With winter temperatures plummeting across Europe a Serbian maths professor has come up with a novel, not to mention economical, way of heating his house for free - by using empty beer cans to create a solar power heating system.

Darko Milicevic has turned the empties into solar panels which look set to save him as much as £500 a year on heating bills, which is almost twice the average salary in Serbia.

So far his invention for the beer can solar panels on the roof and radiators has cost the 39-year-old just £50.

Genius: Darko Milicevic realised his empty beer cans could save him hundreds of pounds a year by turning them into solar panels

Savings: The 39-year-old replaced the copper in a solar panel with beer cans - a far cheaper option

Somewhat unsurprisingly, Mr Milicevic, from Paracin, in central Serbia, came up with the idea after drinking a few of his favourite beers.

He told MailOnline: 'I was thinking about how to make my own heating system free of charge, because everyone wants to make their lives easier during this [economic] crisis.

'Then I realised I could use beer cans instead of buying copper tubes.

'I drink beer anyway and it was fun inventing something alternative.'

Using 44 cans, Mr Milicevic, who teaches maths at the local high school, constructed his experimental 3.5ft-long beer can panel as a prototype.

Boring 22 holes into two planks of wood, he them balanced the cans on top of each other before drilling little ventilation holes into them and painting them black.

'The system is similar as in all solar panels,' he explained.

'I placed it on the southern wall of my house. The sun rays heat the air in the cans and the hot air naturally goes up through the cans and into the house, heating the space there.'

Proud: The simple but genius idea came to Milicevic while he enjoyed a few cans of his favourite beer as he pondered how to save money on heating his home in Paracin, central Serbia

Simplicity: The maths teacher explained the sun rays heat the air in the cans - which have been placed in a panel and attached to an outside wall - and the hot air naturally goes up through the cans and into the house

Mr Milicevic added that he also painted the cans black to get more energy from the sun rays.

'The most expensive item was plexiglass to protect the panel. I also used styrofoam to isolate it, so not to lose any heat,' he said.

Taking to Facebook to show off his invention, he explained that on New Year's Eve, when the temperature outside dropped to a freezing minus five Celsius in Parcin, his beer can panel heated his water boiler to 51.8 degrees.

There is a catch, however.

'If there is no sun at all, it does not work. But even if the outside temperatures are very low and there is sun, it works.'

Now with his water heating bills having been reduced to zero, he says he will create more panels from empty beer cans to heat the entire house.

Eco-friendly: The hot air coming into the house, warming the water in his boiler. On New Year's Eve, when the outside temperature was minus-five, his water heated up to 51.8 degrees

Every little detail: For maximum effectiveness, he has painted the 44 beer cans black

He said: 'One metre of this panel is not enough to heat the whole house. But if I put up 10 or 20 square-metre panels it would make it.

'The whole thing has cost around £50. I don't count beers in that because I would drink them anyway.

'But it could save me around £500 a year.'

He added: 'It would of course function equally as well with copper tubes, but this way it is much cheaper.

Cheap: The panel cost £50 - but he doesn't include the price of the beer as he 'would have drunk it anyway'

Since beginning his experiment a few weeks ago, the mathematician has been flooded with calls from locals wanting to know how they too can make savings.

He said: 'Many people have phoned me in recent days as during the financial crisis many are trying to find more economic solutions.