Trade body Scottish Renewables said the figure could even be close to £1.5bn which would be almost double the £757.2 million recorded during 2011.
The analysis of the sector is based on data provided by the Department for Energy and Climate Change (DECC) regarding how many megawatts of renewable power were installed in the first half of 2012.
There were 611MW brought onstream between January and the end of June with onshore wind responsible for 572MW.
Using estimates from global engineering consultancy Mott McDonald of how much is spent to provide each MW for each type of technology Scottish Renewables is able to give investment totals.
The overall figure, revealed at the Scottish Green Energy Awards in Edinburgh last night, was £909.7m at the half-year point and the trade organisation expects the £1bn barrier has already been broken.
Onshore wind continues to make up the bulk of investment and was at £800.8m in the first six months of this year.
Niall Stuart, chief executive of Scottish Renewables, said: "DECC figures show Scotland's renewable energy sector delivered some £900m of investment in the first six months of 2012, putting us firmly on course to exceed an annual total of £1bn for the first time in the industry's history.
"More than £800m of this came from onshore wind, showing the importance of the sector during a challenging time for Scotland's economy. That investment is of course supporting thousands of jobs across Scotland in project management, civil engineering, professional services and operations and maintenance.
"This year could see more than double the level of capital projects delivered than in 2011. We attracted around £750m of investment in the entire year of 2011 and more than £900m in just six months of 2012. If we continue at this rate there's a good chance we could see in excess of £1.5bn of capital projects."
By the midpoint of 2012 there were more than 5450MW of installed renewable energy in Scotland.
In a separate report out today members of the Civil Engineering Contractors Association (Scotland) (CECAS) said they had seen £300m worth of work from the renewable sector between October 2011 and September 2012.
The organisation said this was around 15% of the estimated £2bn of infrastructure activity in Scotland during the 12 months.
CECAS chairman Roger Philpott, of Perth-based contractor I&H Brown, said the renewable energy sector was up with Transport Scotland and Scottish Water as a provider of work.
He added: "This is all the more important during a recession where renewables is one of the few growth areas in a Scottish construction market that has suffered a dramatic downturn and significant business failures."
CECAS estimated money spent on renewable energy infrastructure has helped preserve between 2000 and 3000 jobs and said many smaller members in more remote parts of the country had relied on the sector to keep going. Contractors were confident spending on renewable energy infrastructure would grow in 2013.