The Challenges Of Developing Robotic Solar Panel Cleaning System · 2019-11-04 · Key Findings Soiling losses were found to be 0.21% per day.The site was observed to have a decrease

The Challenges Of Developing Robotic Solar Panel Cleaning System

Why Do We Need To Clean Solar Panels ? 01

Where do we need robotic solar panel cleaning system? 02

03 Why is waterless robotic cleaning the first choice ?

www.bosonrobotics.com

Why Do We Need To Clean Solar Panels ?

• Substantial Energy Gain

• Maximizing Solar Panel Life Cycle By Reducing Heat Spots

Soiling Distribution Map Of The World

Automated cleaning system can deliver averagely

11% energy gain annually for utility solar farms in areas with sufficient solar radiation


Results of decades of scientific research and experiments


1994 Effect of Dirt on

Transparent Covers in

Flat-plate Solar Energy

Collectors. Solar Energy

By Garg H.

2003

Effect of dust

deposition on the

performance of a solar

desalination plant

operating in an arid

desert area. Solar Energy

By Garg H.

2006 The Effect of Soiling on

Large Grid-Connected

Photovoltaic Systems in

California and the

Southwest Region of the

United States. IEEE 4th

World Conference

By Monto M, Rohit P.

2010

Impact of Dust on Solar

Photovoltaic (PV)

Performance: Research

Status, Challenges and

Recommendations

By Kimber A, Mitchell L, Nogradi S, Wenger H


The effect of dust on solar photovoltaic systems

2013

By F. Mejia, J. Kleissl, J. L. Bosch

Center for Renewable Resources and Integration, Department of Mechanical and Aerospace Engineering, University of California, San Diego

Key Findings

Soiling losses were found to be 0.21% per day. The site was observed to have a decrease in efficiency

from 7.2% to 5.6%（22% efficiency loss） during a 108 day dry period in the summer at which point

a rain event occurred that recovered most of the lost efficiency going back to 7.1%.

If an automated cleaning system was installed to clean the sites regularly, larger energy gains would be

possible, on average 11.1% of annual energy.


11.1%

Soiling Problems Are Even Bigger In Middle East Areas

USGS Sand Storm Map

Sand storm seen from space


By Shaharin Anwar Sulaimana, Atul Kumar Singhb, Mior Maarof Mior Mokhtara, Mohammed A. Bou-Rabeec

Department of Mechanical Engineering, Universiti Teknologi Petronas, 31750 Tronoh, Perak, Malaysia

Department of Engineering Design, Indian Institute of Technology, Madras, India

Public Authority for Applied Education &Training, Department of Electrical Engineering, College of Technological Studies, Kuwait

Joint Study on PV Panel Soiling problems by researchers from multiple nations


2014

Influence of Dirt

Accumulation on

Performance of PV

Panels

Key Findings


Flat panels are much

more susceptible to soiling

effects

4g/m2 dust layer on panel

decreases output by

600

250

150

00

17% Reduction

64% Reduction

Saudi

India

40%

Kuwait

17% energy reduction

in 6 days

Roorkee

8% energy reduction

in 10 days

Riyadh

32% energy reduction

in 8 months

Tilt 250 Tilt 250 Tilt 450

It was found that the external

soiling could reduce the

photovoltaic performance by

up to 85% up to 85%

It was found that the external

soiling could reduce the

photovoltaic performance by

Rain drop is not always sufficient for natural cleaning

Accumulated contamination

at the panel corners At least 20 mm rainfall is needed to clean the surface of PV system,

otherwise the system will continue to experience power loss due to the

dust and soil disposition.


Key Findings

For light radiation of 310 W/m², the output power of the solar panel reduced by:

between 9% and 31% due to the effects of presence of talcum ,

between 60% and 70% due to dust ,

between 70% and 80% due to sand , and

between 77% and 83% due to moss .

2015

Thuwal: Considerable dust settlement and missing rainfall lead to substantial annual performance

loss >50% , which requires periodical cleaning for economic operation of a PV power plant. www.bosonrobotics.com

4th PV Performance Modeling and Monitoring Workshop

Location

Ave. annual rainfall

Average SLF decrease between

rainfall events

Max daily SLF

derease

Thuwal/ Saudi-Arabia

70 mm -0.5% per day -7.7%

Impact of Soiling on PV Module Performance for Various Climates

By Dr Werner Herrmann TÜV Rheinland Energie und

Umwelt GmbH

Life of solar panels will be greatly shortened without proper cleaning due to aggregation of energy loss over time and occurrence of hot spots


Non-compliance to clean the modules, pollution is

increasing and losses rising

Bird drops easy to cause hot spots,

damaging the whole panel quickly

Key Findings

A Climate / Soiling (Pollution) Matrix

Where do we need robotic solar panel cleaning system?

K4:

Coastal Climate

Annual rainfall 800-900mm

Highly salty mist with contaminants and corrosive effect

K3:

Extremely dry, semi-arid and desert climate

Annual rainfall below 300mm

K2:

Dry Summers, continental climate

Annual rainfall 450-550mm

Summer season very dry

(Including Hungary and South part of Romania)

K1:

Temperate and humid climate

Annual rainfall >800mm

Precipitation is relatively evenly distributed through a year

The categories by climatic parameters (K)

Spring Summer Autumn Winter





The categories by pollution intensity and frequency of cleaning needs (S)

S1: Solar system with moderate exposure to pollutant effect

The number of pollution sources and their polluting effect is small

Rains occurring throughout the summer, washing away a significant amount of soiling

Cleaning up occasionally, only 1-2 times a year

S4: Areas subject to extremely high contamination

Pollution from multiple sources impacts intensively

Significant amount of soiling ingredients strongly increase energy loss

Semi-desert and arid areas with frequent sand storms (Large amount of sands on solar cell surfaces

causes a significant performance loss)

Very frequent cleaning required, weekly at least

S2: Medium-intensity pollution areas

The given solar system is positioned away from the sources of pollution (industrial, agricultural activities

and traffic of the roads)

Considering the partial cleaning effects of rains, usually quarterly cleaning is enough

S3: Areas where the solar system is subject to heavy soiling

A lot of soiling sources nearby the solar system (Significant industrial, agricultural activities and road

traffic, migratory birds zone)

Cleaning effects of rain only marginal

Need to be cleaned every month


!

!

!

!


The Climate / Soiling (Pollution) Matrix

Why is waterless robotic cleaning the first choice ?


Standard high

efficiency solar panel :

about 2 sq m

8 bottles per panel !

Manual Cleaning and

water tank use

3.5-5 L water/ M2

for cleaning 370 W Panels

A 50MW utility solar farm

will averagely uses a full

swimmingPool for

cleaning once:

1,100 tons of water

8L

What makes a viable robotic solar panel cleaning system ?

BOSON robotic

Reliable Efficient SCADA Weather

Resistance Durable

Has to be light weighted

to minimize the force exerted on

panels during operation

？ www.bosonrobotics.com

The main structure has to be

impervious to corrosion

for decades to match the lifetime

of a solar farm

No brittle fracture during

drastic temperature variation between

seasons since it is supposed to move

at a speed anytime during a year

1 2

3

too heavy, rusting

Steel Stainless Steel Aluminum alloy

too heavy, difficult to process, expensive

too soft, low structure strength

Challange

Solution : Metallurgical technology


1. Liquid forged parts of aluminum alloy

2. To enable the aluminum structure as

strong as steel one but only 1/3 of the

steel weight

3. Aluminum frames hardened after heat

treatment ( T5 + T6 )


Finer dust particles are bigger trouble for solar panel and for its cleaning robots as well…….

Ball bearing Grease Lubrication Chain and cable system ？

Challange

Most of us think all dusts are equal, but actually some are far more equal than others

Solution :Material Science

Non-metal bearing system, self

lubrication

Micro grooves to drive fine dust

particles out of bearing system

during movement , can weather

the continued sand storms

without maintenance.


Even connected, the gaps between solar panel plates with various angel and height difference are formidable

obstacles for robotic movement

Connection between gaps must not pose a treat to panel structure.

Challenge : Moving On Unfriendly Terrain


A sophisticated smart AWD system(ALL Wheel Drive) to ensure the robotic cleaning system to adjust its posture and movement to match the topography of gap connectors

Solution : Smart Electronic Control algorithum

video

video

video

video

Like an orchestral conductor conjuring up the most beautiful music without sounding a note himself, the smart control algorithum acts as the nerve of the robot to nevigate it across the unpredictable gaps between solar panel tables

Challenge : Battery Pack

Harsh outdoor environment damages the battery quickly, leading to very short battery life. Replacement difficult

？

650

-350


Challange

Solution : High Weather-Resistant Battery Pack and Smart Battery Health Supporting System

Sophisticated BMS (battery

management system) to manage

charging and discharging in a smart way

-350C-650C

1C charging and

discharging ability

between


video

Untethered power enable

the robotic cleaning system

to work effectively everyday.

Drastically varied radiation leads

to fluctuating charging voltage

Temp variation requires matching charging conditions

Days of no charging

drains the battery and

kill it

Unmatched charging

parameter damages

the charger and battery

No existing solar charger could solve all the above problems, posing a threat to energy storage and battery life, causing default of the whole robotic cleaning system ？

Challange

Sound

Solution : A Smart MPPT Solar Charger with temp and radiation level compensation


Can keep

charging during

consecutive

cloudy days

To maintain a healthy

charging condition to

protect the battery

Input Voltage: 36V~50V

Output Voltage: 12V 24V

Battery type: Lead acid Lithium battery

Output Power (MAX): 250 W

Maximum Current: 10A

Brush (Cleaning) System Omnipotent or Customized ?

Tiny sand grains, rocks. Leaves, sticks on panels Need to be pushed away before applying rolling brush

＋

Strip Brushes

Need a separate brush system to tend the soiling piled on corner

Solution: Customized bushing

system according to actual needs

Soft brushes can not clean sticky

contaminants and easy to get

braided and knotted with dampness

Replacing with different brush fiber

Water Cleaning Module

Challenge Solution


Steep corners between panel plates

＋

Challenge : O & M of Robot Fleet in Large Area

Data communication in solar

farms are difficult due to severe

electromagnetic interference by

substations and numerous power

equipments

Robots scattered in solar farm of

huge size, need to track the

performance of every key parts

(battery, motors and brushes) to

provide good O&M services


Need to link weather info to avoid

disastrous climate for safe

concern and intelligently decide

best cleaning time to maximize

power output

Solution : Robotic Cleaning System Cloud SCADA Platform and On-Site Monitoring and Control Software

站端系统操作视频播放

云端总部系统操作视频播放

找赵晶录视频，英文版，高清


video video

Ability of Crosover Collaboration and Supply Chain Integration

Materials Science

Mechanical structure

& Processing

Industrial Electronic Control System

Battery and Off-line

Charging System

Communication and Software Systems

High Reliable Panels Robotic

Cleaning System

Liquid forging, Nonmetallic

Bearing, Phase Change

Filling Materials

Whole Aluminum

Structure

Mater IC & Posture

Correction System

High weather resistance

battery system & Hight efficient

MPPT charge system

IOT cummunication

and SCADA cloud

center

Not unlike e-car design, Design of solar panel cleaning robot is not a solo play of one specific technology, but an ensemble of various technologies combined properly.


The Symbiosis of panel cleaning robots and solar farms. To keep solar panels clean and productive, let robots do the worry.

Documents

The Challenges Of Developing Robotic Solar Panel Cleaning System · 2019-11-04 · Key Findings Soiling losses were found to be 0.21% per day.The site was observed to have a decrease