Will solar speed up emerging cellphone revolution?

"I am self-employed. Sometimes people call me and they find my (cell) phone is off. I have been having that problem a lot due to battery charging. So when (Uganda Telecom) brought out the solar phones, since I got it, that very day, I have never had any problem with my phone," said Mawa, clutching the device.

It might not sound like much but for Mawa and millions of people in Africa and Asia, with no connection to electricity grids or unreliable and expensive power access, these little solar-powered gadgets are proving to be revolutionary.

Farmers can check market prices before deciding which crop seeds to sow, speak to buyers from their fields and get weather forecasts. And unlike with standard mobile phones, they don't have to worry about their phone battery losing power.

Solar cellphones could build on the economic advantages that mobile phones have already brought to far-flung regions of Africa and the Indian subcontinent, including price transparency and more accurate and timely information.

Mobile phone penetration in these regions has been held back by a lack of electricity: there is simply no way to charge a cellphone in many rural areas of developing countries.

An estimated 1.6 billion people have no access to electricity at all, while another 1 billion people have no electricity for much of the day, according to estimates by development groups.

Fortuitously, perhaps, most of these people live in sunny climates. And this is where solar mobile phones come in.

"If you look at the map of countries with low tele-density -- there is plenty of sunshine everywhere," says Rajiv Mehrotra, chairman of VNL, a company making solar-powered mobile network base stations in India.

Take Uganda as a case in point: Just eight percent of the country's 32 million plus population have electric grid access. Even when the grid is there, like where Mawa lives in Mulago, a poor suburb of Kampala, the power is costly and the service is intermittent.

"In our area, electricity is expensive so at six o'clock in the morning, we turn our power off until six in the evening," said Mawa, 29, sitting on a step outside his house.

Until solar cellphones were introduced, charging a phone in remote areas, off the electricity grid, entailed a bone-jarring journey to the nearest town, where the phone battery could be charged at kiosks run on generators for relatively hefty fees.

The journey might take all day and the battery charge fee might cost more than that day's lost wages.

MARKET PENETRATION

There are more than 3 billion people using mobile phones around the world and most of the next billion users will come from emerging markets, particularly in the countrysides of these markets.

"There is a significant opportunity within developing markets where there is limited access to grid electricity," said Windsor Holden, principal analyst at telecoms research firm Juniper Research.

The makers of solar cellphones such as Nokia, Samsung and ZTE see the rural poor in these emerging markets as their main customer base rather than carbon-conscious consumers in the West.

"People's need to communicate is so high. It's running miles ahead of the power grids expansions," says Anne Larilahti, head of environmentally sustainable business at network equipment maker Nokia Siemens Networks.

Across the ocean, in India's remote Orissa state, farmers living off the power grid are generating electricity with solar power which is making inroads in rural India and Bangladesh. For them, solar-powered cellphones are a natural extension.

The potential in rural India for cellphone makers and operators is huge. Consider this: India had nearly 500 million wireless users, and some 10 million new users are signing up each month. That doesn't count the millions in India's remote villages where electricity is rare or non-existent.