The concept of a free, renewable and inexhaustible supply of electricity harvested from the sun is an ideal scenario toward which many governments and green activists are striving. They possibly perceive it as large arrays of photovoltaic cells situated on buildings or harvested from acres of solar farms. According to the Energy Savings Trust, the fastest growth in energy usage stems not from gas-guzzling cars or expanding jet travel, but from consumer electronic devices, such as mobile phones and MP3 players. The emphasis the consumer electronics vendors are putting on longevity of battery life adds credibility to the component manufacturers' claims. Yet we have been here before with integration of fuel cells into portable devices three years ago. But the integration of solar power is more likely to occur as the technology has overcome a significant barrier which fuel cells so far have not - a smaller footprint.