Grid Tied Inverter Installation.

Apparently the system is a 5kW one.

Single phase or 3-phase? Which side of 16A/phase makes a big difference…

   - Andy.

If it's a 5kW single-phase inverter, it needs DNO approval before installation.  The maximum for simple notification is 3.6kW (16A) per phase.  But you can stick more than 3.6kW of panels on a 3.6kW inverter, and just lose the excess generation on a sunny day.

If you're not MCS registered, then the owner won't be able to claim any payments for the electricity they generate.  That is, unless you're just doing the wiring and an MCS installer will be signing it all off.

Might be telling you the bleedin' obvious but inverter manufacturers' instructions normally do give a reasonable recommendation for MCB to account for any inrush; I would suggest B16 may be a little tight. Likewise you need to find the statement from them that DC leakage isn't an issue so type B RCDs aren't required (and you do need to check the upstream RCDs aren't AC)... Decent manufacturers will do this but customer-supplied could be anything and BS7671 requires you to check.

I presume I don't need to tell you that standard AC isolators often aren't rated for DC circuits on the PV array side of the inverter.

Who is responsible for commissioning? If you then there is a procedure for energising the inverter (even if type-tested... is it definitely pre-set to UK grid codes, for example, or does that need to be selected on first start?) Someone needs to test the DC side, which is normally done with specialist tools and an understanding of the specific hazards.

Who is notifying the DNO of commissioning, and, if it's G99 (5kW 1ph), is a connection agreement already in place?

Suggest a canter through EREC G98 (for <16A/ph) or EREC G99 (>16A) and the IET Code of Practice for PV. Also BS EN 62446 (and 62548 though that doesn't appear to be your scope) applies.

Irrespective I would suggest you have a duty of care towards the wider installation... Why are they calling you in for the inverter but doing the array themselves, if not to have some form of cover?

For less than 16A per phase, there is a legal requirement to notify the DNO within 28 days of its first connection to the grid, using the forms in standard EREC G98. The inverter must be type approved to EREC G98 and it’s installation comply with the standard. 

For a 5kW single phase inverter, there are additional legal requirements (and forms) and the inverter and installation must comply with EREC G99. The DNO must also be consulted before the first connection to the grid is made. 

EREC G98 is a 65 page read, and EREC G99 is a 366 page read. 

Regards,

Alan. 

link to ENA_EREC_G99

link to ENA EREC_G98

At least some documents are freely available.

Part of me wonders as the benefits of the registered installer subsidies fade, how many solar inverters and car chargers will just appear without notifications and paper trail, much as electric showers do now. One has to ask what is the benefit to the customer of jumping through the hoops ? If none  or worse a cost, the temptation not to bother will be strong.

Mike.

Fewer I suspect. If you just connect them, you can be immediately disconnected from the public electricity supply when they are found. 

Regards,

Alan. 

There is also a safety issue for both the homeowner and the DNO, connecting generation to run in parallel with the public supply. 

Regards,

Alan. 

Zoom, if it were me, I would consider concentrating upon the Fly paper problem and leaving this install to A N Other

Alan Capon: 
 

There is also a safety issue for both the homeowner and the DNO, connecting generation to run in parallel with the public supply. 

Regards,

Alan. 

…and due to fires/shocks from incorrectly specified equipment etc

I doubt that many grid tie inverters will be installed without the paper trail as this is a requirement for achieving the payments.

EV chargers might well be installed without paperwork, much as showers are.