Avoid network operator limits

Avoid network operator limits and install renewable generators of any size you want – using EMMA GVS.

Managing export limits


The Proven wind turbine which has been installed with an EMMA GVS, at Kinvarra, Co. Galway

A customer in Kinvarra, Co. Galway is the first owner of a 13.7 kW Proven 35-2 wind turbine to have an EMMA GVS installed. The EMMA GVS allows the customer to connect his wind turbine to the grid on single phase and still receive his feed-in-tariff payments from ESB for 6kW/hour export.

ESB gave the go ahead for the turbine with the condition that it had the EMMA GVS to limit export to the grid to 25 amps.

Using wind energy to heat house and hot water

When this export limit has been reached, EMMA GVS sends any additional power to an immersion heater in a 1000 litre buffer tank which supplies the hot water and central heating, so preventing over-export to the grid. When the tank reaches its desired temperature, EMMA sends power to a further a bank of dump loads. In other words, EMMA is able to heat both the house and the hot water:

  • The priority of the EMMA GVS, in this case, is to send power to the 1000 litre buffer tank with two 5 kW immersion elements. The tank is heated by EMMA and also by an oil boiler.
  • The buffer tank was installed at the same time as the wind turbine. It sits between the existing oil boiler and the central heating and domestic hot water. In other words, the tank takes the place of the oil boiler in the central heating circuit.
  • The EMMA heats the water in the tank and the hot water is circulated around to the radiators as usual.
  • There is a switchover valve to switch the flow of hot water to the indirect hot water cylinder.
  • If there is no wind to drive the wind turbine or the tank is not hot enough to heat the house the oil boiler will engage and heat the buffer tank – so hot water and heating are available whatever the weather.

The EMMA GVS is programmed to heat the tank to 85°C and then switch over to the bank of dump loads which are three resistive convection heaters making a 9 kW load. At this point the EMMA GVS will balance an export of 25 amps (5.75kW at 230v) (which will provide feed-in tariff payments for the owner) and send the excess power to the dump loads.

Bypassing NC6 regulations

In this case EMMA GVS allows the connection of a larger turbine to the grid than under the NC6 regulations. The advantages to the owner are:

  • generate more income from the turbine (from feed in tariffs)
  • incur a smaller per kW installation cost (i.e. economy of scale)
  • Furthermore EMMA will divert the extra power to heating, so reduce the oil bills.

Preventing over voltage trips

Proven turbine with EMMA GVS, Kinvarra, Co. Galway

Another crucial task that EMMA GVS does here is to protect the wind turbine system from outages due to over voltage. Over voltage trips occur when the voltage on the grid is high (253v). This trips out the inverters and means a loss of valuable power, typically in windy conditions.

EMMA GVS prevents this occuring by sending more power to the heating as the voltage approaches 253 volts. By using more of the power available from the turbine the Grid voltage can be stabilized to prevent the inverters tripping out and losing out on valuable power.


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