The sun supplies only a tiny fraction -- less than one tenth of 1 percent -- of mankind's energy needs. But its supporters believe a solar era may be dawning, boosted by western funding to combat oil "addiction" and climate change.
Governments from Japan to Germany and the United States are helping the public wean themselves off fossil fuels.
An average German household, for example, can earn over 2,000 euros ($2,860) a year from subsidies to install solar panels -- double their electricity bill -- and pay off all costs within 10 years and earn a pure profit for a further 10.
But there are few handouts in developing nations where it could be argued solar power is more relevant -- in sunnier countries where many people have no electricity at all.
A scientific body which groups academies worldwide -- the InterAcademy Council -- said last week efforts to curb climate change must target vast numbers of people who lack basic energy.
"It's sad that 1.6 billion people live without electricity and two to three billion use energy in a primitive way very damaging to health," said Professor Steven Chu, a Nobel laureate physicist based at the University of California, Berkeley, and co-chair of the report for the Dutch-based body.
LOW INCOME
Low incomes and low subsidies, if any, can make clean energy a hard sell in developing countries.
In the Indian state of Karnataka private firms, backed by state government subsidies, have over the last 3-5 years been pushing solar power for households in towns and cities, including giving discounts on power bills if solar is installed.
The picture is very different for off-grid rural Indian communities which until now were dependent on kerosene, or paraffin, lamps for lighting, having no electricity access.
"Kerosene is quite heavily subsidised but has limited availability in some rural areas, which has helped solar PV (photovoltaic) sales," said J.P. Painuly, senior energy planner at the Denmark-based Risoe National Laboratory.
"There are some solar PV programmes that provide an extremely limited capital subsidy. It's not at a scale that makes it viable. Solar PV is still really expensive... more expensive than kerosene."
