Stefan Winter, PTB German member of IEC TC82-WG2
12.10.2016
Standards for PV metrology IEC 60904 and IEC 61853
Overview
o Demand for high accuracy solar cell calibrations
o Standard Test Conditions
o DSR Method
o The new PTB setup: Advantages and disadvantages
o International Comparisons => WPVS
Magnitude of Solar Energy
• Sun radiation onto earth corresponds to 120,000 TW • Total human energy need today: 13 TW
Solar energy is the only kind of energy that can solve the earth‘s energy problems!
Sources: G.W. Crabtree and N.S. Lewis, Physics Today, March 2007 ; and Prof. Eicke Weber, ISE
Land requirements for PV
Source: G.W. Crabtree and N.S. Lewis, Physics Today, March 2007 sowie Prof. Eicke Weber, ISE
You need 6 areas of 340x340 km² (1800 kW/J) with actual available solar modules (15 % eff.) to get 20 TW
Energetic amortization of PV systems
• Study for the German Federal Ministry of Economics, Technology and Labor:
• Including solar modules, mounting system, frames, cabels, inverter, auxiliary energy, operating supplies
• Briem et al, Study „Lebenszyklusanalysen ausgewählter zukünftiger Stromerzeugungstechniken“ made by Institut für Energiewirtschaft und Rationelle Energieanwendung an der Universität Stuttgart, Deutsches Zentrum für Luft- und Raumfahrt, Institut für Technische Thermodynamik, Stuttgart, Forschungsstelle für Energiewirtschaft e. V., München and the „Lehrstuhl für Energiesysteme und Energiewirtschaft“
• Published by the VDI-Verlag in 2004 (Page 133, Tab. 7-15)
Energetic Amortisation time in years
sc-Si system 2,2 pc-Si system 2,3 a-Si system 3,2 CIS System 2,1
Future trends
Economic Impact of Measurement Uncertainty for Photovoltaics
Source of data: EPIA (European Photovoltaic Industry Association) and for 2015 according to IHS market research institute
• Financial uncertainty = Global annual installation × Price × Uncertainty • 2012: Financial uncertainty = 30 GW/year × 1.7 €/W × 1 % = 500 M€/year
⇒ A measurement uncertainty of 1% leads to a financial uncertainty of 500 M€/year ⇒ High demand for high accuracy solar cell calibrations
Solar parks are financed from banks, who add the financial uncertainty arising from measurement uncertainty to the total amount to be financed. A low uncertainty leads to competitive advantage.
Source of data: www.solarwirtschaft.de/preisindex
2006
2007
2008
2009
2010
2011
2012
0
1
2
3
4
5
Syst
em p
rices
for e
nd c
usto
mer
s in
Eur
o / W
att
Prices in Euro/Watt
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
*0
10
20
30
40
50
Year
ly wo
rldwi
de n
ewly
inst
alle
d PV
Pow
er /
GW
New PV installations
Metrological Integration
Calibration- laboratories
PV - Industry
Calibr.-Costs in Euro 3000 - 4800
Uncertainty (k=2) > 0,5 %
400 - 900 > 1,5 %
The pure measurement time for the calibration of one solar cell is about 24 hours.
IEC 60904-2
PV calibration chain
PV-Module
ΙSTC
STCΙ
0,1%
< 0,01%
0,5%
Cryogenicradiometer
Standard Detector
Reference solar cell
Laser Current and Voltage Measurement
DSR Facility
Source
Detector
Facility
Monochromatic + Bias radiation
IV-CharacteristicsSolar simulator
Legende:
λ, Ε
Φ, P
λ
Εs (λ),
Φs (λ)
Ε
Oerlikon
Standard Test Conditions
• Reference solar spectrum AM1,5
• Irradiance ESTC = 1000 W/m²
• Cell-Temperature (25°C)
• Angular distribution important, but not defined
The calibration procedure must take into account these STC according to IEC 60904-3.
EMRP Project PhotoClass
From Standard Test Condition to Climate Zones From Peak-Power to Energy rating
Definition of new Standards (IEC 61853 series) Task of PTB: • Metrological background • Building up measurement capabilities for new measurement tasks
Metrological background
,NormPhotocurrent: ( ) d( )E sI λ λλ λ= ⋅∫
Reference solar spectrum AM1.5 according to IEC 60904-3:2008
Spectral responsivity of different solar cells
200 400 600 800 1000 1200 1400 1600 1800Wavelength / nm
2468 135Photon energy / eV
0,0
0,2
0,4
0,6
0,8
Abso
lute
spec
tral r
espo
nsiv
ity, s
/ AW
-1
η = 100% c-Si
GaInAs
CdTePoly-Si
CIS
a-Si GaInP
Ge Component Cell
400 600 800 1000 1200Wavelength, λ / nm
0
500
1000
1500
2000
2500
Spec
tral i
rradi
ance
Eλ /
mW
m-2
nm
-1
AM1.5 (IEC 60904-3:2008)
Solar cell
Bias radiation E b
Modulated monochromatic radiation, measured with Ref.-PD
∆E(λ)
Ib + ∆Isc(λ, Eb)
DC-Multimeter + Lock-In-Amplifier
DSR-Method Differential Spectral Responsivity
0 20 40 60Time t
ms0
2
4
6
8
10
Irrad
iance
E
: Monochromatic + bias radiation: Bias radiation
IEC 60904-4
x,y,z-Table
Monochromator
Optics (Lenses, Apertures, Monitor phodiode)
Biasradiator
Φ-θ-Goniometer
Pulse-to-CW Convertor
(Fiber)
Chopper
Climate Chamber
Lasersystem (Ti:Saphir Laser, OPO, SHG, THG, FHG)
Electronic
Compact Array Spectroradiometer
Design of the new Laser-DSR Facility
Calibration objects Reference solar cells
200 400 600 800 1000 1200 1400 1600 1800Wavelength / nm
2468 135Photon energy / eV
0,0
0,2
0,4
0,6
0,8Ab
solu
te sp
ectra
l res
pons
ivity
, s /
AW-1
η = 100% c-Si
GaInAs
CdTePoly-Si
CIS
a-Si GaInP
Ge Component Cell
Component solar cells
Industry solar cells
Determination of the Electrical Power using IEC 60904-4
0 200 400 600Voltage V
mV
-150
-100
-50
0
50Cu
rrent
I / m
A
-40-20
0204060
Elec
trica
l Pow
er P
/ m
W
Energy-generation
Energy-consumption
Isc
VOV
0 200 400 600Voltage V
mV
-150
-100
-50
0
50Cu
rrent
I / m
A
-40-20
0204060
Elec
trica
l Pow
er P
/ m
W
Energy-generation
Energy-consumption
IMPP
VMPP
PMPP =Pelektrisch
Isc
VOV
Maximum-Power-Point
0 200 400 600Voltage V
mV
-150
-100
-50
0
50Cu
rrent
I / m
A
-40-20
0204060
Elec
trica
l Pow
er P
/ m
W
Energy-generation
Energy-consumption
IMPP
VMPP
PMPP =Pelektrisch
Isc
VOV
Maximum-Power-Point
IUP ⋅=
Realisation und maintainance of the „World Photovoltaic Scale“
NREL
PTB
TIPS
AIST
Conclusion and Outlook
o PV is a 50 billion/year market
o DSR method takes the IEC 60904-3 into account and is explained in IEC 60904-4
o PTB ensures the traceability of reference solar cells
o PTB has developed the next-generation of the DSR facility with world-wide lowest measurement uncertainty: LASER-DSR
o It is a multipurpose spectral comparison facility. s = s(λ, E, fChopper, T, x, y, z, ϕ, θ)
o One application: Energy rating
o Future development: Calibration of reference modules