impact of soiling on pv module performance for … of soiling on pv module performance for various...

Impact of Soiling on PV Module

Performance for Various Climates 4th PV Performance Modelling and Monitoring Workshop

22/23 October 2015, Cologne, Germany

Dr Werner Herrmann TÜV Rheinland Energie und Umwelt GmbH

51101 Cologne, Germany

[email protected]

http://www.tuv.com/solarpower

Outline

Introduction

PV-KLIMA test locations

Experimental approach

Results:

Angular impact on soiling loss

Soiling patterns for different climates

Impact of periodical cleaning

Summary

26.10.2015 2 4th PV Performance Modelling and Monitoring Workshop


Introduction – PV power loss due to soiling

26.10.2015 3

Dust deposition on the PV module surface is a complex phenomenon, which is

mainly influenced by the environmental/weather conditions, mounting principle

and glazing characteristics.

Performance losses are site-specific and can strongly depend on O&M work.

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4th PV Performance Modelling and Monitoring Workshop


Installation conditions

Non-uniform soiling,

glazing characteristics

Surrounding environment

Climatic impacts

PV-KLIMA Project

Comparative energy yield testing of PV modules

Location Country Operation since Köppen-Geiger climate classification

Ancona Italy 01 Nov 2013 Cfa (mediterranean)

Tempe Arizona/USA 15 Dec 2013 Bwh (hot dessert)

Chennai India 01 Feb 2014 Aw (tropical savanna, hot-humid/dry)

Cologne Germany 01 Mar 2014 Cfb (temperate)

Thuwal Saudi-Arabia 11 Mar 2015 Bwh (hot desert, sandstorm impact)

26.10.2015 4

Chennai Ancona Cologne Tempe

Saudi

Arabia



PV-KLIMA Test Locations

:

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Tempe / Arizona Chennai / Southeast India

2)

http://www.chennai.climatemp

s.com/

Location TUV Rheinland PTL, LLC

Tempe, AZ 85282

TUV Rheinland (India) Pvt. Ltd.

Chennai 602117, India

Geographical position: 33.4°N / 111.9°W

358 m above sea level

13°N / 80°E


Inclination angle 33.5° 15°

Annual in-plane global

solar irradiation

2360 kWh/m²

1860 kWh/m²

Average annual rainfall 219 mm 1597 mm

Surrounding

environment

industrial area,

no vegetation

Rural environment,

Farm land




:

26.10.2015 6

Cologne / Germany Ancona / Italy

Location TUV Rheinland Group

51101 Cologne, Germany Loccioni

60030 Angeli di Rosora, Italy

Geographical position: 50.6°N / 7.0°E 53 m above sea level

13°N / 80°E


Inclination angle 35° 35°


solar irradiation

1195 kWh/m²

1556 kWh/m²

Average annual rainfall 774 mm 757 mm

Surrounding

environment

Urban environment,

Flat roof of 5 storey building

Hilly landscape with grassland

and forest, agricultural use



:

26.10.2015 7

Thuwal / Saudi-Arabia

Location KAUST, NEO

Thuwal, Saudi-Arabia

Geographical position: 22.3°N / 39.1°O 3 m above sea level

Inclination angle 25°


solar irradiation

23861) kWh/m²

1) Extrapolation from 204 days

Average annual rainfall 70 mm

Surrounding

environment

University ground, coastal

environment




Experimental Approach

Measurement of soiling rate

26.10.2015 8

Side-by-side irradiance measurement with two mini-modules:

Standard PV glazing, center cell operated in short circuit (reference cell)

Data recording interval: 30 seconds

Soiling loss = Transmission loss Lower effective irradiance reaching the cells

Soiling loss factor (SLF) = Ratio of irradiances from “clean” and “dirty” cell

“Clean” mini-module “Dirty” mini-module

𝐺𝐸𝐹𝐹 = 𝐼𝑆𝐶,𝑀𝐸𝐴𝑆/𝐼𝑆𝐶,𝑆𝑇𝐶 × 1 + × (𝑇𝑀𝑂𝐷 − 25°𝐶) × 1000 𝑊/𝑚²

𝑆𝐿𝐹 =𝐺𝐸𝐹𝐹,𝐷𝑖𝑟𝑡𝑦

𝐺𝐸𝐹𝐹,𝐶𝑙𝑒𝑎𝑛



Results

Angular impacts on soiling loss

26.10.2015 9

Dust accumulation on the glass surface changes its angular response

Soiling loss depends on the angle of incidence (AoI) of direct sunlight

Soiling loss due to AoI effects can be significant

Tempe: -0.8% annual soiling loss is caused by angular transmission losses

in the range AoI >30°

W. Herrmann, M. Schweiger: Soiling and self-cleaning of PV modules under the weather conditions of two locations in

Arizona and South-East India, IEEE-PVSC42, New Orleans, USA, 2015



Results

Soiling pattern for Tempe/Arizona: Dec 2013 – Sep 2015

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Average daily

SLF decrease in

dry periods:

-0.08% to -0.22%

Annual soiling loss

(year 1):

-3.7% total loss

-0.8% angular loss

Annual soiling loss

(year 2*):

-1.4% total loss

Single rainfall events Effective cleaning: SLF recovery >99% observed

Significant differences in soiling patterns for 1st and 2nd year frequency of

rainfall, dust accumulation rate



Results

Soiling pattern for Chennai/India: Feb 2014 – Sep 2015

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Average daily

SLF decrease in

dry periods:

-0.12% to -0.39%

Annual soiling loss

(year 1):

-2.2% total loss

3-months dry season 25% soiling loss observed

Recovery in rainy season: SLF >99% in first year, SLF >98% in second year

Significant differences in soiling patterns for 1st and 2nd year



Results

Soiling pattern for Ancona/Italy: Nov 2013 – Sep 2015

26.10.2015 12

Daily SLF decrease:

Not applicable

Annual soiling loss:

0,04% (Year 1)

0,02% (Year 2)

High cleaning effectiveness due to rainfall during the whole year

Comparable soiling patterns for 1st and 2nd year ±1% SLF variation



Results

Soiling pattern for Cologne/Germany: Mar 2014 – Sep 2015

26.10.2015 13

Daily SLF decrease:

Not applicable

Annual soiling loss:

-0,16% (Year 1)

+0.17% (Year 2*)

High cleaning effectiveness due to rainfall during the whole year

Comparable soiling patterns for 1st and 2nd year ±2% SLF variation



Results

Soiling pattern for Thuwal/Saudi-Arabia: Mar 2015 – Sep 2015

26.10.2015 14

Corresponding wet cleaning of “dirty” mini-module Reset SLF = 1

Experimental approach

for Thuwal test site:

Periodical mechanical

cleaning of the PV module

surface with rotating

brushes (Type NOMADD)



PV installations in desert climate (i.e. MENA region) require periodical

cleaning of PV module glass surface to optimize the energy yield

Results

Soiling pattern for Thuwal/Saudi-Arabia: Mar 2015 – Sep 2015

26.10.2015 15

High ambient dust concentration Average daily percent decrease of SLF = -0.5%

Dust storm Max. SLF change per day = -7.7%



Summary 1/3

Measuring results

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Average

annual

rainfall1)

Annual transmission

loss due to soiling

(Year 1)

Average SLF

decrease

between rainfall

events

Max. daily

SLF

decrease

Tempe /

Arizona

219 mm Year 1: -3.7%

Year 2: -1.4% 2)

-0,15% per day -1.8%

Chennai /

India

1597 mm Year 1: -2.1%

Year 2: -7.5% 2)

-0,2% per day -2.2%

Ancona /

Italy

757 mm negligible N/A -0.4%

Cologne /

Germany

774 mm negligible N/A -1.1%

Thuwal /

Saudi-Arabia

70 mm N/A

Periodical cleaning

-0.5% per day -7.7%



1) http://de.climate-data.org 2) Measuring data of year incomplete

Summary 2/3

Principle effects

17 26.10.2015

Self-cleaning effect:

Rainfall leads to nearly full recovery of PV module performance.

Permanent soiling can occur if humidity condensate sticks dust to the surface

or can be caused by algae growth.

Soiling pattern:

Great variation in daily percent decrease of soiling loss factor (SLF) makes

soiling loss prediction difficult in tropical and arid climates

Broader data basis required



Summary 3/3

Impact of soiling for various climates

18 26.10.2015

Hot-dry climate:

Tempe: Moderate dust settlement between periodic rainfall events leads to

annual performance loss <4%

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.

Hot-humid/dry climate:

Chennai: Considerable dust settlement during 3-months dry season can lead to

substantial soling loss. Cleaning during dry season must be considered to

improve the performance of a PV power plant.

Temperate and Mediterranean climate:

Ancona, Cologne: No measureable performance loss due to frequent rainfall.



Thank you for your attention!

[email protected]

http://www.tuv.com/solarpower

Work was partially funded by the German Federal Ministry for Economic

Affairs and Energy (BMWi) under contract No. 0325517B.

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