The growth of the renewable energy industry is often measured by capacity. How much power can be produced is central to our understanding of a changing world and shifting needs.

But as kilowatts turn into megawatts and megawatts turn into gigawatts, perhaps a better measure is a more human one. How many people are living healthier, more productive lives, especially in developing nations? This usually doesn’t fit neatly into a chart, and it’s often so anecdotal that it’s hard to put a face on.

Sometimes simple numbers can tell a story that is off the grid and under the radar. The most recent is an impressive milestone announced last week that Bangladesh has surpassed one million homes powered by solar energy.

"It's the fastest expansion of solar energy anywhere in the world,” Nazmul Haq of the state-run Infrastructure Development Company, which finances clean energy projects, told Agence-France Press. "We crossed the 1 million threshold more than 18 months ahead of schedule (and) we have set a new target to cross 2.5 million by 2014."

Bangladesh is the eighth most populous nation in the world with about 164 million residents. Two out of every three residents are involved in farming, poverty rates are high and energy -- who has it and who wants it -- is a big deal. According to AFP, 60 percent of those in Bangladesh live in homes not connected to the grid.

On the flipside, it’s also a developing nation, one that has made recent economic strides, and one that shows promise if the standard of living is increased across the country. Those who do have stable power are more connected and better able to recognize and seek out opportunities that will improve their living conditions.

In 2009, a reporter for the Brunei Times spoke to a mother of four whose husband and son worked abroad while she raised a family in rural Pritomoddi. The 40-watt solar installation on the roof of her homes has done more than power four light bulbs, a television and her cell phone. It has connected her to her family and the world at large.

"Life has become much easier now," said Kulsum Begum. “Whenever I need something, I call my husband or son on the cellphone. I am so happy now.”

The rise in solar development has been remarkable in Bangladesh, which had only 5,000 homes powered by the sun as recently as 2002. Since then, small-scale systems have been installed in a very large way, mostly in rural areas dependent on kerosene.

A World Bank report released earlier this year shows how increasing standards of living can have an exponential impact on development. According to the report: “the propensity to install solar home systems is very responsive to income, with a 1-percent increase in per capita income increasing the probability of installing solar home systems by 12 percent.”

In other words, those in rural Bangladesh need solar power, they see the benefits of having it and they are willing to pay for it once they can afford it.

A 2010 World Bank report, meanwhile, focused on energy poverty, and found that “58 percent of rural households in Bangladesh are energy poor, compared with 45 percent that are income poor. ... Reducing energy poverty helps reduce income poverty as well.”

While the Bangladesh success story may not show up on a list of nations with the highest growth in installed capacity, it may be laying the groundwork for an emerging market.