Onsite generation and metering

Mae’r dudalen yma ar gael yn Gymraeg.

Is onsite generation affecting my meter readings and billing?

Since 2010, consumers have increasingly used the Feed-in Tariff (FIT) scheme to install renewable electricity generating equipment, such as solar photovoltaic (PV), on their homes.

Some consumers have found that their import supply meter, which measures electricity consumed, is affected by installing onsite generation such as PV panels or micro wind turbines.

Here we explain how your meter and billing might be affected, and who you should contact if you think there is a problem.

How is export electricity from onsite generation measured?

FIT installations with a total installed capacity of 30kW or less are not required to have an export meter to receive FIT export payments. Instead the export payments can be deemed. See the FIT metering requirements.

Who is affected?

Some consumers with an older ‘analogue’ meter – the ones with the rotating disc – are finding that the disc sometimes turns backwards, and the numbers on the meter are lower.

This happens when you generate more electricity than you are using, and your meter does not have a backstop (which prevents it going backwards). If this is happening you might be under-billed. You may not be paying for all the electricity you have consumed from the grid.

If you do not have an export meter and the import supply meter is not accurately measuring the imported electricity there is no record or way to calculate the correct bill.

This means once the metering issue has been discovered, estimates will be used to calculate the bill to rectify the under billing.

Some newer digital meters are configured to add any export electricity to the import readings. This might mean you are paying for more electricity than you are actually consuming. If your import meter is not accurately measuring the electricity you are consuming, even though you have readings from the generation meter, without an export meter your energy supplier may need to estimate your past bills.

What should I do if I am concerned?

If you are concerned that your meter is running backwards you should tell your energy supplier (who might be different from your FIT supplier) as soon as possible.

If you are not seeing the savings you were expecting from the onsite generation, speak to your installer about the savings estimates they predicted.

If, once your installer has checked the system, you are still concerned, please contact your energy supplier. Once the supplier is aware that the meter may not be suitable, they must ensure the meter is appropriate. This responsibility has been put on suppliers through Schedule 7 of the Electricity Act 1989.

I have been advised by my installer that a backward running meter is a benefit of the FIT scheme?

A reduction in a customer’s electricity bill caused by a backward running meter is not a benefit of the FIT scheme. Consumers should continue to be metered, and billed for the import electricity they use.

If you have been misadvised by your installer you should contact the Renewable Energy Consumer Code (RECC).

For further help and advice, contact the Energy Saving Trust:

  • For England and Wales, contact them for free on 0300 123 1234 or email energy-advice@est.org.uk.
  • For Scotland, contact them for free at Home Energy Scotland on 0808 808 2282.

How will my supplier know how much electricity I have used? Can my supplier back bill me?

If there is no export meter and the import supply meter is not accurate, there is no way to calculate the correct bill. This means once the metering problem has been discovered, estimates are used to calculate the bill to rectify over- or under-billing.

Ofgem and energy suppliers have discussed resolving disputes, and what Ofgem expects from suppliers. You should ask your supplier to confirm its procedures. One example of best practice is where an estimate is based on previous consumption history, takes into account the type and size of the generation equipment, seasonality, and is made after a review period once the meter has been exchanged.

Smart meters and onsite generation

The government plans to install smart meters in all homes across England, Scotland and Wales by 2020 will provide consumers with greater information on their use of electricity. The technical specification for these meters includes the ability to measure exported electricity. As older meters are replaced we expect fewer consumers to be affected by these issues. 

More guides

Publications and updates

  • Published: 30th Apr 2013
  • Factsheets
  • 1 Associated documents
This factsheet explains flexible energy use, how demand-side response works and how being flexible with how and when you consume electricity could save you money.