Armada Solar, one of the city's longest-running rooftop solar companies, which also installed double-glazed windows, went into liquidation last week.

Liquidator Tony Lane, of Vincents, did not have a final count for the number of Canberrans caught up in the collapse, but said there were a range of customers at different stages of completion of projects. The deposits, which varied from 5 or 10 per cent of a project to 50 per cent or more, were spent by the company, he said.

Creditors, including people who had paid deposits, were believed to be owned more than $1.8 million, a figure that could rise, he said.

Company owner Justin Ryan said he wanted to help people left in the lurch by the collapse. Mr Lane was writing to customers late on Wednesday to establish how many wanted to pursue the offer, but had no details on how Mr Ryan might be able to help.

"We are actively exploring what ability the company or a related entity may have to complete that work. However, there are a number of variables that will need to align in order for that to happen," he said.

In the wake of the collapse, Greens Legislative Assembly member Shane Rattenbury signalled a push for a new guaranteed feed-in tariff to encourage Canberrans to install rooftop solar panels to help the industry.

Mr Rattenbury said the tariffs offered by ActewAGL of 7.5 cents a kilowatt hour and Origin of 6 cents were voluntary. The companies set their own price and were not obliged to pay for solar power generated from new rooftop installations. This meant people who installed solar panels had no certainty about future payments.

"If you're generating electricity and feeding it into the grid you should be paid a fair price for that," he said. "We need to put something in place in the territory. We have got too many roofs that are not being used."

Mr Rattenbury wants a guaranteed price over a specified number of years, but said it wouldn't be as much as the 50.5 cents a kilowatt hour for 20 years paid to customers who signed up to the previous ACT scheme before it was scrapped in 2011.

Almost 1100 people are signed up to the scheme and were paid an average $1690 each over the past 12 months for the solar power they fed into the grid. A number are not only covering their electricity bills but are making money.

Mr Rattenbury said Canberrans had already shown their willingness to install solar panels on their roofs and just needed a consistent long-term price that provided a reasonable incentive.

"We are building large-scale solar farms in the ACT already, and financing new wind farms outside the ACT. For the same or less cost, we could also utilise a great resource that we already have in place – thousands and thousands of suitable roof spaces that could be filled up with solar panels that can feed green electricity into the grid."

The solar industry put part of the blame for the Armada collapse on "rollercoaster" changes, including the boom of the generous feed-in tariff and the bust when the scheme was closed.

However, Environment Minister Simon Corbell said while there was a drop-off, there was still a market for rooftop solar energy. Nearly a third of all domestic rooftop solar installations in the territory - 4847 out of 15,029 at September last year - had been installed without access to a government feed-in-tariff, he said.