choosing the optimal technology for hot climates to ... · chennai india 01 feb 2014 aw (tropical...

Energy Rating of PV Modules: Choosing the Optimal Technology for Hot Climates to Increase the Return on PV Investment

Joseph Nader, Markus Schweiger

TÜV Rheinland Energy GmbH, Cologne, Germany

[email protected], [email protected]

Intersolar Middle East, September 26-27, 2017, Conrad Dubai, UAE2

TÜV Rheinland – Business Solutions for Solar Energy Worldwide

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� 250 Solar Experts

� 6 accredited PV Laboratories

� 5 Outdoor Test Sites

� No 1 in PV module and component testing worldwide

� 35 Years experience in PV product testing

� >20GW experience in Power plant inspections

Quality, safety and reliability

around the world

Our global network for PV testing:


� Inspections of technical equipment, products and services

� Overseeing PV projects worldwide

� Helping to shape processes

� Participation in IEC standardization committees

� Research and development in the area of power plant optimization and module qualification

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TÜV Rheinland – Business Solutions for Solar Energy Worldwide

Count on our experience for technical risk mitigation in PV investments: TÜV Rheinland, as independent Third Party, has been working with the financial industry, investors, and operators worldwide for decades. TÜV Rheinland has the experience to guide your PV projects from inception, planning, PV supply chain management, construction, commissioning, to O&M and re-sale.


Agenda: Energy rating of PV modules

1. Introduction: power vs. energy rating

2. Relevance for utility scale PV investments

3. Impact factors and underlying data base

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4. Performance of market ready PV modules and emerging technologies

5. Conclusions


Introduction: Energy rating of PV modules

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Current situation – limitations of power rating:

� Pricing €/WP of PV modules is based on their power rating measured at standard test conditions (STC)

� Real operating conditions are significantly different to STC (1000W/m², 25°C, AM1.5)

� The various PV module technologies available at the market have significantly different physical properties regarding performance at different operating conditions

� Energy yield predictions using software simulation tools show limited accuracy due to non-adapted physical models and insufficient input data

Not everything you should know about PV module performance behavior is written on the labels or datasheets



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30%STC



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Energy rating – what does it mean:

� Means to rate PV modules according to predictive output energy (yield) in €/Wh rather than to deficient power in €/WP measured at STC only

� The aim is to find the best performing technology for a certain location After all the product solar industry produces is energy not power

� Normative basis are the series of standards according to IEC 61853 part 1 to 4 which are not technically mature nor published yet

� An advanced energy rating is able to tell you exactly the prospective energy yield and the reasons for differences in energy yield performance of emerging PV module technologies in percentage

It means lower risks, better bankability, more revenue on PV investments, higher net profit for ultimate owner of power plant


Motivation: Energy rating of PV modules

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Why is energy rating beneficial for PV industry - the global context:

� between 2004 - 2016 a sum of $1,161 billion was invested in PV systems

� approximately 250GW of PV capacity is installed worldwide

� By 2050 a globally installed PV capacity of around 4.6 TWP is expected

� This implies a global investment market of $225 billion per year on average

For the upcoming multi-GW installations of 125GW/year on average, each percentage of uncertainty results in significant investment uncertainty with regard to capital expenditures.


Motivation: Energy rating of PV modules

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� 100 MW solar park project in UAE

� Specific energy yield of 1800 kWh/kWp

� Levelised cost of electricity at $100/MWh

� +1 more yield means +$4.5 million revenue after 25 years of operation (emerging interest earnings not considered)

� We measured up to 25% difference in Wh/WPusing PSTC as stated by the manufacturers

State-of-the-art energy rating and energy yield measurements are a smart opportunity for investors to increase their revenues!

Why is energy rating beneficial for PV industry – a quick example:


� Since 2013 several test sites constructed

� 5 test-sites under operation of TÜV Rheinland

� 15 module types investigated in detail

� 2018 new test site in Huhehot (Mongolia)

Huhehot

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Cologne

TempeChennai

Thuwal

Ancona

Energy rating of PV modules: Impact factors and underlying data base

Intersolar Middle East, September 26-27, 2017, Conrad Dubai, UAE11 27.09.2017

Location Country Operation

since

Köppen-Geiger climate classification

Inclination angle

Annual in-plane global solar irradiation

Average annual rainfall

Annualtransmission loss

due to soiling

Ancona Italy 01 Nov 2013

Cfa (mediterranean) 35° 1556 kWh/m² 757 mm negligible

Cologne Germany 01 Mar 2014

Cfb (temperate) 35° 1195 kWh/m² 774 mm negligible

Chennai India 01 Feb 2014

Aw (tropical savanna, hot-humid/dry)

15° 1860 kWh/m² 1597 mm

Year 1: -2.1%Year 2: -7.5%

Tempe Arizona/USA

15 Dec 2013

Bwh (hot desert) 33.5° 2360 kWh/m² 219 mm Year 1: -3.7%Year 2: -1.4%

Thuwal Saudi-Arabia

11 Mar 2015

Bwh (hot desert, sandstorm impact)

25° 2386 kWh/m² 70 mm -0.55%/day(periodical cleaning)

H

O

T

!Energy rating of PV modules: Impact factors and underlying data base


13 %

12 %

21 %

23 %

25 %

25% more (or less) energy in Thuwal per stated W P

Module Performance Ratio (MPR)

Energy rating of PV modules


What affects the energy rating of PV modules:The MPR of a PV module depends on the module technology, its mounting situation, and the

location. The location implies climatic conditions with characteristic variations of irradiance,

temperature and spectral distribution of sun light, all occurring on seasonal and daily basis.

Technology driven factors are:

1. Temperature coefficients

2. Operating temperature

3. Spectral response

4. Low irradiance behavior

5. Angular response

6. Nominal power and its stability

7. Soiling

Energy rating of PV modules: Impact factors


GPoA > 15 W/m²

Energy rating of PV modules: Influence of temperature


LocationAmbient temperature

range (G > 15 W/m²)Average

Cologne

(Germany)-4.6 °C to 34.1 °C 15.2 °C

Ancona

(Italy)-1.3 °C to 35.5 °C 18.1 °C

Chennai

(India)17.0 °C to 42.7 °C 30.3 °C

Tempe

(USA)-0.5 °C to 44.8 °C 27.4 °C

Thuwal

(Saudi-

Arabia)

13.2 °C to 44.3 °C 31.1 °C



LocationModule temperature

range (G > 15 W/m²)Average

Cologne

(Germany)-7.5 °C to 60.4 °C 21.5 °C

Ancona

(Italy)-4.3 °C to 59.4 °C 25.6 °C

Chennai

(India)14.1 °C to 69.8 °C 41.1 °C

Tempe

(USA)-5.1 °C to 68.4 °C 39.6 °C

Thuwal

(Saudi-

Arabia)

10.2 °C to 68.6 °C 41.8 °C



Temp. differences

within modules at

same location:

3.4 °C in Chennai,

5.0 °C in Tempe,

4.9 °C in Ancona,

3.7 °C in Cologne

6.5 °C in Thuwal

∫

∫=

T

PoA

T

PoABoM

GBoM dtG

dtGT

T,



Test-siteEnergy yieldloss due totemperature

Cologne -1.2 % to -3.7 %

Ancona -2.6 % to -5.3 %

Chennai -5.3 % to -9.6 %

Tempe -5.1 % to -10.6 %

Thuwal -5.2 % to -11.1 %

°−=∆∫

∫C

dtG

dtGTMPR

T

PoA

PoABoM

TTEMP 25γ



Factor soiling losses:

� depend on average local soling rates (-0,55/d in Thuwal), cleaning concept and one-off events like sand storms or rain

� From the energy rating perspective differences due to front glass technologies can be significant

� ARC coatings with anti-soiling technologies can improve average light transmission

� Higher dust settlement for structured glass detected �

Sta

ndar

d gl

ass

AR

coa

ted

Dee

p te

xtur

edEnergy rating of PV modules: Soiling


Performance of market ready PV modules and emerging technologies

Further energetic relevant aspects which can be quantified for different module types and locations:

Example 1: Offset of stated nominal power

Example 2: Rising nominal power and low irradiance losses in winter

Example 3: Metastable nominal power, lower temperature losses and spectral gains in summer

Example 4: Degradation of nominal power, spectral gains compensate temperature losses in summer

Emerging technologies: Bifacial PV modules show higher performance ratio. Advantage in energy yield depends on ground albedo and bifaciality factor.

1.

2.

3.

4.


Conclusions

�Varying climatic conditions across markets and the individual characteristics of PV technologies undermine accurate predictions of module energy yield using conventional methods.

�Real world working conditions of PV modules differ from STC.

�Most dominant for harsh desert climates are temperature related losses: besides the temperature coefficients the average operating temperature is crucial.

�Emerging technologies as bifacial, thin-film and high-efficiency provide chances to increase the earnings of a power plant.

�Sophisticated energy rating can be done based on laboratory measurements and reference climate data sets. Operating temperatures and PSTC stability must be measured in the field.

�The competitiveness of solar projects can be enhanced by PV modules with reliable long-term performance and optimal energy yield performance suited to the climate of the installation location.

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References

(1) M. Schweiger, U. Jahn, W. Herrmann: Factors Affecting the Performance of Different Thin-Film PV Technologies and Their Impact on the Energy Yield, 26th European Photovoltaic Solar Energy Conference and Exhibition, September 2011, Hamburg, Germany.

(2) M. Schweiger, M. Ulrich, I. Nixdorf, L. Rimmelspacher, U. Jahn, W. Herrmann: Spectral Analysis of Various Thin-Film Modules Using High Precision Spectral Response Data and Solar Spectral Irradiance Data, 27th European Photovoltaic Solar Energy Conference and Exhibition, September 2012, Frankfurt, Germany.

(3) M. Schweiger, S. Michalski, U. Jahn, W. Herrmann, U. Rau: Non-Linearity of Temperature Coefficients, Equivalent Cell Temperature and Temperature Behaviour of Different PV-Module Technologies, 28th European Photovoltaic Solar Energy Conference and Exhibition, September 2013, Paris, France.

(4) M. Schweiger, M. Herz, S. Kämmer, W. Herrmann: Fabrication Toler-ance of PV-Module I-V Correction Parameters for Different PV-Module Technologies and Impact on Energy Yield Prediction, 29th European Photovoltaic Solar Energy Conference and Exhibition, September 2014, Amsterdam, Netherlands.

(5) M. Schweiger, W. Herrmann: Energy rating label for PV modules to improve energy yield prediction in different climates, 30th European Photovoltaic Solar Energy Conference and Exhibition, September 2015, Hamburg, Germany.

(6) M. Schweiger, U. Jahn, W. Herrmann: Bestimmung der Nennleistung von Dünnschicht-Modulen, 7. Anwenderforum Dünnschicht Photovoltaik, Februar 2011, Kloster Banz, Bad Staffelstein.

(7) M. Schweiger, T. Nolden, G. Mathiak: Potentialinduzierte Degra-dation (PID) bei kristallinen PVModulen, 27th Symposium Photovoltaische Solarenergie, 2012, Kloster Banz, Bad Staffelstein.

(8) M. Schweiger, L. v. Pidoll, U. Jahn, W. Herrmann: Vorkonditionie-rung, Stabilisierung und Metastabilität von Dünnschicht-PV-Modulen, 2013, Kloster Banz, Bad Staffelstein.

(9) M. Schweiger, C. Wesseling, W. Herrmann: Produktionsbedingte Streuung von Leistungsparametern unterschiedlicher PV-Modultechnologien, 2014, Kloster Banz, Bad Staffelstein.

(10) M. Schweiger, T. Neumann, S. Bröker, W. Herrmann: Vergleich von PV Modul Ertragsmessungen an Standorten in vier verschiedenen Klimazonen, 2015, Kloster Banz, Bad Staffelstein.

(11) M. Schweiger, S. Michalski, U. Jahn, W. Herrmann, U. Rau: Non-Linearity Of Temperature Coefficients, Equivalent Cell Temperature And Temperature Behaviour Of Different PV-Module Technologies, 2013, 39th IEEE Photovoltaic Specialists Conference, Tampa, Florida.

(12) M. Schweiger, W. Herrmann: Comparison of Energy Yield Data of Fifteen PV Module Technologies Operating in Four Different Climates, 2015, 42nd IEEE Photovoltaic Specialists Conference, New Orleans, Louisiana.

(13) M. Schweiger, W. Herrmann: Electrical Stability of PV Modules in Different Climates, 2016, 43rd IEEE Photovoltaic Specialists Conference, Portland, Oregon.

(14) M. Schweiger, W. Herrmann: Electrical Characteristics of Bifacial PV Modules Measured in the Laboratory, 2016, 26th Photovoltaic Science and Engineering Conference, Singapore.

(15) M. Schweiger, et al. 2017, “Understanding the energy yield of photovoltaic modules in different climates by linear performance loss analysis”, IET Renew. Power Gen. [DOI:10.1049/iet-rpg.2016.0682].

(16) M. Schweiger, et al. 2017, “Performance stability of photovoltaic modules in different climates, Progress in Photovoltaics: Res. Appl. [manuscript under review, DOI: 10.1002/pip.2904].

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choosing the optimal technology for hot climates to ... · chennai india 01 feb 2014 aw (tropical...

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