Global solar generation capacity increased by almost 30 gigawatts in 2011 The US is still the biggest investor in clean energy. It regained top spot from China last year according to global rankings. A Global rankings table, which was published in a report by the Pew Charitable Trusts, showed that US government invested more than $48bn (£30bn) in the sector, which was a significant increase from $34bn in 2010.
China slipped to second place last year the report mentioned, with the Communist nation only increasing its investments by $0.5bn to $45.5bn.
Overall worldwide financial investing in clean energy technologies hit a record $263bn, which was up 6.5% from 2010 levels.
The report, which is called ‘Who is winning the clean energy race’, showed that G20 nations accounted for 95% of the investment in the sector. However it must be noted that nuclear energy was not included in the data taken.  
The data, which was compiled by Bloomberg New Energy Finance, ranked the UK as seventh in the world, with $9.4bn of investment in 2011.
Over the course of last year, an extra 83.5 gigawatts (GW) was added to the world\'s clean energy generation capacity. This included almost 30GW of solar and 43GW of wind.
\"The sector continues to expand and is outpacing growth in the overall (global) economy. The sector reached its trillionth dollar of investment last year,\" Phyllis Cuttino, director of Pew\'s Clean Energy Program said.
\"We now have 565GW of installed (generation) capacity around the world. That outstrips nuclear installed capacity by 47%. So I think the facts fly in the face of those individuals who say this is a niche industry. This is a growing and maturing sector.\"
Cuttino stated that the market data showed that the US benefited in the short-term from attracting investments; however she cautioned that this pattern was unlikely to be sustained.
\"Investors rushed in to take advantage of expiring policies, such as tax incentives, loan guarantees, which expired at the end of 2011,\" Ms Cuttino told BBC News.
\"So when we look at the very rapid rate of growth in investment here in the US, it is hard to see how that could be maintained without the policy mechanism that spurred that growth. \"She suggested that there were signs that pointed towards a \"drop off\" in future clean energy investment as a result of \"policy uncertainty\".