Sustainable House Feature.

Sustainable House Feature. Photo: Damian White

THE RUSH to join ActewAGL's solar power generation scheme before its price offer was reduced has meant the number of Canberra households signed up at the ''generous'' higher rate, deemed unsustainable, almost doubled.

Nearly 1900 Canberrans applied for ACTEW's solar buyback scheme between when the price cut was announced on June 13 and the sign up deadline on June 30.

There were 2350 active solar generators in the scheme before the announcement, along with about 10,000 households who had signed up to a previous ACT government feed-in tariff offer on solar.

ActewAGL's general manager retail Ayesha Razzaq.

ActewAGL's general manager retail Ayesha Razzaq. Photo: Lyn Mills

Under the change, ACTEW will pay households at the commercial rate for the excess power they generate after powering their own homes, currently about 7.5 cents a kilowatt hour.

For those who signed up before July 1, ACTEW has been buying all the power generated by households at a rate of about 18 cents a kilowatt hour.

ActewAGL's general manager - retail Ayesha Razzaq said the scheme was changed because it was unsustainable to continue paying customers at the higher rate, and the new system brought the ACT into line with other states.

But she denied it had been a mistake to announce the price cut more than two weeks in advance, rather than closing the offer overnight as had been done when the government's feed-in tariff offer ended.

''It was appropriate to provide notice to our customers and we remain happy with the decision,'' she said.

Ms Razzaq said people who installed solar panels of a suitable size, usually between two and three kilowatts, would be no worse off under changes to the scheme. The new system would see households using their own solar power first, she said, which would save them buying it at the going rate of about 18 cents a kilowatt hour.

She blamed misleading advertising by solar panel installers for the rush to sign up to the old scheme before July 1.

''That's solar installers and marketing campaigns, which we don't have control over and that's what happened,'' she said.

Ms Razzaq said about 1.6 per cent of Canberra's energy needs were supplied by household solar generators.

Two households had applied to sell ActewAGL solar power after July 1.

Customers were required to submit a Special Connection Form by the end of June to sign up to the higher rate, and now have until September 30 to get their generators installed.

''If what ends up being installed is different to what was nominated on the form, the customers need to resubmit a new form, which then obviously means they're not eligible for that [old] gross metering scheme,'' Ms Razzaq said.