The Housing Executive is spending almost £200,000 to adapt some of its Belfast homes to run on solar power.
The move could cut tenants’ electricity bills at flats at Cregagh in east Belfast by a quarter.
The roofs of the flats are being fitted with solar panels to convert daylight into electricity.
The move has the potential to save tenants about £100 a year.
One tenant, Albert Barrett, said the heating he had at the moment meant his electricity bill was quite high.
Noel Rice of the Housing Executive said it had advised tenants that they should aim to be using most of their appliances during the middle of the day.

” The type of heating I have at the moment means my electricity bill is quite high ”  says Albert Barrett, Tenant
“We have advised them that this would be preferable between the hours of 1100 and 1400,” he said.
“It will work all day, as long as there is daylight, but it would be working at its maximum potential in the middle part of the day.
It may be environmentally friendly, however installing solar power equipment is not cheap.
It costs about £3,000 per house including grants.
However, the price is predicted to come down when solar power is more extensively used in Northern Ireland.
Homeowners across the UK can apply for a government grant to cover 50% of the costs of fitting solar panels to their roofs.
About 3,000 grants were made available last year as part of a three year £20m initiative by the Department for Trade and Industry.
The scheme aims to reduce the UK’s carbon emissions, bring down the cost of solar electricity and dispel the myth that solar energy is a non-starter in the UK’s climate. 
The sustainable energy drive is being run by the Energy Savings Trust and they hope to boost household solar installations ten-fold by 2005.
By that time, Germany expects to have 140,000 while Japan will have nearly 400,000 buildings powered by the sun.
Currently, only a very small proportion of UK homes have solar panels.
Ministers hope the subsidies will bring the UK into line with other countries which have a much better take-up rate.