It is a well-known fact that modules interfere negatively with each other in a serial connection; while the modules’ peak operating points are diverse, traditional inverters use a ‘one-size-fits-all’ approach to harvest their energy. Partial shading, or uneven exposure to sunlight, diversifies the modules even further as some can produce more than others now.

1. Field Results of Energy Maximizing
Distributed DC Topology –
Residential & Commercial Installations
John Berdner, SolarEdge
General Manager for North America
8. September, 2010
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2. Energy Loss Factors in Traditional PV Systems
System Energy Loss
Design Energy Loss
 Module mismatch
 Limited roof utilization due
to design constraints
 Partial shading
 Undervoltage/Overvoltage
Indirect Energy Loss
 Dynamic weather MPPT loss
 No module level monitoring
©2010 SolarEdge
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3. SolarEdge System Overview
 Module level monitoring
 Module level optimization
 Fixed voltage - ideal installation  Enhanced safety solution
Power Optimizer
Inverter
Monitoring Server
Internet
©2011 SolarEdge
Monitoring Portal
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4. SolarEdge Distributed Technology
 ASIC-based Power Optimizers achieve:
 Per-module Maximum Power Point Tracking (MPPT)
 Efficiency: 98.8% EU weighted (99.5% peak)
 Conversion modes: buck, boost and buck/boost
 Wide module compatibility: 5v-125v, up to 400w
 Power Line Communication transceiver
 Module shut-down unless connected to an operating inverter
350W Thin Film
Module Add-on
250/300/400W
Module Add-on
©2010 SolarEdge
250/350W Module
Embedded
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5. Fixed String Voltage - Enabler
String voltage is always fixed, regardless of temperature
and string length
 Flexible design for increased roof utilization:
⁻ Parallel strings of unequal lengths
⁻ Modules on multiple roof facets
⁻ Modules with different power ratings
⁻ Modules of different technologies
 Longer strings lead to savings on wiring and BoS components
String voltage is always optimal for DC/AC conversion
 High inversion efficiency: VDC ≝ VAC·√2+ε
 Prevention of under/over voltage situations
 Inverter cost reduction
©2010 SolarEdge
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6. Field Trials and Results
©2010 SolarEdge
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7. Roof Utilization Case Study – Israel
 Optimal roof space utilization enabled a 15kW residential installation
 Four facets covered
 Unmatched modules in each string were necessary:
 Different module sizes (and rating)
 Different tilt and azimuth
 25 Suntech 280W modules
 34 Suntech 210W modules
 4 Suntech 185W modules
 One power optimzier per
module
 3 SolarEdge SE5000 inverters
 1 string per inverter:
20, 20, 23 modules
©2010 SolarEdge
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8. Roof Utilization Case Study – Results


Module-level monitoring reveals:
 No mismatch losses (module-level MPPT)
 No string mismatch losses (length agnostic fixed string voltage)
Attractive 5.1 kWh/kWp per day during August (compared to 5.5 for South-only sites)
280w
West
210w
West
280w
East
210w
East
280w
East
210w
East
©2010 SolarEdge
280w
West
210w
West
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9. Comparative Energy Case Study Methodology
 Side by side energy comparisons under similar conditions:
 Standard inverter compared to distributed system
 Both systems subjected to:
 Identical total DC capacity (otherwise comparing kWh/kWp)
 Identical module tilt and orientation
 Identical irradiance and temperature conditions
 Identical shading scenarios
Traditional system
©2010 SolarEdge
Power
Optimizer
Power
Optimizer
Power
Optimizer
Power
Optimizer
Distributed system
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10. Comparative Case Study 1 - Italy
 Power optimizers + SE5000 compared to four traditional inverters of
various brands (5kW, 5kW, 3kW, 6kW)
 Comparison without shading, and with simulated shading.
 Experiments done by Albatech, a MetaSystem Group company, an Italian
MW-scale turn-key integrator, and a technology oriented PV distributor.
©2010 SolarEdge
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11. Comparative Case Study 1 – Unshaded
 Under unshaded conditions distributed system produced
2.3% - 6.4% more energy than the traditional inverters
Energy Production 06-15 July 2010
60.00
kWh
40.00
30.00
20.00
10.00
Power Optimizers
+ SE5000
50.00
0.00
©2010 SolarEdge
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12. Comparative Case Study 1 – Shaded
 A cardboard panel was used to simulate a chimney-like sliding
shadow on 1-2 modules in each string with a distributed system
and inverter A
 The best performing inverter of three other un-shaded traditional
inverters was used as a reference
SolarEdge
Distributed
System
Inverter A
©2010 SolarEdge
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13. Comparative Case Study 1 – Shaded (Cont.)
 In reference to the unshaded inverter:
The distributed system recovered more than 50% of the energy
lost by traditional inverter A due to shading (-4% vs. to -8.63%)
Shaded
Unshaded
6.00
5.00
5.43
5.65
5.21
5.20
5.27
3.00
2.00
1.00
0.00
Power Optimizers
+ SE5000
kWh
4.00
©2010 SolarEdge
* Inverter B was disconnected due to a technical issue during this test
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14. Comparative Case Study 2 – Czech Republic





Power optimizers + SE5000 compared to 5kW inverter of a leading brand
Each inverter connected to 2 strings x 12 AWS modules x 185w = 4.4kWp
Three partly shaded modules in each string of each system
A third system remains unshaded for reference
Test performed by American Way Solar, one of CZ largest PV distributors
Unshaded
reference
Shaded
SE5000
Shaded
traditional
©2010 SolarEdge
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15. Comparative Case Study 2 – Results
 The distributed system produced 30.3% more energy than the
traditional inverter (58.96 kWh vs. 45.25 kWh)
 In reference to the unshaded inverter, the distributed system
recovered 77% of the energy lost by the traditional inverter due to
shading (6.5% loss vs. 28.3% loss)
14
Shaded
Daily energy, kWh
12
70
60
10
Shaded
Unshaded
63.12
58.96
Total energy, kWh
50
8
45.25
40
6
30
4
20
2
10
0
0
1
Power Optimizers + SE5000
Traditional Inverter
©2010 SolarEdge
2
3
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16. Comparative Case Study 3 - Germany
 Power optimizers + SE5000 compared to traditional 5kW inverter
with multiple MPP trackers
 2 string x 12 and 13 Solon P210 modules x 210w = 5.25kWp
 A section inside a large scale PV field
 No shading
©2010 SolarEdge
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17. Comparative Case Study 3 - Results
 The distributed system produced 1.65% more energy than the traditional
inverter
 On days with dynamic weather conditions, distributed module-level MPPT
recovers energy otherwise lost due to delayed MPPT process
Power
Power Optimizers + SE5000
Module-level MPPT energy
gain on that day: +2.9%
Traditional Inverter
©2010 SolarEdge
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18. The Impact of Dynamic Weather Conditions
 As shown in comparative case study 3, moving clouds induce rapid
fluctuations in irradiance level
 Centralized inverters are
Sep 2nd 2010
more limited in their ability
to track changes in Imp
as fast as they occur,
compared to module-level
MPP trackers
10:00 – 11:00
±3kW fluctuations exhibited
for a 5kW inverter in the
span of minutes
©2010 SolarEdge
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19. Comparative Case Study 4 – Germany
 Power optimizers + SE5000 compared to traditional 5kw inverter
with several MPP trackers
 2 strings x 9 Trina TSM220 modules x 220w = 3.96kWp
 Artificial shading simulating commercial layout inter-row shading
covers 0.5% of the PV array
©2010 SolarEdge
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20. Comparative Case Study 4 – Results
 The distributed system produced 4% - 8% more energy than the
traditional inverter on most days of the month
 Distributed system production was lower on days with very low
irradiance, due to sizable self consumption of the prototype DSP
version of the unit, now replaced by an efficient ASIC
Introduction
SolarEdge Daily Energy gain
vs. traditional inverter [%]
©2010 SolarEdge
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21. Comparative Case Study 5 – Spain
Layout
 Power optimizers + SE5000 compared to traditional inverter of a
leading brand
 2 strings x 7 BP 3200N modules x 200w = 2.8kWp
Shading
 Shade from a nearby
electricity cable
 Typical of residential
sites
 Module-level
monitoring revealed
shading pattern
©2010 SolarEdge
©2010 SolarEdge
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22. Comparative Case Study 5 – Results
Accumulated Energy comparisons shows the distributed system
consistently produces 4% more energy than the traditional inverter
Traditional [kWh]
Energy Gain in [%]

©2010 SolarEdge
SolarEdge [kWh]
Weekly Energy
Gain [%]
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23. Comparative Case Study 6 - Spain
Inverters
 Power optimziers + SE6000 compared to two traditional 3kw inverters
 4 strings x 10 Isofoton IS-150P modules x 150w = 6 kWp
Shading
 Inter-row shading
 Typical of commercial roof
with dense installations
 Modules are shaded for
2-3 hours every morning
Inter-row
shading
©2010 SolarEdge
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24. Comparative Case Study 6 - Results
 The distributed system produced 4.5% more energy on average
than the traditional inverter.
 On sunny days the
distributed system produced
up to 14% more energy due
to intensified partial shading
 On very cloudy days the
distributed system produced
2% – 3% more energy.
Clouds and low irradiance
cast diffuse light with little
or no partial shading.
©2010 SolarEdge
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25. Questions
what where
how
when why
Questions!
what where
how
when why
who
who
©2010 SolarEdge
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26. Thank you
John Berdner, General Manager North America
Email: John.berdner@solaredge.com
Twitter: www.twitter.com/SolarEdgePV
Blog:
www.solaredge.com/blog
©2010 SolarEdge
Website:
www.solaredge.com
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