Metering and monitoring for microgeneration

You may have noticed that I’ve just added an “M&M” category for posts about metering and monitoring technology. I haven’t really talked about these devices yet but they’re an integral feature of microgeneration installations and play a big role in promoting household interaction with these technologies.

There don’t seem to be any hard and fast definitions for these things but here’s what I’ve been using:

• Monitors

Monitoring devices record and/or display information about the electricity produced by a microgeneration system (and sometimes household consumption as well). Importantly the information gathered by these devices is not used for ‘fiscal’ purposes, i.e. billing. It simply provides information to the household in an accessible manner, e.g. visually or for download to a PC. There is a wide range of monitoring devices available on the market but here’s a top-of-the-line example from Sharp.



I’ll discuss these devices in more detail in a later post.

• Meters

Metering technology is used to record flows of electricity for billing purposes (often the information isn’t used for this purpose but the important thing is that is could be). Here’s a simple example:


There are potentially three types of meters in a microgeneration household:

1. Import: Required by law for all electricity customers, this meter is typically read twice a year in the UK as a basis for your electricity bill. Ofgem allows suppliers to charge £1.12 per year for operating these devices so there is strong competition in manufacturer and maintenance.
2. Export: These meters measure the flow of excess electricity returned, or exported, to the national grid. There is no requirement on any actor within the electricity network to provide these devices and so if you want one, you either have to rely on the goodwill of your supplier (and district network operator who provides the meter to the supplier) or pay about £200 from your own pocket. Some suppliers use these meters as a basis for payment for microgenerated electricity.
3. Generation: Generation meters record how many kilowatt-hours have been produced by your microgeneration system since its installation. Instead of export payments, many suppliers offer generation tariffs based on data from these meters.



Since having three seperate meters is a bit of a nuisance, there are also discussions underway about whether advanced metering technology, which combines many these features, might be introduced in the UK. More on this in a later post.