The Value of Durable Materials in Maximizing Your
Investment in Solar Energy
Jon Previtali, Director of Technology & Technical Services
PV Magazine Webinar, November 2017
For Discussion & General Information Purposes Only
Wells Fargo Renewable Energy & Environmental Finance (REEF)
 Established in 2006 to provide tax equity capital for the renewable energy industry.
 Today, the group has 28 professionals with decades of combined experience in renewable energy.
 Collaboration with Wells Fargo CleanTech Banking which offers traditional banking services & relationship management.
Cumulative Solar Projects Financed by Wells Fargo (MWDC)
1,200
1,000
800
600
400
200
0
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
Cumulative Wind Projects Financed by Wells Fargo (MWAC)
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
2006
2007
2008
2009
2010
For Discussion & General Information Purposes Only
2011
2012
2013
2014
2015
2
2016
Wells Fargo Renewable Energy & Environmental Finance (REEF)
8+GW portfolio comprised of 50+ Wind projects and 300+ Solar projects
3
0
2
0
0
2
0
0
3
0
0
24
1
2
0
0
1
0
5
0
2
0
2
0
1
0
5
2
0
1
4
15
5
5 171
0
0
1
0
0
0
0
1
0
0
0
0
0
0
3
5
4
1
6
0
0
0
0
0
4
0
0
50
0
0
17
1
0
0
0
5
0
9
1
0
1
2
PR
12
# Number of Wind Projects within State
# Number of Solar Utility Projects within State
# Number of Solar DG Projects within State
0
0
0
0 MW Total Renewable Capacity within State
0.1-50 MW Total Renewable Capacity within State
51-150 MW Total Renewable Capacity within State
151-300 MW Total Renewable Capacity within State
> 300 MW Total Renewable Capacity within State
For Discussion & General Information Purposes Only
0
3
0
3
0
2
1
Typical PV Project & Portfolio Technical Due Diligence
Mechanical Completion
20% Initial Funding
(partnerships only)
Project
Commitment
Substantial
Completion
Term Sheet
Final Funding
(partnerships)
Funding (leases)
IECRE Standards & WF Approved Advisors
Project
Developer,
EPC, Operator,
Asset Manager
Planning,
Engineering, Procurement
Solar module
manufacturer
Construction
Pre-production audit & remediation, production
oversight (20%), pre-shipment inspection, QMS
data review
Qualification Accelerated Lifetime
Tests (ALT) for each BOM (CSA
EXP 450, DNV GL PQP, proposed
UL method) 2
ALT/Durability tests of module batch
(each BOM/assembly line combo3)
per IEC61215
Independent
Engineer1
Performance
Testing &
Final
Commissioning
Module production
Module factory
auditor1
Module Test
Lab1
Dry
Commissioning
Phase 1 IE Report,
construction lender IE
report or equivalent
Degradation rate tests (if needed)
Phase II IE Report
(more focus on long-term performance)
Construction Monitoring/Site Visits
Sampling techniques and expert judgement based on record can be used to reduce cost
Ideally done in advance of module production, but could be done at start of production
3 Unless factory auditor confirms consistency between assembly lines
1
2
For Discussion & General Information Purposes Only
4
Operation &
Asset
Management
Decom
or
Recom
Example of PV Module Accelerated Lifetime Testing (ALT) Scope of Work
Standard or Source
Weeks:
Days at Lab:
Air Shipment
Sample prep, outdoor preconditioning (Clause 5 61215)
Visual, EL, IV, Flash Test, Wet Leakage (when required)
Module Qualification Tests (IEC and Extended Testing)
TC (Thermal Cycling)
DH (Damp Heat)
DML/TC50/HF30
PID (Potential Induced Degradation)
Statistical Module Batch Tests (each BOM/factory combo)
TC (Thermal Cycling)
DH (Damp Heat)
TC50/HF10 (Thermal Cycling/Humidity Freeze)
PID (Potential Induced Degradation)
DML (Dynamic Mechanical Load)
LID (Light Induced Degradation)
PAN file validation/creation (for PVSyst)
IAM (Incident Angle Modifier) loss validation
Bypass Diode Test
Degradation Rate Characterization Tests*
75°C/20%RH
85°C/20%RH
95°C/20%RH
Other tests**
Modules:
Hot Spot Test
Components:
UV Exposure of Junction Box
Bypass Diode and Junction Box Thermal Test
UV Exposure for Encapsulants
UV Exposure for Backsheets
UV Exposure for Cables and Connectors
Result checks/Reports
Test Module Count or
Component Sample
Count
1
2
7
3
14
4
21
x
x
x
5
28
6
35
7
42
8
49
9
56
10
63
11
70
12
77
13
84
14
91
15
98
x
x
x
x
x
x
x
200
500
500
1000
1500
2000
x
NREL Qualification Plus
NREL Qualification Plus
NREL Qualification Plus
NREL Qualification Plus
IEC 61215
IEC 61215
IEC 61215
IEC 61215
IEC 61215
IEC 61215
IEC 61853-1
IEC 61853-2
IEC 61215
NREL special for Wells Fargo
NREL special for Wells Fargo
NREL special for Wells Fargo
varies
x
192
200
30 (6 per test) for 95%
confidence level that
90% of modules will be
defect free
500
x
x
x
All of sample set
500
500
500
6 (1 with defect + 1
control with no defect
per test)
NREL Qualification Plus
NREL Qualification Plus
NREL Qualification Plus
NREL Qualification Plus
NREL Qualification Plus
5
5
5
12
3
1000
1000
1000
1500
1500
1500
2000
2000
2000
x
500
96
Initial
Check
*Initiated for each BOM/factory combo, but stopped if no fault found in IEC baseline
**Performed if there is a reason for concern, e.g. historical defect, known issue, significantly new component, material or design, etc.
For Discussion & General Information Purposes Only
2000
x
x
3 of existing sample set
5
1000
x
96
20 of existing sample set
NREL Qualification Plus/ASTM E2481-06
800
5
Check 1
Check 2
Check 3
Check 4
Check 5 IEC 61215
Report,
Stop deg
rate char
tests if no
fault
found
~4000 hours>>
~4000 hours>>
~4000 hours>>
Extended
Test
Report,
Degradati
on Rate
Character
ization (if
needed)
PV Module Degradation Rate Characterization Analysis Method
Used in new energy production estimate
that feeds project pro forma and
purchase price.
Specific fault
ID’d in IEC test
Degradation
Rate Test
Results
Arrhenius
equation
coefficients
Arrhenius
equation
model
custom fit
for fault
Additional
degradation
due to fault.
Baseline
degradation
assumption.
Degradation Rate
Characterization Tests
75°C/20%RH
85°C/20%RH
95°C/20%RH
Typical Met
Year (TMY)
data for project
location
Built upon work by Kent Whitfield and NREL’s Mike Kempe, Sarah Kurtz,
Dirk Jordan, and John Wohlgemuth.
For Discussion & General Information Purposes Only
6
NREL study
(“Photovoltaic
Degradation
Rates — An
Analytical
Review”,
Jordan, Kurtz).
New
degradation
assumption plus
error.
A few latent defects we’ve seen in ALT testing
Bypass diode failures
Diode failure at
TC400
2-diodes fail at
TC600
For Discussion & General Information Purposes Only
Outdoor failure signature
7
A few latent defects we’ve seen in ALT testing
Accelerated cell corrosion
For Discussion & General Information Purposes Only
8
A few latent defects we’ve seen in ALT testing
Junction box lid failures
2014 testing
2014 testing
2014 testing
RETC
RETC
RETC
RETC
2014 + RETC
RETC
RETC
Resulting corrosion after 3 years near coast
For Discussion & General Information Purposes Only
9
Thank you!
Jonathan.m.previtali@wellsfargo.com
(415) 947-1980