EMMA with Export Control

Note: EMMA with EC (Export Control) is the new name for EMMA GVS.

Avoid network upgrade costs

An optional Export Control (EC) add-on is available for all EMMAs. EC lets you control how much electricity is exported by your generator - even very large generators - so electricity exports stay below any limit set by the Distribution Network Operator (DNO). This makes it possible to install large PV arrays and turbines where it would not otherwise be permitted.

The EC add-on is normally not needed for domestic generators, or for sites where the DNO permits the full export capacity of the generator.

Instant Savings

By letting you avoid network upgrade costs, EMMA with EC could save you £8k to £15k instantly - before the ongoing savings that EMMA gives you. Network Operators agree that EMMA with EC is often a more sensible, simpler and cost-effective solution than upgrading the network.

EMMA with EC

  • Designed for sites where the DNO limits how much electricity you can export
  • Overcome limitations imposed because of network capacity
  • Control electricity exports to DNO limits.
  • Allow the export current of 16amps under G83, while the rest is sent to heating loads and other uses onsite.
  • Avoid expensive network upgrade costs.
  • Prevent costly inverter outages.

See graphs of EMMA with EC in Action - Case Studies


Also see our blog entry: How EMMA with EC Works.

Why EMMA with EC makes sense to your DNO

Grid voltage regulation is a critical problem for electricity network operators (DNOs), particularly when numerous or large renewable generators are being connected at remotely located sites. It is normal to apply "diversity factors" of circa 0.4 or less to normal network loads when sizing distribution cables, transformers and switches - because normal loads don't all switch on or off at the same time. However, sun and wind powered generators ramp up and down simultaneously throughout local areas as gusts and clouds sweep by. This causes surges of electricity to be fed into networks which are not designed to cope with it.

Without EMMA these surges cause significant problems for the network. Standard EMMAs (i.e. without the EC add-on) just about eliminate this problem. EMMA with EC completely eliminates the problem.

Export Control Technical details

Typical EMMA with EC's export-limiting calculations are aimed at restricting exported current to 20 Amps when the system is at 253 volts, and allowing this to increase proportionately to the maximum output of the renewable generator when the system is at 216.2 volts. It does this by diverting surplus power to a thermal store or other secondary devices - such as onsite heating and cooling devices.

The amount of power exported is kept to a minimum when surplus power is being diverted. The amount of current exported is kept below the approved limits at all times.

  • The export limit can be a fixed maximum export current, or an export current that varies the voltage within specified limits.
  • Clamp on CTs monitor the output from the generator and the site's current demand for electricity.
  • Grid voltage is simultaneously monitored.
  • Export is adjusted by varying the load within the household/farm as necessary.
  • This keeps the voltage within G83 guidelines and prevents inverters tripping due to high voltage.
  • Should the export current exceed a specified maximum value/duration (i.e. if all the loads are "full" and there is nowhere else to send surplus electricity), EMMA will temporarily disconnect the generator from the grid.

ELITE Control

The ELITE is the latest addition to the EMMA product family. While we consider it to be the Elite of power diversion and monitoring it is in fact EMMA's little sibling or as we call it EMMA lite.


EMMA Cascade

The modular heating system that can grow and grow


EMMA with Export Control

EMMA with EC allows for installs to have a greater renewable output than the Max Export Capacity (MEC) on site by diverting excess energy to heat.