VPV, IPV working current.There are similar solar panels installed in series to produce 2 times the Voc voltage and working voltage of each panel.Measurements were carried out throughout the day starting from 08.00 to 18.00 with varying weather at that time.Each shade (% shade) applied to the solar panel lasts for one hour.After obtaining the desired data, analysis is then carried out and measurements are taken so that conclusions can be drawn, the research is complete.

RESULTS AND ANALYSIS
Analyzing and describing the data obtained by conducting research for 14 days using a data logger where the logger functions to monitor the results of the influence of the shadow effect on half-cut solar panels.The output is recorded into the SD card, after which the data obtained will be processed again using Microsoft Excel software to facilitate the creation of graphs of voltage, current, and power on half-cut solar panels in 14 days.

Voc Voltage Without Shadow
To get the voltage Voc from half-cut solar panels (PV) arranged in series, the PV terminal cable is not connected to the inverter, or called an open circuit.

Voc Voltage with Rectangular Shadow
The Voc voltage when 10% shadow is applied to the PV surface has an average value of 103.69 V, this Voc value is almost close to the Voc value on the PV data sheet which is 2 times 52.14V or 104.28 V.Although strings 1 and 2 of the lower left PV are shadowed (the lower 1 string is not shadowed), the voltage appearing on the left PV is the sum of the series of the upper 3 strings, which means the Voc of a PV.This happens because Voc is an open voltage, no current is output by the PV, so the voltage at the PV terminals is the highest voltage of the circuit, no current branching applies and the bypass diode works.The measurement value of 68.03V is close to the calculated value of 67.12 V, there is a difference that can be caused by the accuracy of the measuring device used in the study.This is the same analysis for 30% to 100% shading.
The graph of the relationship between Voc and the application of shadow is shown in Figure 9.It can be seen that the larger the shadow, the smaller the Voc voltage.When the shadow is applied at 70%, the remaining Voc comes from the right PV consisting of string 3 (bottom) and string 6 (top) or only 1/3 of the right PV Voc.When the shadow is applied at 80%, the Voc is already 0V because the shadow has covered the left PV and right PV.

VPV Voltage and Working Current of Rectangular Pattern IPV
To obtain the VPV and IPV voltages, the solar panel is made in a closed circuit, which is connected to the load.The load used is a spotlight with a power of 200W that works at a voltage of 220 VAC.The working voltage of the load is sourced from an inverter-controller capable of producing 1000W of power.The PV is connected to the inverter-controller, then the inverter-controller is connected to the battery and also to the load.The inverter is connected to the battery to store electrical energy, but is connected to the load to distribute electrical energy.It is important that the electrical load is applied so that the energy storage unit is not full.If it is full, the charging current to the battery becomes 0A or IPV=0A which is regulated by the invertercontroller.The shadow pattern applied is rectangular, when the shadow is applied from 10% to 70% there are strings that work to emit electric current, but when the shadow starts from 80% to 100%, the entire string is covered so that the current is not current issued by PV because the working voltage is 0V.
To obtain working voltage data, the voltage sensor is connected to 2 PV output wires (+ and -) while the IPV working current is obtained by connecting the ACS758 sensor in series to the + wire from the PV.The data logger will store the working voltage and current data every 3 seconds.In the graphs below, it can be seen that the greater the percentage of shading applied, the working voltage of the VPV decreases, as well as the current released by the PV.At 70% shading, the PV voltage is around 12.10 V with a charging current of 0A.This is because the PV voltage is smaller than the battery voltage which is around 24 V, which causes no battery charging current.For shadows of 80% to 100%, the PV voltage is zero due to all strings from the left and right PVs being covered.

Voc Voltage Application of Circle Pattern Shading
As with the square pattern shading, obtaining the Voc voltage from the circular pattern is to apply the shading to the PV and then the terminal ends of the PV are connected to the data logger.
The following are the results obtained from measuring Voc with a circular pattern.The Voc voltage weakens as the percentage of shadow applied gets larger, even when 30% shadow is applied, the Voc voltage is 35.64 V.The Voc value is already insignificant for battery charging.

Working Voltage and IPV Working Current Shadow Circle Pattern
The working voltage and current measurement circuit for the circular pattern shading application is like that of the rectangular pattern, only the pattern changes.The 10% circular pattern shadow as shown in Figure 13 covers PV1 (left PV) but does not cover PV2 (right).The covered strings on PV1 are strings 1, 2 and 3 so that the voltage across each of those strings is 0. However, the top is not covered by the shadow.The top is half of a half-cut PV that outputs half of its maximum current, which is ½ of 10.86 A equals 5.43 A. Since PV2 is not shadowed, its working voltage is 43.28 V with a current of (supposedly) 10.86 A.
There are 2 maximum power from this, namely PV working at higher voltage but lower current which is called global maximum power and PV working at higher current but lower voltage which is called local maximum.When the PV works with global maximum, the current released by PV1 is 5.43 A with the overall voltage being the sum of the maximum voltages of PV1 and PV2, which is 86.56: Global Maximum -10% shadow: PV voltage  10g =  1 +  2  10 = 43,28 + 43,28 = 86,56 Work flow:  10 = The data logger records the PV working at the global maximum when there is a shadow of 10% as shown in Figure 12.When 30% shadow is applied, the current released by PV is very small, around 1 A, while 40% and 50% shadow, the current released by PV is no longer there because the PV voltage is smaller than the battery voltage.The relationship graphs of PV voltage, current and power are shown in Figure 14 and Figure 15.It can be seen that the voltage drops drastically after 30% shading is applied, so the current and power follow the curve of PV voltage.

CONCLUSION
From the test results with the application of rectangular and circular pattern shadows on half-cut solar panels arranged in series of 2 pieces the application of rectangular pattern shading has differences with the circular pattern, namely: in the rectangular pattern: a significant voltage drop occurs when the shadow is applied at 60%, the PV can still output current although it is relatively small, the PV no longer releases voltage when the shadow is more than 70%, while in the circular pattern: the PV voltage starts to drop after the shadow is applied at 30%, if the shadow is more than 30% then the PV no longer flows.The data logger records the PV work when shading occurs at maximum global power, because the inverter-controller used is able to track and distinguish maximum global power and minimum global power.Half-cut solar panels are able to work

Figure 1 .
Figure 1.Solar Panel PlacementThe following are the specifications of the solar panel:

Figure 4 .
Figure 4. Diagram of Current and Voltage Measurement on PV with Data Logger

Figure 6 .
Figure 6.Application of Rectangular Pattern Shading for Voc DataThe measuring device, the data logger, has been set up to measure the Voc voltage.The data logger works to get the Voc value and stores the measurement results every 3 seconds.Changes in the magnitude of the shadow made every hour will be stored directly on the SD card.

Figure 7 .
Figure 7. Voltage Graph of Voc from 08.00-18.00hours The graph of the relationship between Voc and time in Figure 7 shows that in 1 day of measurement from 08.00 to 18.00 the Voc voltage around 104 V lasted until the 9th hour or 17.30 and in the last ½ hour Voc had weakened (decreased) at 96.15V.The Voc voltage values obtained from the measurements are close to the Voc values listed in the PV specifications issued by the manufacturer (vendor).

Figure 8 .
Figure 8. Illustration of Applying 10% and 20% Shading The Voc voltage when 20% shadow is applied to the PV surface has an average value of 68.03 V.When viewed from Figure 8, specifically the left PV, strings 1 and 2 at the bottom and strings 4 and 5 at the top are exposed to the shadow, which are not exposed to the shadow are strings 3 (bottom) and 6 (top).Thus 2 bypass diodes work resulting in a voltage drop of 2x0.6=1.2V.Strings that are not exposed to shadows are worth 1/3 of the Voc voltage which is 17.38 V so that the total Voc voltage of the two PVs is:  20 = 1 3   − 2  +  ℎ

Figure 9 .
Figure 9. Graph of Voc Relations with Rectangular Shadow Placement

Figure 11 .
Figure 11.PPV relation to rectangular shadows4.3Results of Circle Pattern Application 4.3.1 Voc Voltage Application of Circle Pattern ShadingAs with the square pattern shading, obtaining the Voc voltage from the circular pattern is to apply the shading to the PV and then the terminal ends of the PV are connected to the data logger.The following are the results obtained from measuring Voc with a circular pattern.

Figure 12 .
Figure 12.Graph of Voc against Shadow Change

Figure 14 .Figure 15 .
Figure 14.Relation of VPV (Left) and IPV (Right) to the Shadow of the Circle

Table 1 .
Specifications of Solar Panel

Table 2 .
Voltage Voc Without Shadow