University of Waterloo
Faculty of Engineering
Department of Electrical and Computer Engineering
 
 
 
 
 
Canadian Solar Solutions Inc.
545 Speedvale Ave, Guelph, ON N1K 1E6
 
 
 
 
Prepared by
Yuxin Lin
ID:20600113
userID: y276lin
2A Electrical Engineering
1 September 2017
 
 
 
 
 
Unit 258, 130-2 Columbia St
Waterloo, Ontario, Canada,
N2L 3V2
September 1, 2017
Vincent Gaudet, chair
Electrical and Computer Engineering
University of Waterloo
Waterloo, Ontario
N2L 3G1
 
Dear Sir:
This report, titled “Analysis of solar thermo-photovoltaic device testing”, was prepared for my 2A work report. I wrote this report during my work as a research and development engineering in Canadian Solar Solutions Inc. The report aims to fulfill the requirements of the WKRPT 200 course.
The aim of this report is to analyze the testing results of various solar thermo-photovoltaic modules that I tested during my work term in Canadian Solar Solutions Inc. I would conclude the problems that exist in these modules and discuss the solutions to improve these modules. At last, a new design of the solar thermo-photovoltaic system was given, which aims to improve the efficiency of the system.
The business of Canadian Solar Solutions Incorporation which is under Canadian Solar, involves in manufacturing and installing solar thermo-photovoltaic modules or systems and providing solar energy solutions for various applications all over the world. The products of Canadian Solar Solutions Inc. range from solar thermo-photovoltaic devices and systems such as solar cells, solar modules, solar power systems to off grid solar power application solutions such as performance testing on the electrical and mechanical properties of the various modules. Canadian Solar Solutions Inc. also provides some other technical support and services such as safety testing, location testing, and material level testing, which has now become an important tool for a lot of companies in the similar area.  In Canadian Solar Solutions Inc., I worked as a research and development engineer. I tested and evaluated various solar thermo-photovoltaic modules from different companies. Based on this analysis, I tried to develop a new designed of the window for the solar thermo-photovoltaic system.
I would like to thank Mr. David He for his help in understanding the properties of the solar thermo-photovoltaic system and starting my research work in this company. I would also like to thank Mr. Wangxu in helping me understand the basic design concepts of solar panel.  I hereby confirm that I have received no further help other than what has mentioned above in writing this report. I also confirm this report has not been previously submitted for academic credit at this or any other academic institution.
Sincerely,
Yuxin Lin,
ID: 20600113
 
 
 
 
 
 
 
 
 
 
 
 
 

Contribution

The Canadian Solar Solutions Incorporation is newly founded and is not a big company. The research and development engineering team only consists of 5 members including myself and all others are full-time employees.
The goal of the research and development team is to test and evaluate the quality of the existing solar thermo-photovoltaic modules and develop better solutions for the fabrication and design of new solar thermo-photovoltaic modules. The testing of various solar thermo-photovoltaic modules involves the power produced by the thermo-photovoltaic modules, and efficiency of the energy conversion in these systems, the efficiency of the circuit design, and the characteristics of the materials used in solar thermo-photovoltaic modules etc. The results of the test would be used as references for the promoting strategies of solar thermo-photovoltaic modules in the targeted companies as well as for improving the properties of the solar thermo-photovoltaic modules fabricated in the Canadian Solar Solutions Incorporation.
My tasks in research and development engineering team of the Canadian Solar Solutions Incorporation includes three major aspects. At first, after learning the characteristics of the thermo-photovoltaic system and some basic concept of designing the thermo-photovoltaic modules, I tried to design some solar panels based on the requirements of customers or other companies. This includes exploring the existing designing principles of designing solar panel and applying them into the new design. Usually, based on the requirements of customers, we know what power is needed for the solar panel and then calculate what voltage is required and how many thermo-photovoltaic cells are needed for the solar panel. We then use BlueSol to design the layout of the solar thermo-photovoltaic system and use Phtocoltaic to simulate the designed layout. After we find the simulation result can meet the requirements of the customers, we then send the design the fabricating group for fabrication. Second, I tested and analyzed the solar thermo-photovoltaic modules of various applications and concluded the problems that exist in some solar thermo-photovoltaic modules. In addition, some recommendations were also given to improving these modules. The results are significant for the promoting strategies of solar thermo-photovoltaic modules design and fabrication, which can serve as important references for the Canadian Solar Solutions Incorporation and other related companies.
The report is closed related to my job as this report contains all the work that I had to do during my work term in the Canadian Solar Solutions Incorporation. I set up the testing and analyzing methodologies and the testing contents of the solar thermo-photovoltaic modules. I optimized a testing process and finished a testing protocols for all the solar thermo-photovoltaic modules, which can thoroughly analyze and evaluate the characteristics and performance of the solar thermo-photovoltaic modules. My technical skills and research capacity were improved during designing the new solar thermo-photovoltaic modules which required a lot of research on learning many theories and design principles related to solar thermo-photovoltaic modules. In addition, my working skills such as communication and analyzing were significantly improved after this work as sometimes I need to cooperate with other team members and effective communication becomes very important in team work. Furthermore, my academic capabilities such as data evaluation are also improved. At last, compiling and writing this report also help me organize my logic flow and thoughts, which can be very important for my future career. Presenting data and results in an effective way is another important experience I learned during writing this report as I needed to make important points clear and concise.
In the broader scheme of things, the results presented in this report would serve as important references for the promoting strategies of solar thermo-photovoltaic modules in related companies as well as for improving the properties of the solar thermo-photovoltaic modules fabricated in the Canadian Solar Solutions Incorporation. The testing protocols I summarized during my work term can save a lot of time for other employee who intends to test other solar thermo-photovoltaic modules. Moreover, the testing results and the conclusions in this report can also be used for evaluation other similar solar thermo-photovoltaic modules. At last, this report contains analyzing problems in some existing modules, which can be used as reference for other researchers when trying to design new solar thermo-photovoltaic modules.
 
 
 
 
 
 

Summary

The main purpose of this report is to analyze to discuss the testing results of five different solar thermo-photovoltaic modules from different applications and develop better solutions for the fabrication and design of new solar thermo-photovoltaic modules. Several new flexible modules of different output power are also designed discussed. The content includes solar thermo-photovoltaic module testing process and method, solar thermo-photovoltaic device characteristics analysis, and solar thermo-photovoltaic panel design. Therefore, this report is for readers who have some basic knowledge of electrical engineering and semiconductor materials.
The major points in this report are arranged as below. The first chapter introduces the background and solar panels and solar thermo-photovoltaic device, which provides basic information for readers to understand the body of this report. The second chapter introduces the scope and the outline of this report. This explains the arrangement of content and the relation of different sections in the report. The third chapter contains the testing methodology and testing contents, as well as the detailed setup and material used when testing the solar thermo-photovoltaic modules. The fourth chapter discusses the testing results of five different solar thermo-photovoltaic modules from various applications and concludes the performance of these modules. The fifth chapter focuses on the new design of the solar thermo-photovoltaic modules. At last, conclusions are summarized based on the testing results and the recommendations are given for improving the performance of solar thermo-photovoltaic modules and solar panel.
The major conclusion of this report is that the machine status is very important for the performance of the STPV cell as it can lead to crack or broken panel. In addition, various recipes and mechanical adjustments should be done to improve ribbon pull test results, which means stringer recipe needs to be optimized.
 
 
 
 
 
 
Contents
Contribution. I
Summary. III
1      Introduction. 1
1.1       Background of solar panel 1
1.2       Introduction of solar thermo-photovoltaic device. 1
2      Description of this report 3
2.1       Project scope. 3
2.2       Report Outline. 3
3      Testing methodology and process. 3
3.1       Testing methodology. 3
3.2       Testing process and setups. 6
4      Solar thermo-photovoltaic device testing results and conclusions. 7
4.1       6K-5BB model 7
4.2       6K-MS model 10
4.3       6U-5BB model 13
5      New design for solar thermos-photovoltaic panel 14
6      Conclusion. 16
7      Recommendation. 17
8      Reference. 18
9      Appendix. 20
9.1       Material used in testing the 6K-MS model 20
9.2       Ribbon Pull Test 20
9.3       Model 6U-5BB Poly. 22
 
 
 
List of Figures
Figure 1 Schematic of a solar panel [2]. 1
Figure 2 Schematic of the STPV system which collects solar energy to generate heat and converts into electricity [6]. 2
Figure 3  Cross sectional view of STPV device. 2
Figure 4 Camera field of view. 5
Figure 5 An image of the solar panel string displayed on the monitor 5
Figure 6 The measurement of power distribution. 6
Figure 7 Testing results of cell loss and the percentage of each factor in the 6K-5BB model. 8
Figure 8 Testing results of NPC defects and the percentage of each factor in the 6K-5BB model. 8
Figure 9 Statistics of reasons for non-A class solar panels of the 6K-5BB model. 9
Figure 10 Distribution of maximum power value of all the 1070 solar panels of the 6K-5BB model. 9
Figure 11 Testing results of NPC defects on (A) MO# CB1706015 and (B) MO# CA1706018 of the 6K-MS model. 11
Figure 12 Maximum power Distribution of (A) MO# CB1706015 and (B) MO# CA1706018 of the 6K-MS model. 12
Figure 13 Statistics of reasons for non-A class solar panels of the 6U-5BB Poly model. 13
Figure 14 Designed STPV module producing a voltage of 6V. 14
Figure 15 Designed STPV module producing a voltage of 7V. 15
Figure 16 Designed STPV module producing a voltage of 8V. 15
 
 
 
 
 
 
 
 
 
List of Tables
 
Table 1 Result of yield test on front end and back end. 7
Table 2 The summarized failure rate of all the tests. 10
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

1         Introduction

1.1  Background of solar panel

With the development of the society and industry, electricity becomes indispensable in our daily life and industrial manufacturing. Thus, the demand for electricity is increasing. The energy resources such as coal and natural gas used to produce electricity are non-renewable and result in environmental pollution. Most countries tried to develop alternative methods. Considering the cost, stability, and the sustainability, solar power is becoming a prevailing and important choice [1]. The solar panel is a device which can use the properties of semiconductors such as Ge, Poly Silicon to convert solar energy into electricity. The principle of solar panel is to convert photon energy into electric energy [2], as shown in Figure 1. The solar panel can be used to produce electricity in a lot of areas such as illumination and lighting, self-powered spaceship, heating, and man portable power [3]. With the development of technologies such as packaging and efficiency promotion, the life and efficiency of solar panel are increasing and the fabricating cost is reducing. This makes solar panel becomes more and more competitive [4].  In order to promote the quality and efficiency of solar panel, more research needs to be carried out in this area. Therefore, investigating solar panel and its related photovoltaic devices is very significant.
Figure 1 Schematic of a solar panel [2].

1.2  Introduction of solar thermo-photovoltaic device

Solar thermos-photovoltaic (STPV) device is a solar power device which usually contains a thermal emitter and a photovoltaic diode. STPV device can be used to convert heat from solar energy to electricity.  Like normal photovoltaics, STPV device uses a p-n junction to absorb the photons or energy and generate carriers in the semiconductor materials, resulting in a potential difference in the device. This potential difference serves as a voltage to generate electricity for other applications [5]. The different between STPV device and other traditional photovoltaic devices is that the photons are not directly from the Sun but from the thermal emitter.  This means the STPV converts solar energy into heat and then into electricity [6], as shown in Figure 2. Due to the thermal motion of chargers in semiconductor materials, the thermal emitter can emit photons spontaneously. The photovoltaic diodes can convert the photons from the thermal emitter into electricity. STPV system is simpler and can be easily integrated into portable instruments, which makes it very important in various applications. Figure 3 shows the explanatory drawing of the cross section view of the STPV system. The STPV module in sealed inside the IGU inner glass and connected to the PN junction box. The major disadvantages of STPV system are its high fabricating cost and low efficiency, which are also the major research aims of most current researchers [7]. More research work needs to be done to improve the efficiency and reduce the cost of STPV system. Therefore, researching the testing results and analyzing STPV device become important for the development of STPV device and the application of solar panel.
Figure 2 Schematic of the STPV system which collects solar energy to generate heat and converts into electricity [6].
 
Figure 3  Cross sectional view of STPV device.

2         Description of this report

2.1  Project scope

The aims of the report is to analyze the testing results of various solar thermo-photovoltaic modules from different application and provide better solutions for designing and fabricating solar thermo-photovoltaic modules. By testing and evaluate the existing solar thermo-photovoltaic modules, the performance of thess modules are summarized and some recommendations are given regarding some problems that exist in some solar thermo-photovoltaic modules. The testing of solar thermo-photovoltaic modules involves the power produced by the thermo-photovoltaic modules, and efficiency of the energy conversion in these systems, the efficiency of the circuit design, and the characteristics of the materials used in solar thermo-photovoltaic modules etc. The results of the test would be used as references for the promoting strategies of solar thermo-photovoltaic modules in the targeted companies as well as for improving the properties of the solar thermo-photovoltaic modules fabricated in the Canadian Solar Solutions Incorporation. In addition, based on the testing results and the recommendations given in this report, a new design of STPV modules was provided.

2.2  Report Outline

This report can be divided into three sections. The first section contains the testing methodology and testing contents. The second section discusses the testing results of different solar thermo-photovoltaic modules from various applications and concludes the performance of these modules. The third section focuses on the new design of the solar thermo-photovoltaic modules. At last, conclusions are summarized based on the testing results and the recommendations are given for improving the performance of solar thermo-photovoltaic modules and solar panel.
 

3         Testing methodology and process.

3.1  Testing methodology

To thoroughly investigate the properties and the performance of the STPV modules, we tested the cell loss, NPC defects, ribbon pull test, electro luminescence (EL) test, the power distribution of the solar panel, and material test in the STPV modules. The testing methods and detailed testing process are shown as follows.

  • Cell loss

Cell loss refers to the number of solar panels which cannot be used after fabrication. During the fabricating process of solar panel, there are a lot of factors can result in a failure solar panel. This includes some problems that may exist in the fabrication process such as soldering nodes and lamination different layers and some artificial factors such as some mistakes made by employees when handling the solar panel. The general reason for cell loss results from the fractures on the solar panels. The value of cell loss is collected by manual computation in sampling STPV modules (usually several hundred to several thousand).

  • NPC defect

NPC defect shows the reason and amount of the non-A class (failure) solar panel. As we know, there are a lot factors accounts for a non-A class solar panel, including unsoldered ribbon, cracked cell, chipped cell, broken module, solder splatter bussing, poor soldering, and misalignment among different layers. All these can affect the performance of the solar panel and even broke the module. The number of NPC defect is calculated by manual computation.

  • Ribbon pull test

Ribbon pull test refers to testing the tensile force that the solar panel string can sustain, which is an important parameter to evaluate the mechanical properties of solar panel string.  Solar panels are soldered and formed a string using the XN Stringer. The tension was applied to the end of the solar panel string and the ribbon pull test was carried out to test the strain of the solar panel string, which is very important for the stability of the whole solar panel setup.

  • Electro luminescence test

EL test can be carried out to check defects which are difficult to be detected by eyes. After soldering the solar panel string to the anode and cathode of the buss-bar. The solar panel can be connected to the circuit loop. When applying power to the STPV module, a special camera which is able to sense wavelengths in the near infrared and visible light range can capture an image of the STPV module, while it is difficult and even impossible for the human eye to detect the signal. The EL test was carried out using the KUKA ACRP EOL EL Tester. Figure 4 shows the field of view of the camera. The testing process includes the following steps. (1) Place the STPV module on the conveyor 430 using the robot hand in the automation line. (2) The scanner scans the barcode of the STPV module to recognize and double check which module is now being tested. (3) The robot hand moves the STPV module into the EL tester for testing after verifying the barcode. (4) Connect the STPV module to contact pins. (5) Apply voltage and current to the STPV module. (6) High-speed camera captures images of the module. (7) Discharge the panel and display the captured images. Figure 5 shows an image of the solar panel string display on the monitor. At last, operator checks the images on the TV and determine if the EL test result is acceptable.
Figure 4 Camera field of view.
Figure 5 An image of the solar panel string displayed on the monitor

  • Power distribution

Testing the power distribution of the STPV module is to measure the variation of the power that the STPV module can supply. As we know, the output of the STPV module can change at the beginning when it is exposed to light and decrease to the certain point [8] [9]. The variation of power distribution is shown in Figure 6. We used the PASAN Flasher to shine the STPV module and test the power distribution of the module under different illumination intensity. The STPV module can be exposed to the light at an angle ranging from 5 to 65 degrees. We adopted 25 degrees as the shining angle which is the sun shining angle at 1:30 pm in the Ontario area.
Figure 6 The measurement of power distribution.

3.2  Testing process and setups

I developed an optimized testing protocol for various STPV modules after being familiar with the performance of the modules and the testing setups. The protocol aims to get enough data to thoroughly analyze the performance of various modules and also reduce the time and effort needed to carry out the test.  The detailed testing process is as follows.

  • Apreliminary test was carried out by operators to check the obvious cell loss on the solar panel. There might be some obvious problems existing on the solar panels such as fractures and misalignment. These problems can be easily detected by workers and failure solar panel can be removed before sending to the next step for testing.
  • The solar panels were placed on the XN stringer and soldered together to form a string.
  • Ribbon pull test was carried out to test the strain on the contact pins of the solar panel. This step can examine the soldering status of nodes on the solar panel.
  • Connect the solar panel string to the anode and cathode of the buss-bar.
  • After applying power to the STPV module, carry out the EL test on the solar panel.
  • Place the solar panels on the automatic laminator for layout laminating.
  • Use the robots to frame the peripheral of the solar panel, which is also called robotic framing.
  • Carry out power distribution test to check the performance of the solar panel.
  • Carry out the electric leakage test to examine the insulating performance of the adopted material.

By following the steps mentioned above and performing all these test, we can obtain enough data to thoroughly analyze the performance of various modules and also reduce the time and effort needed to carry out the test. This protocol has been verified by a larger amount of testing, which shows that this is an effective protocol in analyzing the performance of various solar panel modules.

4         Solar thermo-photovoltaic device testing results and conclusions

4.1          6K-5BB model

The product model of 6K-5BB (6K-Dark Blue cell 5BB Motech poly) from Motech Taiwan is tested thoroughly using the testing protocol mentioned previously. The trial quantity is 1070 pieces. The module used for testing is MO# CB1705009. The efficiency of the cell is 18.6% and the thickness of it is 200 µm. The glass adopted in the module is tempered glass with a dimension of 1954*986*3.2 mm.
We tested the yield on both the front end and the back end of the 6K-5BB model and the results are summarized in Table 1. We examined 1070 on the front end and 1040 on the back end respectively. The results show that the failure rate of the 6K-5BB model on the front end and the back end is 95.05 % and 99.33 %, respectively. This verified a good yield rate of the tested 6K-5BB model.
Table 1 Result of yield test on front end and back end.
For the cell loss which results from machine operation or artificial factor, we tried to test these factors and calculate the percentage of them. There are many factors that can result in cell loss, which means some crack in STPV cells. These factors include cracked by machines during the machine running period, crack by handling during loading into the magazine. Figure 7 shows the results of the cell loss testing and the percentage of each factor that results in cell loss. The blue histogram refers to the percentage of each factor and the yellow line depicts the accumulating percentage of all factors. From Figure 7, we can see that the crack by machine status SB#2 accounts for the highest percentage, which means most of the cell loss cases are caused by machine status SB#2. Figure 7 also shows that other machine statuses also lead to solar panel crack or broken. This means the operation of fabricating machines is influential on the quality of the solar panel.
 
Figure 7 Testing results of cell loss and the percentage of each factor in the 6K-5BB model.
The NPC defects test involves calculating the reasons that result in failure solar panel including cracked/chipped cell machine, crack/chipped cell handling, blue side unsoldered, grey side unsoldered, missing ribbon, and unsoldered busbar hard side. The testing results were illustrated in Figure 8. The cracked/ chipped cell machine and the cracked/chipped cell handling are the most common NPC defects, which accounts for roughly 53 % of all the NPC defects.
Figure 8 Testing results of NPC defects and the percentage of each factor in the 6K-5BB model.
For the non-A class solar panels, we categorized the reasons that lead to non-A class solar panels. The reasons were categorized into broken module, missing barcode, short-circuit or dead cell, micro crack, back sheet scratch cut, and bent ribbon. As shown in Figure 9, broken module (28%) accounts for the most common reason that results in non-A class solar panels. The data of all other factors such as missing barcode, short-circuit or dead cell distributed evenly at roughly 14 %.
Figure 9 Statistics of reasons for non-A class solar panels of the 6K-5BB model.
Figure 10 shows the distribution of maximum power value of all the 1070 solar panels. The vertical axis shows the quantity of solar panels for specific maximum power value, which can be referred as frequency. The horizontal axis shows the maximum power value (unit watt) that produced by each solar panel. From Figure 10, we can see that most of the solar panel in the 6K-5BB model can produce a maximum power of 275 w, which accounts for 400 in all the 1070 solar panels. From this statistic data, the average maximum power is 274.7 w and the standard deviation of all the data is 1.22, which means a deviation of 0.4% from the average value. The results show good homogeneity of all the solar panels.
Figure 10 Distribution of maximum power value of all the 1070 solar panels of the 6K-5BB model.
The results of all the tests were summarized Table 2, which calculates the total quantity, failure quantity, and the failure rate of each test. We can see that operations in the stringer have the highest failure rate (11.96 %) and EL test shows a failure rate of 4.95%. These data can be used for developing promotion protocol in the next step fabricating process.
Table 2 The summarized failure rate of all the tests.
The results show that the failure rate of the 6K-5BB model on the front end and the back end is 95.05 % and 99.33 %, respectively. This verified a good yield rate of the tested 6K-5BB model. In addition, most of the cell loss cases such as solar panel crack or broken are caused by machine status especially the SB#2. This means the operation of fabricating machines is influential on the quality of the solar panel. Furthermore, the cracked/chipped cell machine and the cracked/chipped cell handling are the most common NPC defects, which accounts for roughly 53 % of all the NPC defects. Broken module (28 %) accounts for the most common reason that results in non-A class solar panels. At last, the operations in the stringer have the highest failure rate (11.96 %). The overall cell cracked rate is higher than the current target, 90% caused by the machine, 10 % caused by handling. Therefore, the auto-palletizer needs to be modified for vertical packaging.

4.2      6K-MS model

For the 6K-MS model, we tested two modules: MO# CB1706015 and MO# CB1706018. The quantity of both modules is 107005 and 12137, respectively. The test focuses on comparing the pulling tests and power distribution of the MO# CB1706015 and MO# CB1706018. The cell efficiency of the MO# CB1706015 is 20.8% – 21.1% and the cell efficiency of the MO# CB1706018 is 20.8% – 20.9%.
We first examined scratch cracks and micro cracks in each module, we found that no defect was discovered in the MO# CB1706018 while 10 % of the 240 solar panels failed in the MO# CB1706015 testing.
The NPC defects testing of the MO# CB1706015 and MO# CB1706018 are shown in Figure 11. The vertical axis shows the quantity of solar panels with a specific NPC defect, which is referred as a percentage. The results show that cracked/chipped cell machine is the most common NPC defect in the MO# CB1706015 and EL-cracked/chipped cell handling is the most common NPC defect in the MO# CB1706018.
Figure 11 Testing results of NPC defects on (A) MO# CB1706015 and (B) MO# CA1706018 of the 6K-MS model.
 
Figure 12 shows the maximum power distribution of (A) MO# CB1706015 and (B) MO# CA1706018. The vertical axis shows the quantity of solar panels for specific maximum power value, which can be referred as frequency. The horizontal axis shows the maximum power value (unit watt) that produced by each solar panel. In the MO# CB1706015, most of the solar panel (622 out of 1773 pieces) in the 6K-MS model can produce a maximum power of 298 w with an average maximum power of 297.7 w. In the MO# CA1706018, most of the solar panel (28 out of 59 pieces) in the 6K-MS model can produce a maximum power of 297 w with an average maximum power of 296.5 w.
Figure 12 Maximum power Distribution of (A) MO# CB1706015 and (B) MO# CA1706018 of the 6K-MS model.
 
The Ribbon pull testing by XN stringer was carried out on both module and the detailed data were shown in Appendix. The results show that the strain on the head is low and does not meet the requirement of 1.8 N for the 5BB.
For the MO# CB1706015: (1) there is the occurrence of scratch in the cells. (2) Ribbon pull testing on the gray side is low and does not pass 1.8N requirement for 5BB. (3) This cell is at high risk. The cell needs to be improved and stringer recipe optimized.
For the MO# CA1706018: (1) These cells have an extremely high occurrence of scratch, micro cracks, and cracks at the front-end, which were primarily detected at EL1. (2) Cells have extremely low to zero back side ribbon pull test results. Repeatability is very poor for back-side soldering. Another possible reason provided by the head office: the aluminum board is much thicker than the silver paste. Various recipes and mechanical adjustments have been done to try to improve ribbon pull test results. (3) Some of the scratches encountered in the front-end became worse after lamination. (4) Based on the thermal mapping: XN Stringer has uneven heat distribution: within each soldering head, and between soldering heads. There appears to be a thermal difference between soldering Poly cells and PERC cells. There is more cross talk in the Poly cells than the PERC cells among different soldering heads. This cell is at high risk. It needs to be improved before being produced vastly.

4.3  6U-5BB model

We tested the 6U-5BB Poly model (6U – Dark Blue/Blue cell SF Poly cells) to explore the new adopted insulation strip in the model. The insulation strip is the BEC-201 Hangzhou First PV Material and we tested 2994 pieces. The module we tested is MO# CB1705012 and the efficiency of the cells is expected to be above 18.3 %. The insulation strip has a dimension of 100-1200 mm Width, 300 m Length, and 0.145 mm thickness. The detailed information of the insulation strip is shown in Appendix.
For the non-A class solar panels in all the samples, we categorized the reasons that lead to non-A class solar panels. The reasons were categorized into a unsoldered ribbon, micro crack, chipped cell, broken module, solder splatter bussing, and poor soldering. As shown in Figure 13, unsoldered ribbon (46 %) accounts for the most common reason that results in non-A class solar panels in the 6U-5BB Poly model.
 
Figure 13 Statistics of reasons for non-A class solar panels of the 6U-5BB Poly model.
Most of the non-A class cells are results from the unsoldered ribbon. No evidence effect on the quality of the solar panels was found in the 6U-5BB Poly model with the new insulating strip. This means no issues encountered using the new insulation strip.

5       New design for solar thermos-photovoltaic panel

With the increasing demand for electricity and the decreasing storage of non-renewable resource, solar power and the related technologies have gained more and more attention. STPV has become an important approach in these areas. While the energy converting efficiency and some other properties such as power distribution, stability, and micro crack still pose a challenge to the develop STPV industry. Therefore, an efficient and optimized STPV system design needs to be developed for the related STPV system fabricating companies.
The existing solar panel design in the Canadian Solar Solutions Inc. uses 12 pieces of cells with a width of 26 mm, as shown in Figure 14. Each six cells were connected in series to form a string and two strings were connected to the anode and cathode, respectively. Under certain weather condition with good sunshine, the system can produce a voltage of 6 V, a current of 1.33 A, and a power of 8 W. However, in cloudy weather, such system cannot guarantee to output a voltage above 5 V, which means this module is not capable of charging a cell phone. Therefore, I tried to develop a new STPV panel design to overcome this challenge.
Figure 14 Designed STPV module producing a voltage of 6V.
Based on the properties of the STPV device and the limitation of the area in the solar panel, I designed a new STPV panel by adjusting the dimensions and the pitch size among different cells. As shown in Figure 15, I used 14 pieces of cells with a width of 26 mm. Each seven cells were connected in series to form a string and two strings were connected to the anode and cathode, respectively. This system is expected to produce a voltage of 7 V, a current of 1.33 A, and a power of 9 W. Figure 16 shows another design for the STPV module, which used 16 pieces of cells with a width of 22 mm. Each eight cells were connected in series to form a string and two strings were connected to the anode and cathode, respectively. This module is expected to produce a voltage of 8 V, a current of 1.25 A, and a power of 10 W.
Figure 15 Designed STPV module producing a voltage of 7V.
Figure 16 Designed STPV module producing a voltage of 8V.
This new design can output a higher voltage compared with the existing STPV module under the same weather condition. The design aims to charge cell phones effectively even under cloudy weather.
 

6       Conclusion

With the increasing demand on electricity and the decreasing storage of non-renewable resource, solar power and the related technologies have gained more and more attention. STPV has become an important approach in these areas. This report analyzed and discussed the testing results of five different solar thermo-photovoltaic modules from different applications and try to develop better solutions for the fabrication and design of new solar thermo-photovoltaic modules. Several new flexible modules of different output power are also designed discussed. To sum up, the thesis included the following points:
The 6K-5BB model has a good yield rate and most of the cell loss cases such as solar panel crack or broken are caused by machine status especially the SB#2. This means the operation of fabricating machines is influential on the quality of the solar panel. Furthermore, the cracked/chipped cell machine and the cracked/chipped cell handling are the most common NPC defects. Broken module is the most common reason that results in non-A class solar panels. In the power distribution test, the 6K-5BB model shows a good homogeneity of all the solar panels.
In the 6K-MS model, the MO# CB1706015 test shows that the cell has panel scratch and poor mechanical stability. This cell is at high risk. The cell needs to be improved and stringer recipe needs to be optimized. The MO# CA1706018 shows that the cells have an extremely high occurrence of scratch, micro cracks, and cracks. Repeatability is very poor for back-side soldering. Various recipes and mechanical adjustments have been done to try to improve ribbon pull test results. Based on the thermal mapping: XN Stringer has uneven heat distribution: within each soldering head, and between soldering heads. There appears to be a thermal difference between soldering Poly cells and PERC cells. There is more cross talk in the Poly cells than the PERC cells among different soldering heads. This cell is at high risk. It needs to be improved before being produced vastly.
In the 6U-5BB model, most of the non-A class cells are results from the unsoldered ribbon. No evidence effect on the quality of the solar panels was found in the 6U-5BB Poly model with the new insulating strip.
The layout of the STPV solar panel can be optimized to reduce the size and the output of the system. The new design can output a higher voltage compared with the existing STPV module under the same weather condition. The design aims to charge cell phones effectively even under cloudy weather.

7       Recommendation

Based on the measurement and the analysis on different modules of STPV, several recommendations can be summarized.
At first, machine status should be carefully checked before processing the devices as the machine status which can lead to crack or broken panel is very important for the performance of the STPV cell.
Secondly, the auto-palletizer needs to be modified for vertical packaging, which can improve the mechanical stability of the STPV.
Thirdly, various recipes and mechanical adjustments should be done to improve ribbon pull test results, which means stringer recipe needs to be optimized.
Fourthly, for the 6K-MS model, the cell has high risk and needs to be improved prior production use.
 
 
 
 
 
 
 
 
 
 
 

8       Reference

[1] Archer, M. D., & Green, M. A. (Eds.). (2014). Clean electricity from photovoltaics (Vol. 4). World Scientific.
https://books.google.ca/books?hl=zh-CN&lr=&id=ztu3CgAAQBAJ&oi=fnd&pg=PR7&dq=solar+energy+++electricity+&ots=dE6w0l67zZ&sig=o1asMakqPGHl_EVAH7aSYGR_R9I#v=onepage&q=solar%20energy%20%20%20electricity&f=false
[2] How To Construct A Simple Solar Cell? Basic Operating Principle Of Photovoltaic Cell. [online]. http://www.electricaltechnology.org/2015/06/how-to-make-a-solar-cell-photovoltaic-cell.html
[3] Debije, M. (2015). Renewable energy: Better luminescent solar panels in prospect. Nature, 519(7543), 298-299.
http://www.nature.com/nature/journal/v519/n7543/full/519298a.html?foxtrotcallback=true
[4] Lewis, N. S. (2016). Research opportunities to advance solar energy utilization. Science, 351(6271), aad1920.
http://science.sciencemag.org/content/351/6271/aad1920.short
[5] Nam, Y., Lenert, A., Yeng, Y. X., Bermel, P., Soljačić, M., & Wang, E. N. (2013, June). Solar thermophotovoltaic energy conversion systems with tantalum photonic crystal absorbers and emitters. In Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII), 2013 Transducers & Eurosensors XXVII: The 17th International Conference on (pp. 1372-1375). IEEE.
http://ieeexplore.ieee.org/abstract/document/6627033/
[6] Chou, J. B., Yeng, Y. X., Lee, Y. E., Lenert, A., Rinnerbauer, V., Celanovic, I., … & Kim, S. G. (2014). Enabling ideal selective solar absorption with 2D metallic dielectric photonic crystals. Advanced Materials, 26(47), 8041-8045.
http://onlinelibrary.wiley.com/doi/10.1002/adma.201403302/full
[7] Basu, S., Chen, Y. B., & Zhang, Z. M. (2007). Microscale radiation in thermophotovoltaic devices—a review. International Journal of Energy Research, 31(6‐7), 689-716.
http://onlinelibrary.wiley.com/doi/10.1002/er.1286/full
[8] Michael, J. J., Iniyan, S., & Goic, R. (2015). Flat plate solar photovoltaic–thermal (PV/T) systems: a reference guide. Renewable and Sustainable Energy Reviews51, 62-88.
http://www.sciencedirect.com/science/article/pii/S1364032115005924
[9] Coutts, T. J., & Fitzgerald, M. C. (1998). Thermophotovoltaics. Scientific American279(3), 90-95.
http://www.jstor.org/stable/26057947?seq=1#page_scan_tab_contents
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

9       Appendix

9.1  Material used in testing the 6K-MS model

 

9.2  Ribbon Pull Test

 

  • MO# CB1706015
  1 2 3 4 5 Min Max Mean
Front 2.2 1.8 2 2.2 2 1.8 2.2 2.04
Back 1.4 1.6 1.6 1.8 2 1.4 2 1.68

 

  • MO# CA1706018
BXN1-A 1 2 3 4 5 Min Max Mean
Front 1.8 2 2.2 2.4 2.2 1.8 2.4 2.12
Back 0 0 0 1.8 0 0 1.8 0.36
BXN1-B 1 2 3 4 5 Min Max Mean
Front 2 2.2 2.4 1.8 2 1.8 2.4 2.08
Back 0 1.4 0 2.4 1.4 0 2.4 1.04
BXN2-A 1 2 3 4 5 Min Max Mean
Front 1.8 2.4 2 1.8 1.8 1.8 2.4 1.96
Back 1.6 1.4 1.8 0 0 0 1.8 0.96
 
BXN2-B 1 2 3 4 5 Min Max Mean
Front 2 2.2 2.4 1.8 1.8 1.8 2.4 2.04
Back 0 0 0 1.8 0 0 1.8 0.36
BXN3-A 1 2 3 4 5 Min Max Mean
Front 1.8 1.8 2.2 2 2 1.8 2.2 1.96
Back 0 0 0 0 0 0 0 0
BXN3-B 1 2 3 4 5 Min Max Mean
Front 1.8 1.8 2 1.8 2 1.8 2 1.88
Back 1.4 1.6 2.2 1.6 1.4 1.4 2.2 1.64
BXN4-A 1 2 3 4 5 Min Max Mean
Front 2 1.8 1.8 2 2 1.8 2 1.92
Back 1.6 2 1.6 0 2 0 2 1.44
BXN4-B 1 2 3 4 5 Min Max Mean
Front 1.8 1.8 1.8 2 2 1.8 2 1.88
Back 2.8 2.8 2.4 2.6 2.2 2.2 2.8 2.56

 

9.3  Model 6U-5BB Poly

  1. Detailed information of the insulation strip in the cells.