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Can I increase the capacity of my PV system if I am claiming ROCs?

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Can I increase the capacity of my PV system if I am claiming ROCs?

Under the Northern Ireland Renewables Obligation (NIRO) scheme, you can claim Renewables Obligation Certificates (ROCs) on the total units generated by your photovoltaic (PV) system each year. Before the NIRO scheme closed in March 2017, anyone wanting to join PV systems together or increase the capacity of an existing system, could do so by amending their existing ROC application and applying for 'additional capacity'. 

This required the details of ‘additional capacity’ to be updated on the original application, including the new Total Installed Capacity (TIC) and Declared Net Capacity (DNC), as well as the number of panels and their rating.

Payment for additional capacity is not eligible under NIRO since its closure, however it is still possible to add panels to your existing PV system to increase its capacity. This is referred to as ‘Unsupported Capacity’. You will be able to receive export payments on the additional capacity and you will continue to receive payments for ROCs generated by the original system. 

Provided Ofgem are made aware of the changes to the existing system, the unsupported capacity will not impact your annual meter reading submission and subsequent ROC payment. Ofgem will simply factor in the additional capacity, into their annual calculations and issue ROCs on the total eligible generation.

"If generators in Northern Ireland choose to add unsupported capacity, we will pro-rate output of the whole generating station across the TIC of the NIRO capacity and the unsupported capacity. Pro-rating is used where the capacities are metered separately and where metering is shared"

It is important to remember that any significant changes to the existing accredited system must be communicated to both your agent and Ofgem.

Generators are encouraged to inform their agent and Ofgem before making any amendments to their existing generating system. This is because Ofgem cannot release ROCs while an amended application is ‘under review’. Once Ofgem have reviewed and approved the amendments, the generating station will be able to resume claiming for ROCs for the original part of the PV system.

If you have any queries regarding adding capacity to your solar PV system, please contact our small scale PV team:

You can also find lots more information in the FAQ section of our Domestic Solar page.

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Nathan McBride

Nathan McBride
Project Manager


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