Demand Side Management

Discover how Demand Side Management and Demand Side Units work to control electricity demand.

What is Demand Side Management?

Demand Side Management is a way of controlling electricity demand. It encourages customers to reduce their electricity use, either during peak hours or their overall use. It can offer significant benefits for customers, including lower bills.

Demand Side Management is key to system security for Ireland. It helps us to manage the power system efficiently, including:

  • More renewable electricity generation 
  • Enhanced capacity

How to Participate

Electricity consumers can participate in Demand Side Management through tariff-based schemes. Examples include: Economy 7 (Northern Ireland) and NightSaver (Ireland). 

EirGrid operates two system operator-based schemes in Ireland, aimed at large electricity users: Short Term Active Response (STAR) and Powersave. These keep the system secure at times when it is under stress. 

Medium to large electricity users can also participate in a Demand Side Unit (DSU) or Aggregated Generating Unit (AGU).


What is a Demand Side Unit (DSU)?

A Demand Side Unit (DSU) is a demand site that EirGrid can instruct to reduce electricity demand. These are called dispatch instructions.

Individual demand sites are typically a medium to large industrial premises. When a DSU consists of more than one individual demand site, it is called an aggregated DSU. These are combined by a DSU Aggregator, which is a third party company specialising in demand side participation.

DSUs that are available for demand reduction are eligible for a capacity payment in the Single Electricity Market (SEM).



Demand sites can register as a DSU, whether or not they have a Maximum Export Capacity (MEC). They must have a demand reduction capacity of at least 4 MW.  

For aggregated DSUs, the maximum demand reduction capacity of an individual demand site is 10 MW. Demand sites with more than 10 MW demand reduction capacity can register as a stand-alone DSU. 

The company registering the DSU must be a licensed supplier registered in the SEM. It is not required to be the supplier of the individual demand sites. 

DSU Dispatch Instructions

We issue dispatch instructions at an aggregate level. The DSU Aggregator then coordinates the reduction from the individual demand sites. DSUs use a combination of on-site generation and plant shutdown to reduce their demand. 

We require real-time communications with the DSU. DSUs must be available 24 hours a day year-round. This is to ensure we have a secure power system and can issue dispatch instructions quickly. The exceptions are a breakdown or an agreed outage. 

When you become a DSU, you receive a signal list. You can use this to configure your control system to provide these signals. We issue dispatch instructions using the Electronic Dispatch Instruction Logger (EDIL).

Apply to Become a DSU

To become a DSU, you must apply to both EirGrid and the Single Electricity Market Operator (SEMO). The application to EirGrid can be made using the approved application form with all relevant documentation included. Please contact us by email for further information.

Email: dsu@eirgrid.com