ActewAGL has received 831 applications to lock in the solar buyback scheme since it was announced that it was being phased out and replaced by net metering on July 1.

To qualify for the scheme, customers need to lodge a special connection form with ActewAGL by 5pm on Friday or through an email by 5pm on Sunday and have the system installed by September 30.

ActewAGL general manager of retail Ayesha Razzaq confirmed on Thursday that customers who fail to meet those deadlines would be subject to the new net metering system that pays about 7.5¢ per kilowatt hour.

Those who meet the deadlines will receive about 18¢ per kilowatt hour and will remain on that scheme until June 30, 2020.

''Customers should confirm with their installers that they'll be able to meet these deadlines before committing to the purchase because ultimately it's not up to ActewAGL - we just provide the guidelines. It's up to the customer to pick a reputable solar company and ensure they meet the deadlines,'' Ms Razzaq said.

Armada Solar director Justin Ryan said one out-of-town company had contacted him looking for installers after running a campaign to get customers to sign up. The apparent lack of manpower within the company was a concern.

''This potentially will lead to a situation where a number of Canberrans pay a deposit to interstate companies who are not going to deliver by ActewAGL's deadline,'' he said.

Mr Ryan said his Canberra company was close to capacity and his concerns were not about ''drumming up more business'' but ensuring that the industry was acting ethically.

He said the other concern was advertising where companies filled out connection forms in advance and distributed them to potential customers without investigating whether the system recommended was the right fit and orientation.

Ms Razzaq, who was aware of the practice, said it would become an issue if the installed system was different from what was stated on the form. In that case, the form would have to be resubmitted, the deadline would be missed and the household would face net metering.

Ms Razzaq said installers did not necessarily need to visit each household, as reputable companies used special technology, similar to Google Earth, to map the appropriate roof system.

She confirmed that the changes only applied to ActewAGL's solar buyback scheme. ''Customers receiving solar generation payments under the terms of the ACT government feed-in tariff scheme are unaffected by this change,'' she said.