Over 900 jobs have now been lost at the Leicester-based business as Deloitte were appointed as administrators on 07 October.
The firm employs 1,165 people across the UK, with more than 700 based at its headquarters in Beaumont Leys.
In a statement, the company said: "This decision has not been taken lightly but the ongoing losses of the business meant it was our only option.
"The turnaround plan, which was already underway, focused on solar PV but the Government's recent policy announcements mean this is no longer viable.
"Mark Group is now in the hands of administrators who are working to secure an urgent sale of the ongoing business."
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The Sustainable Energy Association (SEA) has called on the Government to rethink its approach to energy policy after the collapse of the business.
Dave Snowden, SEA Chief Executive, said: "This is disastrous news for the thousand or so employees that have left Mark Group buildings today to tell their families they no longer have a job, and could easily have been avoided if the Government had paid attention to clear signals about the need to instil confidence in the market.
"Ministers were warned long before the election of a confidence problem in the sector due to lack of clarity on policy and frankly could have easily prevented this.
"The Government's rhetoric on meeting climate change targets, on placing energy efficiency at the heart of energy policy and the effusive support given by Ministers for solar, today feels hollow and empty.
"There can be no stronger case for quickly filling the policy vacuum in all these areas affecting energy measures in buildings and we call on the Government urgently to agree to a new Energy White Paper that properly places buildings at the heart of energy policy."
(LM/CD)
