Southern California is sunny, the French Riviera is sunny, but NASA says the middle of the Pacific Ocean and the Sahara Desert in Niger are the sunniest places -- and the information could be worth money.
America's space exploration agency has located the world's sunniest spots by studying maps compiled by U.S. and European satellites.
The maps can also gauge solar energy at every other spot on the planet and already have been used to help businesses site solar panels in Morocco, for instance, or send text messages to tell sunbathers in Italy to put on more cream.
"We are trying to link up observations of the Earth to benefit society," said Jose Achache, head of the 72-nation Group on Earth Observations, which seeks practical spinoffs from scientific data ranging from deep-ocean probes to satellites.
GEO member states held ministerial talks Nov. 30 in Cape Town, South Africa, to review a 10-year project launched in 2005 that aims to join the dots among research in areas such as climate change, health, agriculture and energy.
From satellite data collected over 22 years, the National Aeronautics and Space Administration said the sun blazes most fiercely on a patch of the Pacific on the Equator south of Hawaii and east of the island nation of Kiribati.
More practically for solar generation, the Sahara region soaks up the most energy on land, with the sunniest spot in southeast Niger, where a ruined fort at Agadem bakes amid sand dunes.
For some reason, there are fewer clouds there than elsewhere in the Sahara, said Paul Stackhouse, a senior scientist at NASA's Langley Research Center.
The area got a searing average of 6.78 kilowatt-hours of solar energy per square meter a day from 1983 to 2005 -- roughly the amount of electricity used by a typical U.S. home to heat water each day. The patch in the Pacific got 6.92 kilowatt hours.
The maps could help guide billions of dollars in solar investments for a world worried by climate change -- widely blamed on burning fossil fuels -- that could mean more floods, droughts, heat waves and rising seas.
Satellite pictures also could help site offshore wind farms. Wind speeds can be inferred from wave heights and direction. Farmers might be able to pick new crops or estimate fertilizer demand by knowing more about how much solar energy is reaching their land.
Using satellite data for Morocco, Portuguese company Net Plan worked out how many solar photovoltaic panels were needed to power a remote relay station for phone signals. It worked, and a costly backup of diesel generators was removed a year ago. "We're looking forward to install more units like this," said Net Plan executive Iolanda Sousa.
Among possibilities in Niger, the government is planning to award oil exploration permits for the Agadem block, which was explored by Exxon Mobil and Malaysia's Petronas until the license lapsed in 2006.
Anyone wanting to generate solar energy in Agadem -- for instance to provide electricity for a workers' camp -- would in theory need fewer solar panels there than anywhere else.
The world's environment ministers met in Bali, Indonesia, this month to launch talks on a long-term pact to fight climate change, partly by shifting to renewable energy sources such as solar.
Among other uses of solar data, a Canadian school in northern Nunavut territory worked out that it was worth putting solar panels on the wall after receiving help from Canada's publicly run RETScreen International, which gives advice on solar energy.
And Swiss firm Enecolo monitors output from solar panels by checking the amount of energy reaching a spot as measured by satellites -- if the panels generate less electricity than expected, then the problem might be dust or a loose wire.
"In some parts of Africa it could be economically interesting to use solar power rather than connect to a grid because of the lack of infrastructure," said Thierry Ranchin of the Ecole des Mines de Paris in France, which leads the solar project with NASA.
"If you want to bring electricity to a small village in Africa, it's often easier to do it with a stand-alone system than a grid with power lines," he said.
In Italy, a firm called Flyby monitors levels of ultraviolet radiation, which can cause skin cancer. If critical levels are reached, the monitors send out alerts by mobile phone to advise people to cover up.
"In the developed world, we have good surface solar measurements. When you go elsewhere, the data is much sparser. That's where the satellites can help," said Richard Eckman, manager of NASA's Langley program.
"Our goal is to find more practical applications of NASA-derived satellite operations across a whole range, such as energy or agricultural efficiency," he said.