Some 4kWp Systems May Now Require Pre-Approval from DNO

4kWp solar systems now require permission

by Solar Selections on March 20, 2012

When connecting a solar power system to the grid, the application process involves submission of a form to the relevant Distribution Network Operator (DNO). With systems above a certain size DNO’s are now demanding certain forms be submitted prior to installation, which has not been the case previously. Which forms and when are two important matters covered in this article.

There has been some confusion in the industry of late regarding size limitations placed on domestic solar power installations. With Distribution Network Operators (DNO) claiming 4kWp solar systems to now be too large to be installed without prior consent, this issue is an important one. It is no longer possible in many regions to legally install a 4kWp system without first consulting the DNO.

Registering Solar Generators with the DNO – Does my system need pre-approval?

Different sized systems require different application forms be sent to the DNO. The general expectation is that the larger a system, the more pre-emptive documentation is required to be submitted to the DNO and approved prior to installation.

The main threshold for a solar power installation is whether it is above or below 16 amps per phase. Whether a 4kWp solar system puts out power above or below 16 amps will depend on the specifications of its inverter. Most inverters for such systems do not reach this threshold, and will not require DNO approval.

Small Scale Generator and the G83

Systems deemed to be fewer than 16 amps per phase are considered ‘small scale’. They can be installed straight away and registered by submitting a G83 form to the DNO after the installation. EON has a copy of their G83 form here for download.

Your installer will be able to advise you on the amp capacity of your system specifically, so be sure to ask them. Now seeing as the feed-in tariff changes only after 4kWp for PV systems; this presents a different approach needed for installations between 3.68kWp and 4kWp.

Large Generators and the G59

For generators over 16 amps per phase it is a legal requirement for the DNO to be consulted prior to an installation taking place. In addition, a G59 form (download here) is required to be submitted. The process of a DNO reviewing and returning a successful G59 can take up to 8 weeks.

Obviously the important aspect of this process is establishing the amp levels of the proposed solar power installation with the installer’s electrician. It is vital that anyone installing systems from 3.68kWp upwards establishes the correct process for registering their system. This is especially the case with the deadlines of April 1st and July 1st 2012 approaching, as in reality anyone considering installing a 3.68kWp to 4kWp system before the tariff drops in July should be comparing their options and beginning the process well before April 2012 is through.

Written by Jarrah Harburn

T: 020 7205 2267

© 2012 Solar Selections Ltd

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{ 1 comment… read it below or add one }

Ian Andrews September 25, 2012 at 3:23 pm

You do realise that the DNO limits relate to the total capacity of the inverter, ie what can be exported to the local grid?. Many inverter are limited to 16 Amps and so 4 kWp of panels can be connected without needing any permission from the DNO.


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