The cost for an average household paying for the government's feed-in tariff scheme has reached about $26.40 a year and Environment Minister Simon Corbell expects this to jump to about $50 late next year.

Meanwhile, those who have had solar generators installed receive on average almost $800 a year for the electricity they generate.

The feed-in scheme compares poorly to ActewAGL's Greenchoice program. During 2011, its more than 20,000 customers bought 2.54 per cent of the ACT's annual electricity requirement for less than half the cost of the government's feed-in scheme.

Under the federal government's mandatory renewable energy schemes, ActewAGL was required last year to buy 5.62 per cent of electricity sales from large-scale renewable generators and 14.8 per cent from small-scale renewable generators.

ActewAGL general manager retail Ayesha Razzaq said ActewAGL's fully accredited GreenPower program allowed ActewAGL to purchase renewable energy from sources such as hydro, windpower and biomass on behalf of customers. This electricity would otherwise be sourced from fossil fuels.

ActewAGL general manager network services Rob Atkin said that on April 16, there were 10,566 solar sites connected to the ActewAGL network.

From April 1 last year to March 31, the energy produced by photo voltaic systems in the ACT was estimated at 0.7 per cent of the total demand.

These systems contributed nothing to the peak winter demand because at that time, without sunlight, they were not operating. During the summer peak, solar photo voltaic systems contributed about 0.47 per cent of that demand.

Mr Corbell said the ACT micro feed-in tariff scheme was initially capped at 30 megawatts. This was increased to 35 megawatts on a Greens-Liberal amendment to reflect the introduction of the medium scale category. This would cap the maximum annual cost to the average ACT household at $50.