The government's decision to reduce individual grants for homeowners wanting to produce their own renewable energy has been criticised.
About 240 micro-turbines have been installed under the scheme
Changes to the Low Carbon Buildings Programme mean that future applicants will be limited to £2,500 for domestic micro-generation projects.
Previously, grants of up to £15,000 and £5,000 were available for solar energy and micro-turbine schemes respectively.
Ministers said the changes would enable more people to participate.
Flood of demand
Demand for the scheme, introduced last year, has been intense with monthly allocations of money being fully subscribed within minutes.
Grants worth £6.8m have been awarded so far and a further £11.9m in funding is available.
However, less than £3.5m of the money has been spent, following planning hold-ups, delays to building schedules and flawed applications.
This has led some people to claim that the scheme - a key plank in the government's efforts to promote energy efficiency - is in crisis.
The application process was suspended in March pending a review, which has resulted in a cut in individual grants, a reduction in the time people have to finish projects and a revamp of the application process.
Companies involved in micro-generation criticised the decision to reduce individual grant levels, one describing it as "unnecessary and baffling".
"There is no justification for the decision in terms of strategy or support for domestic renewable electricity market," said Seb Berry, external affairs director of Solar Century, which designs and installs solar panels.
With the typical cost of buying and installing a solar panel system about £7,000, Mr Berry said the changes would make the project unviable for many people.
"You are asking individual homeowners to find £4,000 to £5,000 of their own money."
Bu the government defended alterations to the scheme, saying it would ensure more projects were completed and help domestic renewables become more self-sustaining.
"We can't fund everybody in the country who wants to do it," said a DTI spokesman.
"We have a limited amount of money and we want to spread that as far as we can."