Export Limitation

[Stuart Houghton]

I received a call from a person who was not a customer of mine asking to connect up his 8 kW PV system.

Its a new build and the modules were installed when the scaffolding was up, this was several months ago.

System is 2 x ABB PVI 3.6-TL-OUTD inverters connected to 32 x 250 watt modules. The inverters are installed in the loft area and two twin & earth's have been installed back to the C/U.

The original installation company did not complete a G59 application and I have just done this but SSE have come back and they want £20k to upgrade their transformer and then they will allow the full 8kW to be connected. Obviously, my customer is not going to pay £20k !

He could just connect up one system but as its a large house with a wedding venue attached to the same supply he would like the full 8kW connected.

There is a system manufactured by Siebert but this needs a data wire installed from the intake to the inverters which as the house is nearly completed would be impossible to install without a lot of damage to the house.

Can anyone think of a way that would limit the total export to 3.69 kW which would keep the DNO happy ? off the top of my head I was thinking of some sort of battery system that one of the inverters could be connected to and then it would discharge via a transfer at night ??

All thoughts appreciated.

 

[Gavin A]

I think the sibert option can function without the link to the inverters, just by fitting a contactor to cut off one of the 2 inverter circuits if export exceedes 3.68kW

 

[PEG]

Hi,who was responsible for the original survey? ...They weren't by any chance,recently unemployed from an Irish renewable Co.

 

[SibertSolar]

Gavin's correct - our independent electro-mechanical failsafe can simply shut down the inverter if the absolute export threshold is breached. However, if no comms link to the inverters is present then, technically, you are not fully compliant with the ER G100 framework, which requires "granular monitoring data upon request". You would also not avail of the full energy flow monitoring through the facility (generation, consumption, grid-exchange) and also no inverter events/alerts/failures etc would be monitored or reported on. You would also lose the facility of maximising on generation at all times - just leaving a binary on/off scenario for the 2nd inverter.

However, in this particular instance, a simple shut down of one of the two inverters if >3.68kW is exported back to the grid, with an adjustable auto-reset timer, may well be adequate to appease the DNO.