Technical failures - You can not manage the unknown

Stäubli AG - AE-Technical-failures-fwi-2x-69662-jpg-orig.jpg

The guiding principle for bankability is to minimize risk while to maximize the return. This can only be achieved through secured efficiency in the long term on the basis of high-quality components. Wrong choices in planning, due to lack of knowledge or low-quality components, can cause unexpected loss of production or potential safety issue during the lifecycle of a PV system.

The EU-funded Solar Bankability Project aims to establish a common practice for professional risk assessment on the basis of existing studies and collected statistical data of failures in PV plants. Its risk analysis tends to assess the economic impact of technical risks and how this can influence various business models and the LCOE.
In a first attempt, the project presents a cost-based Failure Modes and Effects Analysis (FMEA) to be implemented into the PV sector. It tries to define a methodology for the estimation of economic losses due to planning failures, system downtime and substitution or repair of components with respect to their impact on electrical and financial performance.

To provide a framework for the calculation of the economic impact, a special coefficient called CPN (cost priority number) has been introduced. It corresponds to RPN (risk priority number) in the classic FMEA and is part of a cost-based approach that has been applied to the collected failure data in order to prioritize the risks and their economic impact by means of the CPN ranking. The failure data are based on owner provided failure tickets and detected failures during on-site inspections. Several parameters were considered (e.g. plant type, costs due to downtime/fixing, plants affected by a specific failure etc.).

The economic impact of a specific failure can be split into two categories:

  • Economic impact due to downtime and/or power loss (kWh to Euros)
  • Economic impact due to repair/substitution costs (Euros) 

All factors which unfavorably influence the operation of the plant have a negative impact on the bankability of the PV project. As seen, the cabling and connectors can play a major role in this context as it has to ensure stable transmission of the generated power from the modules to the inverter or the consumption.