New CEI 0-21 and CEI 0-16: application times defined

New CEI 0-21 and CEI 0-16: application times defined

New CEI 0-21 and CEI 0-16: application times defined

Publication date: 23 April 2019

ARERA, the Regulatory Authority for Energy, with the resolution of April 16, number 149/2019/R/EEL, defined the times for the implementation of the new 2019 editions of the CEI 0-21 and 0-16 Standards have been adapted to implement the European regulation EU 2016/631, called Rfg (Requirement for Generators), and 2016/1388 (regulation DCC - Demand Connection Code).

The Rfg regulation becomes effective from April 27, 2019

The Rfg regulation becomes effective from April 27, 2019; however, the Authority, based of the requests of the operators in the sector and the need of enough time for the adaptation of the products, has approved a gradual transition to the application of the new CEI, considering the current version already ensure a good level compared to the "European requirements".

In summary, ARERA determined:

  • The CEI 0-21 and CEI 0-16 Standards - 2016 edition can be applied for new connections, in low and medium voltage, if activated until 21 December 2019 and for all plants classified as "existing" (in the definition of resolutions 592/2018/R/EEL and 82/2019/R/EEL);
  • The new CEI 0-21 and CEI 0-16 Standards - 2019 edition will be applicable in other cases;
  • For requests for connections prior to March 31, 2020, a manufacturer's declaration (pursuant to D.P.R. 445/00) certifying compliance with the Standards in the 2019 edition will be sufficient;
  • For connection requests from 1 April 2020, compliance with the CEI 2019 Standards must be certified by a declaration drawn up by the manufacturers based on test reports carried out at an accredited third-party laboratory.


The innovations that have been introduced by the Rfg and harmonized in the new CEI 0-16 and CEI 0-21 2019 Standards are briefly:

  • ability for power units to bear new levels of "voltage dips" and to keep operative even in the event of rapid and significant frequency variations (and drift over time);
  • introduction of additional requirements for power units with a rated power greater than 6 MW.


Unified rules in the Continent for the connection power grid

European legislators wanted to standardize the rules for the connection power grid on the Continent, with the following objectives:

  • ensure the security of the transmission system and the stability of the grid
  • simplify the electricity exchanges,
  • encourage the integration of renewable energies,
  • ensure transparent and equal management of installations throughout EU

ARERA’s resolution is available at the following link:

New CEI Standards can be downloaded from:

Solax Inverters

A careful analysis of the new standards does not require any hardware changes on current devices. As soon as the procedures for the new accreditations and the test procedures are completed, the compliance tests will be repeated in the accredited laboratories, with a new firmware that meets the following new requirements:

  1. New P (f) curve (power depending on frequency). The power limitation starts at 50.2 Hz instead of 50.3 Hz.
  2. Frequency-dependent limitation of active power for SdA. Normal behaviour between 49,8 Hz and 50,2 Hz and limitation outside this range according to the fixed curve
  3. New profiles for the Fault Ride Through profiles. Tolerability curves and reaction to network holes change
  4. Frequency operating range changed on the high limit; 50.2 Hz instead of 50.3 Hz

Furthermore, the requirements relating to the immunity test for fast frequency drift (2.5 Hz in 1 second) and the requirements on EPS (Emergency Power Supply) are already met.

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