FAQs

The system design showing the meters will need to be submitted to Ofgem for verification.

Chapter 7 of the government’s RHI announcement says

Verification

For all participants seeking accreditation for the RHI, Ofgem will require submission of a schematic diagram of the plant. The schematic will need to include details of the plant and the location of meters and associated components. Where additional capacity/plant is added or there are any changes to the metering arrangements participants will need to provide a revised schematic diagram (and possibly other information) to Ofgem showing the position of the additional generation facilities and any changes to metering.

In certain circumstances, Ofgem will require an independent site report to be undertaken by a competent person to verify the schematic diagram. The RHI regulations and Ofgem guidance will set out where this applies. The cost of providing this information will be borne by the participant.

They will have to be recalibrated and maintained to ensure accuracy of readings.

Chapter 7 of the government’s RHI announcement says

Maintenance requirements for meters

Periodic calibration of meters should be carried out by the manufacturer or by United Kingdom Accreditation Service (UKAS) accredited organisations working within the scope of National Accreditation of Measurement and Sampling (NAMAS) procedures. Other devices should also be appropriately calibrated, for example static pressure gauges and temperature sensors.

New or replacement units should be accompanied by a calibration certificate from the manufacturer. Evidence of calibrations of steam (or heat) flow meters, including the primary flow device, would be expected to be available if a site were audited.

The participant will need to ensure that these requirements have been satisfied as part of the RHI accreditation process and, where appropriate, provide evidence to Ofgem.

On installation the meters will need to be properly calibrated. Periodic recalibration may also be required.

Chapter 7 of the government’s RHI announcement says

Maintenance requirements for meters

The RHI regulations will require that heat meters used to claim RHI payments are installed in accordance with the manufacturer’s instructions. Where meters are supplied as a package, comprising a flow meter, a pair of temperature sensors and a computer/integrator, they should be recalibrated or replaced in accordance with the manufacturer’s instructions.

For solar thermal, where appropriate, heat meters will need to be calibrated at the point of installation for any water/ethylene glycol mixture in the collector.

In principle you may have to meter both the heat produced by the installation and the heat delivered to the useful applications.

Chapter 7 of the government’s RHI announcement says

Metering of heat generated and used

The RHI regulations will describe the circumstances in which participants will be allowed to meter heat at the point of generation only and describe the circumstances where participants will be able to meter the heat generated by more than one plant using a single meter. In systems where only the heat generated is metered, heat meters will be need to be located to ensure that the contribution of the renewable plant can be calculated. Fossil fuel installations on the system do not need to be metered, but their generation must be kept separate for metering purposes from the generation of each metered renewable heat installation. Where different renewable technologies are installed (for instance biomass boilers and heat pumps), separate meters will be required to determine the heat generated by each renewable technologies. Where additional capacity is added to a heating system later, participants will have to meter the additional capacity separately from the originally installed capacity.

Participants using heat pumps to provide both heating and cooling will need to ensure that their metering arrangement does not count any cooling generated by the reverse operation of the heat pump. Participants will need to measure the eligible renewable heat generated, and provide the appropriate cumulative meter reading(s) to Ofgem. They may also need to provide an explanation of how their metering arrangement has enabled this figure to be calculated.

Where additional meters are required for the RHI, all generating installations feeding heat into the heating system (including fossil fuel plants) will need to be metered. Participants will be required to meter the proportion of heat used for space, water or process heating to ensure that payments are not made for heat that is wasted or ineligible for RHI support.

By measuring the volume of gas injected and its calorific value

Chapter 7 of the government’s RHI announcement says

Metering of biogas and biomethane injection to the gas network

Biomethane producers who wish to receive RHI support will be required to measure to Ofgem’s satisfaction the volume and gross calorific value of biomethane injected to the gas network and convert the resulting measurements to a kWhth figure. Measurement of the volume and gross calorific value of any propane added to the biomethane is also required. The biomethane producer claiming the RHI will be required to measure any external heat input to the biogas plant which made the biogas used to produce biomethane (such as heat from natural gas or other renewable heat technologies). The RHI participant will have to deduct these elements from the meter reading and provide the cumulative kWhth figure to Ofgem together with details of all individual measurements.

Using the standard heat metering process, but certain deductions may be required.

Chapter 7 of the government’s RHI announcement says

Metering of biogas and biomethane injection to the gas network

In addition to the relevant metering requirements, where plants generate heat from biogas, participants will have to additionally meter:

• any heat directed from the combuster to the biogas plant;
• any heat to the biogas plant derived from any source other than the biogas itself.

These measurements will be deducted from the meter reading on which RHI support is claimed. Both the cumulative meter reading and the supporting calculations must be provided to Ofgem.

You need to use a Class 2 heat meter. There are specific requirements for which heat outputs need to be measured, how the meter is configured in the system and how it is calibrated and maintained.

Chapter 7 of the government’s RHI announcement says

Meter requirements

As RHI payments will be made on the basis of heat meter readings, the Government will require participants to use meters that have met certain standards to provide assurance that payments are based on accurate measurements and to consumers that their devices are reliable. Tampering with meter components (to influence the meter reading) constitutes fraud and will be dealt with accordingly.

A wide variety of different types of heat meters are available commercially. The Government will allow those who wish to claim the RHI to choose to use any heat meter that meets the Class 2 requirements listed in Annex MI-004 of the EU Measuring Instruments Directive (MID) 2004. Requirements for measuring steam are covered separately.

No specific standards have been set, but reference is made to the Carbon Trust’s guidance note.

Chapter 7 of the government’s RHI announcement says

Measuring steam

Accurate measurement of steam is possible but represents particular challenges. In particular, it requires a higher degree of accuracy and entails higher costs. Where boilers are used to produce steam rather than hot water, the regulations will require measuring equipment that accurately measures flow rate, temperature and pressure. Participants must provide the appropriate metered steam figure to Ofgem having deducted any condensate returned to the boiler or steam used for ineligible purposes. This could be achieved by metering these items separately.

Guidance on choice of appropriate steam measuring equipment and installation and maintenance can be found in the Good Practice Guide (GPG018) available from the Carbon Trust.