The cost of a panel starts at 50, 000 euros, but with a tax break from the regional government and a guaranteed annual income there is a long waiting list of willing buyers.

BBC: Wind turbines

Nor could they get the annual 5% increase in income that is guaranteed by the arrangement.

ECONOMIST: Japan

RIFs are managed to achieve targeted annual income returns, often in the range of 3-12%, though income is not guaranteed.

FORBES: Top Retirement Investments For 2011