Practical notes on the route divisions: which routes are connect and notify, which apply first, and how the SGI-2 and SGI-3 fast-track lanes work.
G98 and G99 SGI-1 routes are connect and notify. If information in your notification is not correct, the DNO will ask you to correct it, so it is important to respond and not disregard it. There is also a risk that if you notified a job when an application was required, the DNO will demand an immediate disconnection of the system until the proper application is made and they approve it.
So even if you think a job is G98, the rules can be somewhat complex, and various things can make it require an application first. In CLRD you are only charged a job credit on the first pack generation of a job, just before submission; creating a job itself is free and unlimited. We therefore always and strongly advise creating the job in CLRD early, so you can accurately determine the actual route, and whether the DNO would allow it at all (phase imbalance restrictions, etc.).
The ENA and the DNOs regard G99 Type A as the normal application for jobs up to 50 kW, and the Standard Application Form (SAF) as the normal application above 50 kW. SGI-2 and SGI-3 are two fast-track lanes for applying with certain smaller jobs.
The main distinction is that Type A and above need the DNO’s design and planning team to do a full design study first, while fast track forgoes the design study. That said, for some DNOs an SGI-3 job is big enough that they need a loop impedance test performed by the installer.
You can avoid the loop impedance test by filing as a Type A, or by limiting export to 3.68 kW (11.04 kW for a three-phase system). The limited job is usually still an SGI-3, but in the shape of a small job.
On every SSEN and UKPN SGI-3 job above these limits, CLRD now asks for the loop impedance test before the application is generated. Otherwise the DNO takes about 3 weeks only to tell you to provide the test or limit export to these levels, and approval then typically takes a further 7-10 days from when you give your choice and an amended application. CLRD also gives you a one-click option to limit export to 3.68 kW (11.04 kW three-phase) or to file as a Type A, so you don’t have to do the test.
Note that filing as a Type A can in theory take longer or incur a connection fee. In our experience, though, SSEN and UKPN approve Type A just as quickly as the SGI-3 fast track, and every job we have processed so far has been free (no connection fee).
Only NGED seems to charge a connection fee for Type A jobs (£183). Where possible, CLRD recommends limiting export and filing it as an SGI-3, which incidentally doesn’t need a loop impedance test at NGED.
There are a few other special cases, with 2 or 3 single-phase inverters on a three-phase supply, where CLRD will also recommend an export limit that turns an SGI-3 job into an SGI-2 job, to avoid the impedance test and potentially get a faster approval.