It is not an easy time to be a cleantech venture capitalist. Still a hardened group of investors presses on. A handful of these determined GPs talk about what keeps them going.

We take a look at the clean technology companies that have raised the most venture funding in the last few years. Overall, it is not light and pleasant reading.

BrightSource Energy said it raised more than $80 million of additional equity financing, brings its total equity financing to more than $615 million. Alstom and VantagePoint Capital Partners lead the round with DFJ, CalSTRS, DBL Investors, Goldman Sachs, Chevron Technology Ventures and BP Ventures and others joining.

Cleantech is out of favor. Sure, Nuventix just raised another $6.9 million, and Accel this week put $6.7 million into Vigilent, with the help of several angels. But even as startups such as BrightSource Energy appear to press ahead with IPOs, Enphase Energy this morning cut the expected price of its offering to between $6 and $7 a share.

For venture-backed companies in registration to go public, August is not shaping up as a promising month. While it remains to be seen whether the worst of the market downturn is behind us or ahead, the debt ceiling imbroglio and S&P downgrade of U.S. debt have already had a chilling effect on IPOs. Three venture-backed [...]

Enphase Energy joined the list of top cleantech companies testing the IPO waters this year by filing for an IPO on Wednesday The company said in a S-1 registration statement submitted to the Securities and Exchange Commission that it plans to raise $100 million. A successful offering will benefit six venture investors with substantial stakes [...]

Solar titan First Solar sent dark clouds over the cleantech markets last week when quarterly earnings fell by almost a third. Yesterday, skies cleared when JA Solar’s latest financial report beat Wall Street’s estimates with a nearly 90% rise in quarterly net income, even though Energy Conversion Devices conceded its third quarter sales tumbled 70%. [...]

Cleantech pundits like to point out that the rest of the world is cleaning America’s clock in green technology.

But this isn’t entirely true if you look at venture investing. Especially if you look at the recently completed first quarter, when U.S. venture capitalists accounted for 79% of the global capital dispersed to cleantech startups.

It was the highest percentage since 2002, according to the Cleantech Group.

In our previous cleantech slideshows, we’ve covered the quarter’s solid rebound. First-quarter cleantech investment dollars were up 13% from a year ago and 52% from the fourth quarter to $2.57 billion, according to the Cleantech Group.

While deal volume lagged, it was still up 18% from a year ago. The quarter’s 159 deals proved to be the lowest total since mid-2009 and fell 19% from the fourth quarter’s 189.

Solar continued to be the driving force behind cleantech investing in the first quarter as venture capitalists shifted dollars to more mature, later stage companies.

The quarter saw investors worldwide pour $2.57 billion into 159 companies, a 13% increase in dollars from last year, according to the Cleantech Group. The majority of the money – 93% – went to follow-on rounds.

Surprisingly, this more cautious environment was fertile ground for solar deals. Solar startups attracted $641 million, or 24% of total dollars, as several big deals led the way. The next closest industry sector was transportation, with less than half the committed dollars.

The global downturn eventually put the skids on the ability of cleantech firms to raise cash. General partners found it hard to pitch LPs for new money when they could show little in the way of returns from past funds. Or so goes the prevailing wisdom. Stop here! Maybe this storyline isn’t as accurate as [...]