Advocates say the ability to export electricity, resulting in lower overall electricity bills or even receiving a cheque from the ESB, is essential for encouraging investment and lowering the effective cost of renewable power.

Both the ESB and the Commission for Energy Regulation (CER) have confirmed that no final decision has been taken on whether the meters used will allow people to export power.

Some industry sources have indicated that the ESB may try to adopt a two-tier approach to smart metering, where it will install basic meters that cannot sell power as standard and will charge homeowners extra for more advanced meters that can export power to the national grid.

This would put the company on a collision course with the new energy minister, Eamon Ryan, who is said to be keen to promote microgeneration.

Ireland lags behind Europe in microgeneration, where households produce their own power and sell any excess to the national grid, because the electricity meters used by the ESB cannot credit homeowners for exporting power to the grid.

Britain has over 90,000 microgeneration installations and a study published last year showed 30% to 40% of all its electricity needs will be provided by the technology in 2050.

According to Sean Porter, managing director of Futumeter, an Irish company that sells smart meters, the use of the term 'smart meter' was no guarantee that the meter would be able to export power.

"Not all smart meters are equal. There are so many different types, some of which don't offer the ability to export, " he said. "To be honest, if the powers that be decide on a metering system that goes under the heading 'smart meter' but is not that smart after all, then we would all be better to stick with the old metering system we have."

Porter said the choice of meter would have a major effect on the uptake of microgeneration in Ireland, particularly as it was a major long-term investment for homeowners and businesses.

"Microgeneration has good potential but is a long-term investment. Its affordability depends on the conditions it gets from the electricity provider and the system it chooses for generation."

John Quinn, managing director of Surface Power, a company that sells microgeneration equipment, said he was confident the ESB would opt for smart meters that could export power.

"They are required under European law to calculate the amount of green energy we are producing. Ireland can't just go it alone. If they did, they would be making a statement which would be illegal under European law, " he said.

A spokesman for CER said no decision had been made regarding the type of meter that would be used. He said, however, that it was probable they would be able to export. An ESB spokesman said the smart meter project was in its early stages and "certainly a consideration would be the installation of meters with the capacity to export".