Small components. Big impact.Cabling of PV installations – Key factors for a successful long-time reliability

Olivier E. Haldi, Global Business Development Alternative Energy, Headquarters Switzerland

Stäubli Group – three activities, four divisions

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> 125 years experience

> 270 GW PV connected

> 5500 employees in 29 countries

Formerly:

YOUR BANKABLE PARTNER

Cabling of PV system – You can’t manage the unknown

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PROJECT BANKABILITY

Lack of knowledge about eBOS components (cabling/ connectors) …

Component → technology, norms, materials, production processes

Installation → norms, tools, assembly instructions

… and/or their relevance for the long-term success of a PV system

Technical issues and their root cause

Consequences/ risk on efficiency (LCOE), profitability (ROI)

Resulting in: Cabling/ connector failures in PV systems

Failures and their financial impact

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PROJECT BANKABILITY – FIELD DATA

Solar Bankability project by European Commission’s Horizon 2020

Common practice for professional risk assessment to reduce risks for investments in PV projects

CPN (cost priority number) = cost-based failure mode and effects analysis(FMEA)

Method was applied to database of >1 million documented failure claims (empirical and statistical)

Technical failures/risks and their economic impact due downtime and/or power loss & repair/substitution costs

Indication of the economic risk (in average) of a specific technical risk

Cable & connector with huge financial impact → Euro/ kWp/ year loss due to the failure

Risk mitigation measures should be selected with an objective to minimize the LCOE by optimizing the balance between the CAPEX and OPEX

www.solarbankability.org

Why connectors can have this big impact

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PROJECT BANKABILITY – CONTACT RESISTANCE

Consequences:

Constant low contact resistance = Long-term reliability and efficiency

Component Quality – PV DC Connector

6

O-RingCap Nut Plug Insulator Cap NutSealing Socket Insulator Metal Part Plug SealingMetal Part Socket

PROJECT BANKABILITY

PV DC Connector

Socket(marked «+» / female)

Plug (marked «-» / male)

MULTILAM

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Component Quality – Stäubli Technology: MULTILAM

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PROJECT BANKABILITY

Scale

TMin = 25°C

TMax = 45°C

MC4 (MULTILAM Technology)

Measurements acc. to IEC60512-5-1

Competitor Product (no MUTLILAM)

Component Quality – Contact Resistance

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PROJECT BANKABILITY

Initial measurements and after TCT/DHT Stable low contact resistance

Contact resistance / cycle

0.0

100.0

200.0

300.0

400.0

0 2000 4000 6000 8000 10000

Number of cycles

Res

ista

nce

(m

icro

-Oh

m)

Crimp resistance / cycle

0

10

20

30

40

50

60

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Number of cycles

Res

ista

nce

(m

icro

-Oh

m)

10’000 cycles representing ~ 20 years!

OperationConstructionConception

Risks Sources - Impact on LCOE (Levelized Cost of Energy)

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PROJECT BANKABILITY – MAIN RISK SOURCES

+

Components

Installation

Financial and Safety Risk

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PROJECT BANKABILITY – FIELD DATA

Failure pattern

Broken/ burned connectors (cross-connection)

Consequences

Performance loss due to downtimes

Extra service/ repair cost

Original x Original Ø 1660,00 MΩ

Original x Original Ø 532 µΩ

Cross-Connection Ø 0,06 MΩ

Cross-Connection Ø 6841 µΩ

Norm value R > 400 MΩ

Initial value R Ø 530 µΩ

Contact Resistance

Site location: Europe

Size: 3000 strings

Operation: 5 years

Insulation Resistance