1. Fleet Data:
Key Topics and Conclusions
Dr. Tassos Golnas / July 15, 2015
Intersolar NA 2015

2. P. 2© 2015 SunEdison, Inc.
Dataset description – Work Orders
 ~9,000 work orders
• …for ~900 PV power plants
̶ …with total capacity of ~2.5 GWp
̶ …located in 33 states, provinces, or countries
• …issued between 2014-01-01 and 2015-03-31
 Variables examined:
• Power plant ID
• Location
• Estimated energy impact of incident
• Duration of incident
• Work order type
• Failure area

3. P. 3© 2015 SunEdison, Inc.
Energy impact, frequency, and duration per WO type
46%
16%
14%
11%
4%
3%
6%
-10%
0%
10%
20%
30%
40%
50%
60%
0.01 0.1 1 10 100
Fractionofincidents
Median duration (days)
Inverters
Grid
AC
subsys
Host
Other
Trackers
DC Subsys

4. P. 4© 2015 SunEdison, Inc.
High impact, high frequency: Inverter outages
46%
-10%
0%
10%
20%
30%
40%
50%
60%
0.01 0.1 1 10 100
Fractionofincidents
Median duration (days)
Inverters

5. P. 5© 2015 SunEdison, Inc.
Medium impact, low-to-medium frequency
16%
14%
11%
-10%
0%
10%
20%
30%
40%
50%
60%
0.01 0.1 1 10 100
Fractionofincidents
Median duration (days)
Grid
AC
subsys
Host

6. P. 6© 2015 SunEdison, Inc.
Low impact, low frequency
4%
3%
6%
-10%
0%
10%
20%
30%
40%
50%
60%
0.01 0.1 1 10 100
Fractionofincidents
Median duration (days)
Other
Trackers
DC Subsys

7. P. 7© 2015 SunEdison, Inc.
Medium impact, low frequency, long duration: Inverter wty claims
30%
16%
-10%
0%
10%
20%
30%
40%
50%
60%
0.01 0.1 1 10 100
Fractionofincidents
Non-wty
issues
Wty.
issues

8. P. 8© 2015 SunEdison, Inc.
Inverter incidents: “20/80” rule for impact and duration
0%
20%
40%
60%
80%
100%
0% 20% 40% 60% 80% 100%
Cumulativefraction
Cumulative fraction of incidents
Energy impact
Incident duration
Note: Incident duration and Energy impact values are sorted
in descending order independently of each other

9. P. 9© 2015 SunEdison, Inc.
Grid stability and grid outage duration
0
6
12
18
24
0
100
200
300
400
500
600
700
800
TH IN IT TX ON MY W-US GB PR E-US SP
Mediandurationofincident(hours)
Incidentsxaffectedfractionoffleet

10. P. 10© 2015 SunEdison, Inc.
Dataset description – Long-term Estimates
 417 PV plants built in NAMR between 2007 and 2011
• 180 built in US Northeast and Ontario (largely DG rooftops)
 Performance Index (PI) =
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷
𝑃𝑃𝑃𝑃𝑃𝑃𝑓𝑓𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 (𝑝𝑝𝑝𝑝) 𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸
 Lifetime PI: Index calculated over the lifetime of the plant
 Estimates generated by Engineering firms hired by project
investors

11. P. 11© 2015 SunEdison, Inc.
Lifetime Performance: Estimates and Reality
<80%
80-85%
85-90%
90-95%
95-100%
100-105%
105-110%
110-115%
115-120%
>120%
2007 2008 2009 2010 2011
LifetimePerformanceIndex

12. P. 12© 2015 SunEdison, Inc.
Long-term estimates underestimate snow impact
Vintage 2007 2008 2009 2010 2011
Projects exceeding
estimates during winter
months
6% 0% 3% 0% 5%
Projects exceeding
estimates during non-winter
months
71% 93% 76% 71% 64%
 Only plants built in the Northeast US and in Ontario are
considered in this table
 Both performance indices calculated over the lifetime of the
plants

13. P. 13© 2015 SunEdison, Inc.
Conclusions
 Inverter outages account for almost 50%
• …of the recorded incidents and
• …of the total estimated energy impact
 A small minority of inverter issues are warranty related but
have outsized impact due to lengthy resolution times
 Inverter and downstream outages account for ~90% of the lost
opportunity for generating energy
• ...with ~30% from causes unrelated to PV equipment
 A minority of events has an outsized energy impact
• …and/or requires a very lengthy resolution

14. P. 14© 2015 SunEdison, Inc.
Conclusions - Continued
 Weak grid in certain APAC countries causes many short-
duration system outages
 Accuracy of long-term performance estimates increases with
experience
 However, calculation of snow impact on rooftops is still
inaccurate
• Extreme interannual variability of snowfall can also impact results
in the near-to-mid term

15. P. 15© 2015 SunEdison, Inc.
Acknowledgements
 SunEdison ROC and field staff
 Nikhil Garg
 TJ Keating
Thank you!
tgolnas@sunedison.com