The new farm from Solarshare is expected to make $360,000 a year, including money coming from ACT government subsidies it agreed to with the government on Thursday.

Investors will be able to buy shares in the farm and receive dividends from the energy sold back into the national energy grid.

SolarShare principal executive officer Lawrence McIntosh said it was a sign of growing interest in Australia's solar market.

"Our objectives are to really involve the whole community," Mr McIntosh said.

Construction of the one-megawatt site will begin mid-to-late next year opposite the Mount Majura Vineyard, generating enough electricity to power 260 homes.

The farm will also prevent 1700 tonnes of carbon dioxide polluting the atmosphere, according to the company, and produce about 1.8 gigawatt hours per year.

"It'll be the first of this level of public accessibility in Canberra," Mr McIntosh said.

"All our energy leaves the farm gate and then we sell it to the energy market, we can't sell that anywhere else," he said.

He said the project would allow people unable to install their own solar assets, like renters or apartment owners, to invest in renewable energy, and would allow them to be more involved in their energy choices.

Most homes use between 10 and 20 kilowatts a day of electricity, he said, with a one-kilowatt share in the farm costing about $2000.

The minimum investment is $500, or 50 shares at $10 each, with the maximum investment at $100,000.

SolarShare has 284,800 shares, worth over $2.8 million, and the company hopes to attract between 400 to 600 investors.

The ACT government would be subsidising the farm to the tune of $195.60 per megawatt hour for 20 years, with the farm expected to generate between 1800 to 1900 megawatt hours a year.

This allows the farm to sell into the energy market at a rate of at least 19.5 cents per kilowatt hour, with any difference made paid to the ACT government.

The company's Offer Information Statement estimated a return of about $1.16 a share in the first financial year of operation, 2020-2021.

The return on each share would drop over the 20-year guarantee, but the statement estimated returns to hover around 90 cents for at least the first 10 years.

Running costs would be absorbed by the 19.5 cent price, but Mr McIntosh said the farm was running for the benefit of its members, like Bendigo Bank.

"We're not here to make a profit," he said.

"We're here to make sure the members of our community are the ones that reap the benefit of that financially, environmentally and socially."

The ACT government has guaranteed the subsidy, known as a feed-in tariff, as part of its efforts to have the territory using 100 per cent renewable energy by 2020.

The SolarShare farm will be the government's most expensive investment in renewable energy.

The three existing solar farms in the capital, including Royalla in the ACT's south, receive about $186 a megawatt hour.

The Hornsdale wind farm in South Australia receives $91 per megawatt hour, the Windlab wind farm in north-west Victoria receives $92 a megawatt hour and the Ararat wind farm will receive $87 per megawatt hour.