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Mismatch,Shade,tools recommended during energy audits- PV systems
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Inspection
Why including measurements?
Visual inspections is not enough!
Andreas Iliou - shading and measurements analysis
1 Module Circuit Design
2 Mismatch Effects
3 Hot-Spot Heating
4 Bypass diode, temperature
01Module Circuit Design
19 modules per string
4 Module Circuit Design – Shading
Some strings are shaded , flowers / Pylones
5 Module Circuit Design – Shading
Some strings are shaded , flowers / Pylones
6 Module Circuit Design – Shading
Some strings are shaded , flowers / Pylones
7Modules shaded via transmissionlines
PV Plant with similar shadings from a Transmission line
8 Module Circuit Design -Shading
Modules performance less in substrings shadedduring the whole day
Could be regrouped easily as place is available
shadingshade
Soft shade
9 Module Circuit Design -Shading
„Noise “measured on site during Shading e.g M9 O1 U3.2 G8 2,38 Ohm / 245 mA AC leakage current !!!
Rows shaded
shaded
10Module Circuit Installation
1 module was dismantled from the wind, therefore shading another 5 modules in different strings – future hotspot possible !!
11Module Circuit Installation
Mountain/ Valley installation so different values as module strings have different angles towards the sun
02Mismatch Effects
13 Mismatch Effects
M9.O1 U3.2 C36 –G8
6,8 A 13,3 mA7,4 A 14,7mA
6,5 A 15,9 mA7,6 A 14,8mA7,1 A 13,6mA
7,0 A 13,5 mA
AC leakage current
M9.O1 U3.2 –G82,38 Ohm / 245 mA
at earthing point
Different angles towards the sunSee more details sep. excel sheets
14 Mismatch- what can be achieved with measurements on site ?
A 1 / G 10
0,3mA 7,2 7,7 7,6 6,9 7,1 7,6 A1
2Ohm /3,8mA
44,7
44,3
44,2
45,4
44,2
51,6 G10
Shaded row , or burned busbars will show deviations
Shaded array
Here 51,6 A instead normally 44,7 – 45 A
Due to contact problems increasing resistance
15 Mismatch Effects
See more details sep. excel sheets
Instead of normal values 44- 45 A
this substring is over the limit
After investigation it shows
Burned current sensors
We need to do Visual andMeasurements on sites
One alone is not enough
03Hot-Spot Heating
17Field Observation
This results have been caused by the shading permanently of some
substrings via transmission lines/ or –and Pylons
Hotspots are not accumulated right now- future ?!
Siemens Les Mees
( see page 7)
04Bypass Diodes
19 Bypass Diodes
Normal picture with bypassdiodes getting cooled
20 Bypass Diodes
Bypass diodes getting hotter, heating up -> shading