"Investment decisions for both developers and manufacturers need to be made a long time in advance and it's key that they get reassurance and understanding of how the market will allow generators of all sizes to produce and sell power, " said Renewable UK's director of policy Dr Gordon Edge.

BBC: Energy bill to boost cleaner energy production

During his visit, Karzai sought support and reassurance from Mr. Bush, who in turn wants Karzai's government to exert and extend its power.

NPR: Afghan President Meets Bush at Camp David