The Renewable Energy Country Attractiveness Indices study, which ranks 40 countries, shows China and Germany holding their second and third-placed spot with the UK moving up one place to fourth.
The report outlines the policies and initiatives that determine a country's position in the rankings.
US President Obama’s Climate Action Plan, unveiled in May, set out a variety of clean energy and emissions reduction measures. This included an additional 10GW of renewable energy projects on public lands by 2020 and dates for the first two leasing auctions for the offshore sector were set.
China signed a climate change pact with the US in June setting out five actions for reducing emissions.
Energy is a key issue in Germany's September’s election. Most political parties favour a reduction in support for renewables to reduce electricity prices but the lack of clear policy statements is destabilising the sector, said the report.
The UK jumps to fourth place thanks to revised electricity consumption growth projections and an increase in the number of new build asset finance deals.
Australia fell two places to sixth in the index, reflecting the impact of political in-fighting over Australia’s decarbonisation agenda.
France took eighth place from India, thanks to a slightly improved macroeconomic outlook and higher electricity demand forecasts. A final decision is also on the horizon regarding the eligibility of France’s wind feed-in tariff, uncertainty over which significantly hindered the sector’s progress in recent years.