Suntech Engineer Visits RCS Solar Customers in Israel

7/31/2019 Suntech Engineer Visits RCS Solar Customers in Israel

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ISRAEL Energy AuditAndreas Iliou - measurements analysis, connectors


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01Module Circuit Design

Different strings

Iso fault measurements


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Powador Inverters modules STP 210 18 Ud

It is highly important to measure one module only against frame , either isolatedwith wood or similar isolator


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Measuring + Pole and Pole seperate against frame or/ and structure


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01

Earthing structure several times earthed towards the roof structure , thereforeIf the wiring to bond with the earth near inverter is not big enough ,after

Kirchhoff s law, current will flow according the lowest resistance.


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7 Module Circuit Design Analysing

Measured 25,9 MOhm with normal Isolationtester Megger ~okIf still mounted on the structure


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8 Module Circuit Design Analysing

Measured (isolated) real values / 1 module but + and - shortcut


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9 Module Circuit Design Isolation fault

Measured 625 MOhm with Isolationtester HT 420


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10 Module Circuit Design Analysing/ImpedanceImpedance

The current will flow in any direction, if earth wire (back) is to small

UL = 25V0.71 Ohm (RS)

338 Ik

UL = 25V1.04 Ohm (RS)

230 Ik

UL = 25V0.18 Ohm (RS)

1315 Ik

230V +50A*0,71Ohm~265,5V AC

230V + 50A*1,04Ohm~282 V AC

230V + 50A*0,18Ohm~239 V AC

Overcoming earthing (Ri)and Impedance (Rn)problems-

-with a existing value of 1,02 OhmRn~ max 10,791 kW 3 phase can be realised


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01

Earthing with Aluminium corrosion protected

Different clamp variations


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01

Earthing with Aluminium corrosion protected

Lightning rods can be used to bond , without corrosion- like sample here


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14 Modules checked , earthing concept

Value to high 13, 79 Ohm measured, flow will divert into the Pillars


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15 Modules checked , earthin concept

Value to high 4,8 Ohm measured, flow will divert into the Pillars


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16 Modules checked , earthing concept

Value here 0,08 Ohm measured, flow will divert into the Pillars-The other earthing point not good


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17 Module 816W/m 25degrees angle

1. Row 2,4A ~ 7A

816 W 46,4 degree C

Cloudy but values ok

2 rows always checked with temperatures 44 degree C


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18 Bypass Diodes

Bypass diodes getting hotter, heating up- normal values


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19 Conclusion

-During dry period all measurements done showed > 199 Ohm

-When we poured water over the surface and tested with PV Benningvalues stayed longer on safe side

because of it s triggering capacity and adjustment regards PV

Megger testing device not purely for PV onlyEarth loop and Neutral Impedance has to be checked on site

- Earth Rod has to be done via Tri Pod or 45 degrees angled( wrong/false readings from Inverter )

During operationthe module somehow accumulated static loads.

With a massive grounding ( way below 1 Ohm) we can dischargequickly any static or impedance driven faulty readingsand

faulty Phantom Iso fault will disappear.The inverter if configured upfront Suisse Mode by that a emf friendly version


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20 Conclusion I

Equal to the new israely local requirements ( since 2012 )Earth wiring should be done via a aluminium wire only,

- The earthing structure won t corrode over time otherwisewe will face the same problem every year once the earth will

loose it s conductivity over time.- 10sqmm or 16sqmm are sometimes not enough it should be strong enough

to bring any problems ( leakage currents) back to source withoutstray currents involved direct or indirect.

- The surface of the installed m should not exceed 60. Afterwards the structure should be broken to let not to many modules ran parallel over the same area


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21Thank you Andreas Iliou

Suntech Engineer Visits RCS Solar Customers in Israel

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