CPV Today - Defining the requirements of a technology which still is under development

Reliability and durability are two main parameters that guarantee operational behaviour, safety and profitability in any CPV system.

Reliability and durability are two main parameters that guarantee operational behaviour, safety and profitability in any CPV system.


Reliability can be defined as the probability of failure in the system. The parameters that measure reliability are the Mean Time between Failures (MTBF) and also the time needed to repair a certain failure. On the other hand, durability is described as the lifetime of a system. It can be understood as a point of time beyond which, maintaining the operation of the system is not profitable in economical and energy terms.

If CPV technologies are to compete against conventional PV, the levels of reliability and durability offered by CPV systems must be at least as high as the ones provided by conventional PV, according to CPVToday.

In its industry report, titled The CPV Challenge (Part I): Achieving Grid Parity, CPV Today has stated that it is difficult to gather information about reliability and durability experiences in CPV systems, as most of them are still in a prototype phase; so, the field experience is limited.

Those difficulties get worse because the companies involved in concentrating photovoltaics are reluctant to share their achievements and difficulties due to market strategies and research confidentiality.

Meeting a series of minimum requirements

The industry acknowledges that it is essential for large scale penetration of CPV installations to guarantee that concentrators meet a series of minimum requirements during the design stage and subsequent manufacturing.

"It is essential to establish standards which help customers easily understand the product and to help financial institutions assess the financial possibilities of CPV," said LPI's Juan C. Miñano, who is scheduled to speak during the 2nd Concentrated Photovoltaic Summit, to be held on 28-29 April in Toledo, Spain.

"At this time, these standards should focus on electricity production (and its cost) and the reliability of the system almost exclusively. No standard can be established as to the internal aspects of CPV technology because the technology is not sufficiently mature," added Miñano, a renowned non-imaging optical scientist.

Improvements for standardisation norms

CPVToday's report recommends that it is necessary to undertake improvements not only in the definitions of CPV standards that are under actual development, but also to suggest a number of possible changes in the IEC 62108 standard.

The most critical and urgent regulations that must be developed for the CPV industry are the following ones: Energy and power rating; Measurement standards; Spectral and temperature conditions standards; Safety standards; Tracker standards.

The industry needs to assess:

* What sort of control tests must be gathered in norms to speed up the market? How the tests have been modified to be adapted to the peculiarities of concentration technology?
* Possible improvements for standardisation norms - it is necessary to undertake improvements not only in the definitions of CPV standards that are under actual development, but also to suggest a number of possible changes in the IEC 62108 standard The most critical and urgent regulations that must be developed for the CPV industry are the following ones: Energy and power rating; Measurement standards; Spectral and temperature conditions standards; Safety standards; Tracker standards.
* Problem that most certification organisms are facing.
* Explanation and tests included in IEC 62108.
* The IEEE standard limits the sort of CPV systems included in the norm.





Significantly, the CPVToday report highlights that the inclusion of additional tests and the adaptation of some of them is a consequence of the so-much-emphasised big difference in the characteristics and behaviour between CPV and flat-plate PV.

"It is surprising that some of the tests of the flat-plate PV standard are not included in the CPV one. The main reason for that is the lack of CPV standards, which makes it impossible to define some tests for CPV modules or assemblies," says an extract from the report.

Points to be addressed

There are several points of the present IEC 62108 norm that should be taken under consideration in the next revision of the standard.

For instance, the present version of the standard only considers five different CPV technologies. Nowadays, a huge variety of concentrating PV systems are emerging and being tested.

As CPV industry is developing really fast, it would be a good idea to write an annex to the norm that specifies all the CPV systems that can be gathered under the denomination of concentration photovoltaics.

Also, the standard compiles a wide variety of CPV systems. According to their technical aspects, not all the systems have the same performance behaviour and some of the tests suggested could be excessively restrictive with some systems which do not require those levels.

It is obvious that if CPV is trying to compete against conventional photovoltaics, it should have, at least, the same requirements as conventional PV.

Nevertheless, the complexity of this new technology and the differences among all the CPV configurations will make the new requirements stricter than the ones defined for flat-plate PV.


About CPV Today

For more information on the 2nd Concentrated Photovoltaic Summit in Toledo, April 28-29, site visit to ISFOC on April the 30th and to check the full list of attendees, speakers and agenda please go to www.cpvtoday.com/eu09 or contact Belén Gallego by email on belen@cpvtoday.com

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