Solar PV Extension and Export meter

[Iain123]

Hi Solar Forum


An extension to a solar pv system will require a newgeneration for the extension, I understand that.
The existing solar pv system has an export meter.

Will the extension to the solar pv system also requireits own new dedicated export meter?

The reason I ask is because the existing pv systems exporttariff rate will be different to the extension pv export tariff rate.

Thanks in advance
Iain

 

[Gavin A]

and here were have the major flaw to DECC's meddling.

it's not possible to install 2 export meters on the same installation - what's exported is exported no matter how many meters you install.

You'll be wanting to contact Ofgem for guidance on this, or at least checking their guidance docs (or waiting for the oracle of the regulations known as Ted).

My guess would be that they'll expect you to assign export pro rata, so if it's 2 x 4kWp systems the export would be split 50/50 between the 2 systems. I'm not sure on that, but it's how it is supposed to be done for generation if you extend the panels using the same inverter.

 

[Iain123]

Hi Gavin

Thanks for replying and explaining how the same generation meter is used on a extension when using the original inverter.

This PV extension will be on a new inverter therefore the new generation meter. I had though the export may be done on a pro rata basis, I need to try and confirm this.

In any case I believe, if two separate export meters were used (one meter each for the two inverter/consumer unit pairs) on a single phase, the export from one meter could feedback (where the exports are connected in parallel before the import meter) in to the other consumer unit (and vice versa without being measured by the import meter). This would/could result in the export meter/s showing higher readings than the power actually exported.

Iain

 

[TedM]

Just because you have a second inverter doesn't mean you need a second gen meter as well.

The guidance requires any export meter to be next to (or incorporated in) the import meter. If there is a split in the tails straight from the import meter then you would have to add Henley blocks to get a common wire pair to fit the export meter (if you are fitting one yourself) or leave it to the DNO/MOP to sort (who would do something similar but most likely install a single meter with dual import/export function).

With common metering between systems on differing tariffs then the readings are pro rated based on TIC.

 

[Iain123]

Thanks Ted

for making things clear

Iain