BILKENT UNIVERSITY

Department of Electrical Electronics Engineering 

Bilkent 06800 Ankara, Turkey

A FINAL REPORT TO OFFER ENGINEERING SOLUTIONS TOREDUCE FALL RISK WHEN CLEANING SOLAR PANELS ON

MEHMET AKİF ERSOY ANADOLU HIGH SCHOOL’S ROOF,

KIRIKKALE

Damla Yıldız

21703475

ENG401: Technical Report Writing and Presentation

Instructor:Marlene Denice Elwell

Section: 14

TABLE OF CONTENT

 

ABSTRACT

This study contains information regarding a security risk occuring while cleaning solar panels on theroofs. The main purpose of conducting this study is to offer technical solutions to clean solar panels on Mehmet Akif Ersoy Anadolu High School’s roof in a safer way. Usage of Airobotics Solar Drone or Robsys RTM Series Solar Panel Cleaning Robot and installation of LDR- Arduino Based Wiper system were offered as solutions. All three solutions’ safety reliability, applicability and cost were assessed by research methodologies which were literature review, market research and expert opinion. For assessment, each criterion was given a weighted percentage according to their significance and each solution was considered by their overall scores for each criterion. According to the study’s findings, all three solutions got the same score for safety reliability. Airobotics was found as the most expensive solution. LDR- Arduino Based Wiper System got the highest score for applicability and cost, therefore it was chosen as the optimal solution to reduce fall risk in the given pilot study area. After the system installation, damage control on the panels and placing the designed circuit into where it will not get wet were recommended.

 

1.0 INTRODUCTION

Solar energy is a widely used renewable energy source in Turkey [1]. To convert solar energy toelectrical energy, solar panels are used; therefore, the panels can be on different places such as roofs, lands and mountainlands. There is dust, bird droppings and pollen accumulation on the panels’ surface (see Appendix A). Due to this accumulation, the panels’ efficiency can reduce up to 25% in time [3](see Appendix B). Therefore, the panels need to be cleaned.

However, cleaning solar panels especially on roofs is not safe because of fall risk [2]. Solar panelson Mehmet Akif Ersoy Anadolu High School’s roof are cleaned manually too.

This study’s purpose is to propose engineering solutions to reduce fall risk when cleaning solar panels on Mehmet Akif Ersoy Anadolu High School’s roof. The study’s impact is to bring back reduced efficiency to its standard value without human injury occurring by falling. The study’s significance is to reduce possible human injury risk and recovery cost paid by Social Security Institution (SGK).

2.0  PROBLEM DEFINITION

Solar panels can be cleaned by rain however, rain cannot clean them fully [4]; therefore, the cleaning process should be done in a mechanical way. In the mechanical way, cleaning staff climb up to the school roof with cleaning materials such as brushes, wipers, cleaning water and they clean the panels by hand. While they are cleaning the panels, fall risk occurs due to the roof slope, wind and slipperiness caused by dropped cleaning water [5], [6]. A man in Adana lost his balance while cleaning solar panels on his house’s roof and fell from the roof and died [7].

There are 146 solar panels on Mehmet Akif Ersoy Anadolu High School’s roof [8] (see Appendix C).These panels are cleaned manually by cleaning staff who are responsible for the panel cleaning (see Appendix D). The roof is not flat, it has 15 degrees slope so the slope increases fall risk. The panels on Mehmet Akif Ersoy Anadolu High School are near the roof edge [10] (see Appendix E); therefore, cleaning staff bend down to clear those panels and due to the roof slope, wind and slipperiness, fallrisk increases.

2.1  Problem Scope

Fall risk from Mehmet Akif Ersoy Anadolu High School’s roof while cleaning the solar panels isspecified by the following parameters:

• Who: Cleaning staff who are responsible for panel cleaning and the schoolmanagement
• What: Fall risk when cleaning solar panels on the PSA
• When: Cleaning staff climbs up the the roof to clean solar panels
• Where: Mehmet Akif Ersoy Anadolu High School’s roof
• Why: Roof slope, slipperiness and wind
• How: Balance loss

3.0  PROPOSED SOLUTIONS

Three technical solutions which minimize the need to climb up the roof were proposed to reduce fall risk from Mehmet Akif Ersoy Anadolu High School’s roof while cleaning the solar panels.

3.1   Airobotics Solar Drone

Airobotics Solar Drone (A.S.D.) was designed in collaboration with a drone manufacturer Airobotics and a solar panel manufacturer [11] (see Figure 5 in Appendix F ). A.S.D. has 5 cm position accuracy [12]. Its cleaning system can clean any type of dirt [13]. It has a real time remote control, dual video camera and monitoring system [13]. It has a docking station where its battery and water storage are replenished autonomously [14], [15] (see Figure 6 and 7 in Appendix F). The docking station has a 30 liter water payload which can clean ~30 panels [14].

Moreover, A.S.D can cover a range of 80 km² area [14] and also panels which have 1960 mm length, 990mm height and 40mm width [16]’, working situations can be monitored by the drone’s thermalmonitoring insight [17]. If efficiency loss or part damage occurs in any panel, it can be detected by the thermal monitoring insight because the panels’ thermal color looks different than it should.

Only one A.S.D is enough to clean all the panels on Mehmet Akif Ersoy Anadolu High School’s roof; however, cleaning water storage in the docking station needs to be refilled six times to clean thepanels in one attempt. The docking station will be installed by Airobotics in the school garden.

3.2  Robsys RTM Series Solar Panel Cleaning Robot

Robsys RTM Series Solar Panel Cleaning Robot was designed for solar panel cleaning on roofs [18](see Figure 8 in Appendix G). It has a remote controller [19], so there is no need to come to the roof edge or bend over to clean the panels (see Figure 9 in Appendix G). The robot has two lithium batteries, one inside the robot one separate and the batteries have 3-4 hours battery life [20]. The robot’s approximate weight is 57 kg [21]. In addition, the robot has two plastic brushes which were designed for solar panel cleaning [21] and the robot can clean both with and without water by these brushes [22]. The robot has the capability of cleaning 25 meters in 10 minutes [21] and it can move spaces between the panels [22]. Only one robot is enough to clean all the panels on Mehmet Akif Ersoy Anadolu High School’s roof. Since it can be portable [21], no installation is required. It can be used by cleaning staff after purchasing.

3.3  LDR-Arduino Based Wiper System

There are 385 Watt photovoltaic panels on Mehmet Akif Ersoy Anadolu High School’s roof (seeFigure 10 in Appendix H). There are 12 cells on the panel’s left and right side [23] and 3 LDRs (light sensors) are placed every three cells (see Figure 11 in Appendix H). LDRs’ signals are taken by the Arduino and according to the received signal, Arduino decides whether the panel is dirty and needs to be cleaned because if the panel is dirty [25], LDRs cannot get enough light so send 0s more than 1s to Arduino. If the panel is dirty, Arduino makes the wiper move down while cleaning water flows from the pipe which is on top of the panel (see Figure 12 in Appendix H) .

After one down-up movement, received signals are controlled again to check whether the panel is cleaned and if it is not cleaned enough, wipe moves down up again. The required cleaning brushdesigned for solar panel cleaning [27]. The LDRs-Arduino-Wiper electronic system is implementedby an electrical engineer, wiper and pipe are mounted on the panel by a mechanical engineer. LDR-Arduino Based Wiper System is implemented on each of 146 panels [4] on Mehmet Akif ErsoyAnadolu High School’s roof.

4.0  CRITERIA FOR ASSESSING SOLUTIONS

The following criteria were used to assess the proposed solutions: safety reliability [28], applicability[29] and cost [30].

4.1  Safety Reliability [28]

• Airobotics Solar Drone: Risk of the drone hitting [31], [32] or falling on someone [33] were
• Robsys RTM Series Solar Panel Cleaning Robot: Fall risk potential due to climbing up theroof to put the robot on the panels was inspected [34].
• LDR-Arduino Based Wiper System: Fall risk potential due to the system installation on thepanels on the roof was examined [35].

4.2  Applicability [29]

• Airobotics Solar Drone: Docking station installation [12] and drone’s monitoring systemapplicability [11] were
• Robsys RTM Series Solar Panel Cleaning Robot: The robot usability on the PSA were in termsof roof slope and panels’ order [18].
• LDR-Arduino Based Wiper System: Panels’ surfaces have fragile micro cells [36] so whetherthe designed system can be applied to the panels was checked.

4.3  Cost [30]

All three solutions’ affordability were be compared after evaluating the total cost of each [37].

• Airobotics Solar Drone: The drone, required cleaning water, shipping andimplementing costs were
• Robsys RTM Series Solar Panel Cleaning Robot: The robot’s price and shipping cost were
• LDR-Arduino Based Wiper System: LDRs’, wipers’, pipes’, Arduinos’, brushes’ pricesand their shipping costs were In addition, implementing cost were summed for all panels on the PSA.

5.0  RESEARCH METHODOLOGY

The solutions were checked against the criteria by the following research methods: literature review [38],market research [39], expert opinion [40] (see Appendix I).

• Literature Review [38]: All solutions were examined by literature review for applicability[11], [12], [13], [14], [41], [42], [43] and safety reliability [11], [13],[19] [42], [43], [44], [45].
• Market Research [39]: To specify each solution’s cost, market research was conducted [15],[46], [47], [48], [49], [50], [51], [52], [53]
• Expert Opinion [40]: Çağrı Canöz’s (employee in İklim Enerji which is a solar panelinstallation and AR-GE company [54]) opinions about proposed solutions’ safety reliability,applicability and cost were taken. Kübra Karabulut (sales support engineer in Robsys) was called to get detailed information about Robsys RTM Series Solar PanelCleaning Robot.

6.0  RESULTS AND ANALYSIS

Safety reliability, applicability and cost of all three solutions were assessed using the predetermined research methodology. Since the project mainly focused on a safety problem, safety reliabilitycriterion has the highest weight which is 40%. Applicability and cost criteria have 30% weight each. To assess each solutions’ safety reliability and applicability, separate checklists were used (see Table 3 and 4 in Appendix J). For cost assessment, each solutions’ total cost were calculated on a scale of 1-3 as X stands for the total cost:

1- X > 450.000 TL

2- 450.000 TL > X > 200.000 TL

3- 200.000 TL > X

6.1  Airobotics Solar Drone

See Table 5 and 6 in Appendix K for the drone’s safety reliability and applicability scores.

6.1.1  Safety Reliability

• Do people need to climb up the roof to clean the panels?

The drone can be controlled from anywhere inside of its range by its remote controller [13], [16], [17]; therefore, people do not need to climb up for cleaning.

• Do people need to climb up the roof for the installation? There isno component to install on the roof [12].
• Is there a possibility of hitting or falling on someone?

Yes, drone accidents such as hitting [31], [32] or falling on someone [33] may occuraccording to literature review. Therefore, the accident possibility is valid for Airobotics solar drone, too.

6.1.2  Applicability

• Is the system manufacturable [55]?

The drone was manufactured and it is used for cleaning solar panels. There are a number ofnews about the drone and the manufacturer on the internet [11], [15], [41].

• Is the PSA compatible with the installation of the solution [56]?

PSA is slightly compatible with the installation of the solution since for the docking station installation, a separate place needed in the school backyard [11], [12], [15]. In addition,computers in the school are not technological enough; therefore, the drone’s monitoringsystem cannot be installed on those computers.

• Is the system easy to use after it is installed?

According to Ç. Canöz, the drone and its docking station usage may be difficult tounderstand. In addition, according to literature review, since the drone is fully automated[11], [13], it may be difficult to control the docking station.

• Does a similar system exist [57]?

Similar solar panel cleaning drones are used [41], [42], [43].

• Is it easy to contact the maintenance service?

Yes, however the maintenance service is in abroad [11], it may be difficult to send the drone or its components if any problem occurs. In addition, it may be tough to call thetechnical service since communication needs to be in English. However, there is noadministrator who speaks English fluently in the school.

6.1.3  Cost

• Drone price: One drone is enough: 000$ [12] x 14.67 = 513.450 TL -Free shipping
• Softwash pump set : 02$ [46] x 14.67 = 2.010 TL -Free shipping
• Deionized pure water [53] price for per cleaning [47]: 30lt x 4 = 120lt

162,5 TL x 4 = 650 TL

Total cost is minimum 516.110 TL which is 1 point in cost scale.

6.2  Robsys RTM Series Solar Panel Cleaning Robot

See Table 7 and 8 in Appendix L for the robot’s safety reliability and applicability scores.

6.2.1  Safety Reliability

• Do people need to climb up the roof to clean the panels?

Yes, cleaning staff need to climb up the roof to clean the panels because the robot must be put on the panels [21]. However, according to K. Karabulut, the robot is controlled remotely socleaning staff does not need to move on the roof while cleaning the panels.

• Do people need to climb up the roof for the installation?

The robot has no component that requires to be installed on the roof.

• Is there a possibility of hitting or falling on someone?

According to K. Karabulut, the robot has 4 sensors so when it reaches the gap, it stops. Therefore,it cannot fall from the roof on someone.

6.2.2  Applicability

• Is the system manufacturable [55]

The robot was manufactured by Robsys and sold [20].

• Is the PSA compatible with the installation of the solution [56]?

The PSA is slightly compatible with the installation of the solution because the robot was designed for approximately 10 times larger solar panel facilities according to K. Karabulut.

• Is the system easy to use after it is installed?

It is easy to use the robot. According to K. Karabulut, after purchasing is completed,technical service demonstrates how to use the robot on the PSA.

• Does a similar system exist [57]?

The same robot is widely used on industrial roofs and solar power plants [18],[19],[20], [21].

• Is it easy to contact the maintenance service?

Yes, it is easy to contact the maintenance service. The company is interested in its customers.In addition, the company is in İstanbul [20], so it may not be as difficult for the technicalservice to arrive as abroad, if any problem in the robot is encountered

6.2.3  Cost

• Robot price: One robot is enough: ~27.500$ x 14.67 = 425 TL
  • Customer goes and takes the robot from the Robsys
• Fuel and highway toll cost: Distance between Robsys factory and PSA is approximately 500km [48] and approximate fuel usage is 30lt for a gasoline car, 16lt for a diesel car [49] .
  • Gasoline cost: 42.16lt [49] x 06 TL [50] x 2 = 1.607 TL ( for gasoline cars) 30lt [49] x 22.08 TL [50] x 2 = 1.324 TL (for diesel cars)
  • Highway toll: 50 TL [51] x 2 = 179 TL
• Deionized pure water [53] price for per cleaning [47]: 30lt x 4 = 120lt

162,5 TL x 4 = 650 TL

Total cost is minimum 406.720 TL which is 2 points in cost scale.

6.3  LDR- Arduino Based Wiper System

See Table 9 and 10 in Appendix M for the system’s safety reliability and applicability scores.

6.3.1  Safety Reliability

• Do people need to climb up the roof to clean the panels?

Cleaning staff do not need to climb up the roof for cleaning because the system cleans thepanels automatically when they get dirty [26].

• Do people need to climb up the roof for the installation?

Yes, the system installation should be done for each panel on the PSA [26] and since thepanels were mounted on the roof, people who implement the system need to climb up the roof for the installation. According to Ç. Canöz, the fall risk during the system installation on the PSA can increase due to high temperature on the panels’ surfaces and panels’ order which are very close to each other. However, he indicates that potential fall risk during the installation can be minimized by following 6331 Occupational Health and Safety Law.

• Is there a possibility of hitting or falling on someone?

Since the system will be mounted on the panels [26], there is no hitting or falling risk.

6.3.2  Applicability

• Is the system manufacturable [55]

The system was installed on solar panels by T. Kargacıoğlu in Afyon Kocatepe University [26].

• Is the PSA compatible with the installation of the solution [56]?

The PSA is highly compatible with the installation of the system. According to Ç. Canöz, required components for the system can be found easily and the system installation does not require too much workload. In addition, he indicates that the system is well designed so thereis no obstacle to install it on the PSA.

• Is the system easy to use after it is installed?

Since the system works automatically [26], it is easy to use according to Ç. Canöz.

• Does a similar system exist [57]?

The same system exists on two groups of solar panels in Afyon Kocatepe University [26].

• Is it easy to contact the maintenance service?

An electrical electronics engineer or a mechanical engineer can control the system if anyproblem is encountered.

6.3.3  Cost

The system will be installed each panel on the PSA (146 panels) [4]

• Cleaning brush: Total 145m [8], [26] brush needed. The cleaning brush is 1m [46]: 145 x (0.10$ x 14.67) = 212,7 TL [46] -Free shipping [46]
• Pipe: Panels’ total width is 144,54m [8], [26]. PPRC pipe is 2m [58] 75 x 62,72 TL [58] = 704 TL -Free shipping [58]
• Arduiono: 140,41 TL [59] x 146 = 498,4 TL -Free shipping [59]
• LDR: 24 LDR requires for each panel [26]

24 x 146 x 1.12 [60] = 3.924,5 TL -Free shipping

• Micro DC motor reductor: 146 x 2 TL [52] = 11.242 TL – 562,1 TL discount = 10.679,9 TL
• Deionized pure water [53] price for per cleaning [47]: 30lt x 4 = 120lt 162,5 TL x 4 = 650 TL
• Installation cost: 20.000 TL

Total cost is minimum 50.000 TL which is 3 points in cost scale.

7.  CONCLUSION AND RECOMMENDATIONS

Assessment of all three solutions in terms of the chosen criteria was given in Appendix N.

7.1  Conclusion

• Enough information about Airobotics Solar Drone’s cost could not be reached since thecompany did not reply to the mails sent to get detailed cost However, even thedrone’s price is enough to score it under cost scale.
• Robsys RTM Series Solar Panel Cleaning Robot became the second in terms ofapplicability criterion. The robot was designed for larger solar energy facilities;therefore, its price is high for the
• LDR- Arduino Based Wiper System scored the highest in terms of applicability and cost Therefore, it was found to be the optimum solution.

7.2  Recommendations

For LDR- Arduino Based Wiper System installation, it is recommended that:

• Required safety precautions should be taken for the people who install the system on the
• After the installation, panels’ microcells should be controlled since they may bedamaged during the
• Designed circuit should be placed where it will not get wet due to the cleaning process or rain because if it gets wet, short circuit possibility may occur [61].

7.3  Action Plan

The following steps will be pursued for LDR- Arduino Based Wiper System installation:

• Required components will be
• The circuit will be designed and embedded into Arduino by an electrical electronics
• The system hardware will be designed and mounted on the panels by a mechanical
• Microcell damage control will be
• Whether the installed system works or not will be Ganttchart for the action plan was given in Appendix O.

APPENDICES

Appendix A: Dirty Solar Panel

Figure 1. Dirty Solar Panel [2]

Appendix B: Power Output Change After Solar Panel Cleaning

Table 1: Power Output Change After Solar Panel Cleaning [3]

Appendix C: Mehmet Akif Ersoy Anadolu High School’s Roof

Figure 2. Mehmet Akif Ersoy Anadolu High School’s Roof [8]

Appendix D: Solar Panel Cleaning in Mechanical Way

Figure 3. Solar Panel Cleaning in Mechanical Way [9]

Appendix E: Solar Panel Order on Mehmet Akif Ersoy Anadolu High School Roof

Figure 4. Solar Panel Order on Mehmet Akif Ersoy Anadolu High School Roof [10]

Appendix F: Airobotics Solar Drone and Its Components

Figure 5. Airobotics Solar Drone [11]

Figure 6. Airobotics Solar Drone’s Docking Station [14]

Figure 7. Inside of the Docking Station [14]

Appendix G: Robsys- RTM Series Solar Panel Cleaning Robot and Its Components

Figure 8. Robsys- RTM Series Solar Panel Cleaning Robot [18]

Figure 9. Robsys- RTM Series Solar Panel Cleaning Robot’s Remote Controller [19]

Appendix H: LDR- Arduino Based Wiper System

Figure 10. Photovoltaic Panel Used in the Pilot Study Area [23]

Figure 11. LDR- Arduino Based Wiper System Schematic [24]

Figure 12. LDR- Arduino Based Wiper System Design [26]

Appendix I: Research Methodology Coverage

Table 2: Research Methodology Coverage

Appendix J: Checklists

Table 3: Safety Reliability Checklist

Table 4: Applicability Checklist

Appendix K: Airobotics Solar Drone’s Assessment

Table 5: Airobotics Solar Drone’s Safety Reliability

Table 6: Airobotics Solar Drone’s Applicability

Appendix L: Robsys- RTM Series Solar Panel Cleaning Robot’s Assessment

Table 7: Robsys- RTM Series Solar Panel Cleaning Robot’s Safety Reliability

Table 8: Robsys- RTM Series Solar Panel Cleaning Robot’s Applicability

Appendix M: LDR- Arduino Based Wiper System’s Assessment

Table 9: LDR- Arduino Based Wiper System’s Safety Reliability

Table 10: LDR- Arduino Based Wiper System’s Applicability

Appendix N: Solutions’ Overall Assessment

Table 11: Solutions’ Overall Assessment

Appendix O: Gantt Chart

Table 12: Action Plan Gantt Chart

9.0 REFERENCES

•