This week, Google announced an $80 million equity investment in six solar photovoltaic projects being developed by Recurrent Energy in Arizona and California.

The deal marks the company's 14th investment since it started eyeing project-level opportunities around the world in late 2009 -- amounting to nearly $1 billion since that time.

Before Google's big renewable power play, which started in 2006 with a 1.3-megawatt solar installation on its Mountain View headquarters, corporate investment in clean energy was largely funneled through renewable energy credits (RECs). The purchasing of RECs, which arguably doesn't do much to bring new renewable generation on-line, was criticized by many who saw it as corporate greenwashing, not true investment.

Over the last few years, however, with Google helping to set an example, direct investment in renewable energy projects among large corporations has exploded.

A recent report from the Solar Energy Industries Association found that 25 of America's largest companies had cumulatively deployed 3,380 megawatts of onsite solar projects. From 2012 to 2013, corporate projects expanded by more than 40 percent.

The same trend is taking place in offsite projects as well. According to the corporate sustainability advocacy group Ceres, nearly one-quarter of the companies on the Fortune 100 list have set targets for renewable energy procurement, with a large number signing power purchase agreements.

It would be a stretch to give Google credit for starting this trend. The move away from RECs has come from a combination of improving project economics, strong local policy, and a corporate push to find new investment opportunities. But the company has been on the front end of the transition, racking up one of the most impressive clean energy portfolios.

"Slowly but surely, Google has become a major player in U.S. solar project finance, and one of the few corporate investors to have made significant, repeated investments in solar projects and portfolios. Google is likely also the only corporate investor outside the energy sector to have played in both the utility-scale market and the distributed generation market," said Shayle Kann, vice president of GTM Research, reacting to the company's latest solar announcement.

How did Google do it? Here is a timeline of how the tech giant moved from bits and bytes to electrons and therms. The list is not exhaustive, but represents the most important highlights over the last seven years.

2006: Google begins the largest corporate solar PV project ever built

In the fall of 2006, Google partnered with EI Solutions (a developer later purchased by Suntech) to build a 1.6-megawatt system on its Mountain View campus. Back then, a system of that size was still a big deal within the solar industry. Having it attached to Google's name made it an even bigger deal.

Summer 2007: Google announces $10 million vehicle-to-grid program

On the same day it officially hooked its 1.6-megawatt solar system to the grid, Google made its first push into the electric vehicle sector, announcing plans to help commercialize vehicle-to-grid technologies under its RechargeIT initiative. Over the following year, it made venture investments in Aptera Motors and ActaCell, and tested charging methods on its campus. It also partnered with the Rocky Mountain Institute to identify technology and market breakthroughs needed for EVs.

Fall 2007: Google rolls out RE<C initiative

When Google announced its RE<C initiative (meaning renewable energy less than coal), it blew the doors off any other corporate sustainability effort. Other large companies had started developing strategies to green their supply chains, but Google was trying something totally different: investing directly in groundbreaking technologies that could completely transform the energy sector.

Over the next few years, Google poured millions into concentrating solar power (CSP) developers eSolar and BrightSource, enhanced geothermal (EGS) developer AltaRock, and hydrothermal drilling company Potter Drilling. It attempted to leverage its software and engineering skills to improve project design and lower the cost of CSP and EGS.

Fall 2009: Google plans for project-level investments

At an event at Google's headquarters, Dan Reicher, Google's then-director of clean energy initiatives, said the company would start financing renewable power plants. Although Google failed to give details at that time, the company backed up its promise, investing hundreds of millions in projects over the proceeding years.

February 2010: Google gets permission to sell electricity like a utility

Before scaling up its project financing efforts, Google first received approval from the Federal Energy Regulatory Commission to sell and buy electricity like a utility. The move gave Google more flexibility in how it managed its onsite generation, structured its power purchase agreements, and harnessed electricity for its data centers.

2011: Google announces an end to RE<C, citing cost drops in solar PV

After four years of experimentation in CSP and EGS, Google finally decided to end its ambitious RE<C initiative. Some in the press wrongly reported that Google had "abandoned" renewable energy. Instead, the company cited the steady cost drops in photovoltaics, saying that it would rather focus on project financing rather than R&D.

Shortly after announcing the end to RE<C, Google dropped more than $350 million into funds for solar service companies Clean Power Finance and SolarCity. And in the subsequent years, it has scaled its project financing from $580 million to more than $1 billion.

Spring 2010 to present: Google expands its investment bonanza

Since arming itself with the ability to act like a utility and phasing out its R&D efforts, Google has supported fourteen projects worth more than 2 gigawatts of capacity.

GTM's Herman Trabish assembled a list of some of the top plays Google made in one year alone:

$75 million in a fund operated by Clean Power Finance (CPF) that will finance 3,000 rooftop solar home installations

in a fund operated by Clean Power Finance (CPF) that will finance 3,000 rooftop solar home installations $280 million in a fund operated by SolarCity that will extend that company’s lease program to some 8,000 new system owners

in a fund operated by SolarCity that will extend that company’s lease program to some 8,000 new system owners $168 million in BrightSource Energy’s Mojave Desert utility-scale CSP solar power tower facility that will supply 392 megawatts of electricity to California power suppliers SCE and PG&E (following an initial $10 million investment in the company itself)

in BrightSource Energy’s Mojave Desert utility-scale CSP solar power tower facility that will supply 392 megawatts of electricity to California power suppliers SCE and PG&E (following an initial $10 million investment in the company itself) 37.5 percent early equity stake in the Atlantic Wind Connection, a transmission backbone that will ultimately cost approximately $5 billion and deliver 7,000 megawatts of offshore wind-generated electricity from a 2,000-megawatt-capacity, high-voltage, direct-current, 250-mile transmission path between southern Virginia and northern New Jersey

in the Atlantic Wind Connection, a transmission backbone that will ultimately cost approximately $5 billion and deliver 7,000 megawatts of offshore wind-generated electricity from a 2,000-megawatt-capacity, high-voltage, direct-current, 250-mile transmission path between southern Virginia and northern New Jersey $157 million in 270 megawatts of wind being built at the Alta Wind Center in Southern California’s Tehachapi Mountains

in 270 megawatts of wind being built at the Alta Wind Center in Southern California’s Tehachapi Mountains $100 million in the 845-megawatt Shepherd’s Flat project in Oregon, the biggest on-land wind farm in the world

in the 845-megawatt Shepherd’s Flat project in Oregon, the biggest on-land wind farm in the world $38.8 million in two North Dakota wind farms with a total capacity of 169.5 megawatts, the first production tax credit deal done after the 2008 economic crash

in two North Dakota wind farms with a total capacity of 169.5 megawatts, the first production tax credit deal done after the 2008 economic crash €3.5 million (~$5 million) for 49 percent of an 18.65-megawatt PV solar installation in Brandenburg, Germany

This list will likely get quite a bit longer in the coming years. As Kojo Ako-Asare, head of corporate finance for Google, wrote on the company's blog yesterday, the tech giant has every intention of becoming a renewable energy giant.

"You’d think the thrill might wear off this whole renewable energy investing thing after a while. Nope -- we’re still as into it as ever," wrote Ako-Asare.