Troubleshooting Bad Connectors and Isolation Faults in ......About series resistance in PV systems PV module string equivalent circuit 1. I LIGHTis the current generated by light on

Webinar presentation EmaZys ApS

Troubleshooting Bad Connectors and Isolation Faults in Photovoltaics

Webinar presentation EmaZys ApS Page 2

Your presenter

Founder of EmaZys Anders

Anders Rand AndersenFounder, Inventor & CEOPh.D / M.Sc. PhysicsInvolved in solar energy since 2008

• Z200 PV Analyzer• Sold in 28 countries• Made for troubleshooting PV


Webinar motivation

• Annual photovoltaic plant operations and maintenance (O&M) costs will grow to just over $9bn in 2024

• Global cumulative solar PV installations are expected to grow from 500GW in 2018 to 1243GW by 2024

• As asset owners and operators continue to invest in advanced analytics and O&M specific software, and move from more time-consuming methods of spreadsheet-based analytics, operational costs will be reduced and higher data quality achieved

• PV system insights and PV education is a limited resource that makes effective asset management a challenge (EmaZys)


Webinar motivation

• We must be able to identify, manage and mitigate risks in solar PV assets

• To do this, we must realize that PV systems are made of many components

• The light absorbing (PV) solar cells are just part of a long chain that must be strong from end-to-end

• Cables, connectors, mechanical structures, DC breakers, inverters, bypass diodes etc. make up the whole system

• All though the solar cells are the actual energy transformation units, all components have the potential to severely delay and reduce the Return On Investment


Webinar motivation


Webinar motivation

Electrical arcing is a severe fault thats lead to fire

Root cases of electrical arcing

§ Moisture ingress degrading connections in connectors, junction boxes and switches

§ Incorrectly crimped connector contacts

§ The mating of incompatible plugs and sockets

§ Plugs and sockets not fully engaged

§ Loose screw terminals within junction boxes or isolator switches

§ Poorly soldered joints within a PV module junction box or other junction box defect

§ Damage to a component (e.g. broken busbar within a PV module).

§ The above leads to exposed conductors = > Riso faults and DC arcs


Webinar motivation


Webinar motivation


Webinar motivation

§ Investigation of module performance is just one key activity

§ Connectors make or break solar PV system economy

§ Faulty connectors can either impede (break) or redirect the flow of energy


Webinar motivation - take home message

PV finance tend to focus on module performance Connectors can be equally essential for investments


PV connector issues and typical faults - example

Severe PV faults include Electrical Arcing – what is arcing?

• Electrical arcing is the flow of electrical energy through air gaps

• Ionised air molecules turns into hot plasma (the arc)

• The plasma temperature depends on the DC current flow

• The plasma is very hot and initiate the combustion of surrounding PV materials


PV connector issues and typical faults

Electrical arcing – demonstration - https://www.youtube.com/watch?v=S9a2oPCIMr0

https://www.youtube.com/watch?v=S9a2oPCIMr0


Solar panel installations and components


Solar panel installations and components


Images of faults that caused Riso - leakage currents

Take home message:

• Damages to wires and conductors can lead to a leakage current and energy loss• Fire risk is seen when a leakage current evolve into arcs• Avoid or find ground faults

Forensic investigation


+ -

How can we measure solar panel fire risks? (on the DC side)

Riso fault, ground fault

DC current


How can we measure solar panel fire risks? (on the DC side)

Series resistance in the PV string - Joule heating

DC current

Leakage current

+ -


About series resistance in PV systems

PV module string equivalent circuit

1. ILIGHT is the current generated by light on the modules2. ID is the diode current3. Cd is the diffusion capacitance4. RP is the parallel (shunting) resistance5. RS is the series resistance

Bad connectors typically show up as raised levels of series resistance (or Riso problems)



How to meassure series resistance i.e. how to isolate the series resistance component

Ohm Law: U = R x I => R = U / I

Complex impedance:Z = R + j∙X

Practical measurements of complex impedance:Z = VAC / IAC

In words:Impedance is measured by superimposing a harmonic voltage on the PV system while measuring the harmonic current



How to meassure series resistance

Practical measurements of complex impedance:

Z = VAC / IAC = R + jX


Z = RS

Z = R + j∙X (inductance)

Note:Newest version of Z200 PV Analyzerwill calculate ideal values of Voc, Isc and Rs


Let us calculate the maximum allowed RS for a PV string

RS should be estimated in the frequency range f = 100 Hz to f = 10 kHz where the simple model is most accurate



Example:

STC string current = 10 A

STC string voltage = 500 V

Irradiation during test: 100 W/sq. Meter (only 10% of full daylight)

Extraction of the series resistance component - calculation


PV Field test methods and equipment

§ IV curve tracers

§ Simple array testers

§ Current clamps / voltmeters

§ Voltage pulse (Megger)

§ Infra-Red image recording

§ UAV

§ Energy production monitoring

§ Not many solutions dedicated to connectors/cable troublehooting

Many products avaialble


Trou

bles

hoot

ing

func

tions

Equipment Cost

Test equipment vs. O&M applications


PV troubleshooting test equipment market

Product comparison

Focus: troubleshooting and diagnostics. EmaZys Z200 PV Analyzer SOKODES 10P1 Seaward PV 150 PV Engineering

PVPM1000XFLIR T440bx IR

Camera

FLIR 75604-1404, Aerial

Thermal Camera (Drone)

GreateyesLumiSolar

outdoor EL test

Position of GND fault test ü û û û û û û

Position of disconnection test ü ü û û ü û ü

Open Bypass Diodes ü û û û ü ü ü

Shorted bypass diodes test ü û û û ü ü ü

Max voltage and current test ü û ü ü û û û

IV curve test û* û û ü û û û

Shunting indication (PID) test ü û û û ü ü ü

Tone generator and tone tracer pickup test ü û û û û û û

Prolonged fault monitoring & timer ü û û û û û û

Handy and mobile product ü ü ü ü ü û û

Operated by 1 person ü ü ü ü ü ü û

Mobile /web integration ü û û û û û û

Works in cloudy weather ü ü û û û û (only on dry nights)

Education and training required Medium Medium Low Medium/High Medium/High High High

End user price in EUR 6600 6.133 1.414 6.850 11.588 14.850 ≈ 30.000https://emazys.com/contact


Advantages of the Z200 PV Analyzer

• Superior "PV isolation" test and fault location methods built-in

• All std. PV tests included

• Tone Generator & AMP probe

• Locate bad connectors

• PID detection test mode

• Bypass diode functionality

• Easy control from smartphone or computer

• Export testing data as PDF, CSV og JSON format

• Designed to locate PV circuit faults

• Reduces fault finding work time in the field of photovoltaics

• Payback < 12 months

• Return On Investment > 45 % per year

• Emazys.com


Conclusions

1. The solar PV service market is growing fast for the years to come

2. Assets are not ”digital” yet, and field competence is in strong demand

3. Research clearly points at PV connectors as a main issue for system reliability

4. Connector and cable troubleshooting is difficult

5. EmaZys has focused on making equipment for PV troubleshooting


Q&A

https://emazys.com

https://emazys.com/


Documents

Troubleshooting Bad Connectors and Isolation Faults in ......About series resistance in PV systems PV module string equivalent circuit 1. I LIGHTis the current generated by light on