The Vatican has inaugurated 2,400 photovoltaic solar panels installed on the roof of the 'Nervi Hall' where popes hold general audiences and concerts are performed.
The system, which went live on Wednesday after weeks of testing, will provide 300 kilowatt hours of clean energy a year for the audience hall and surrounding buildings.
This will be used for lighting, heat and air conditioning.
"At a time of growing sensibility towards the problems of the environment, the Vatican has shown that it is taking action, " the Vatican said in a statement.
"Pope Benedict XVI has given ever-growing attention to the most urgent ecological problems affecting the planet.
"He has particularly stressed the importance of exploring alternative energy sources," the statement added.
The 1.2 million euro system was devised by two German companies - SolarWorld and SMA Solar Technology - which donated it to Pope Benedict XVI.
Officials said the Vatican's famous skyline - especially the dome of St. Peter's will be unspoilt by the solar panels.
The 5,000 square metre roof of the Nervi Hall is wavy and the solar panels are virtually invisible from the ground. The panels are the same size as the tiles of the hall's roof.
The Vatican plans to install enough renewable energy sources to generate 20 percent of its needs by 2020 - a goal that is in line with European Union targets, officials said.
The solar panels will allow the Vatican to cut its emissions of CO2 - one of the main greenhouse gasses - by about 225 tonnes and save the equivalent of 80 tonnes of oil annually.
At Wednesday's unveiling ceremony, Italian Nobel prize winner for physics, Carlo Rubbia, described the Vatican's solar panels as "a very courageous initiative."
The sun has 100,000 times the energy produced by the earth's traditional energy sources, he pointed out.
No responsibility or liability shall attach itself to either myself or to the blogspot ‘Clerical Whispers’ for any or all of the articles placed here.
The placing of an article hereupon does not necessarily imply that I agree or accept the contents of the article as being necessarily factual in theology, dogma or otherwise.