Google, Oak Investment and Idealab back eSolar to the tune of $130M

In the rapid rise of solar thermal power, a small handful of companies have grabbed the lion’s share of attention and funding: Ausra, Brightsource and Solel are the three most oft-heard names. Another company, eSolar, can now add its name to that shortlist, with one of the biggest cleantech venture fundings to date.

Notably, eSolar has plans to immediately funnel the money into construction projects that may see its plants going online ahead of its competitors’.

The solar thermal designs of all these companies involve using fields of mirrors to reflect and concentrate sunlight on contained water, which then boils and powers turbines. From that starting point everything can differ, from the size and shape of the mirrors to the type of receptacle containing the water and the location of the power plant.

ESolar’s trick is a minimalist design that uses small, flat mirrors in relatively modest deployments — the company is planning to build a series of plants producing 33 megawatts each, which is enough to power from 15,000 – 25,000 average Californian homes. Ausra, by contrast, is planning a 177MW plant in San Luis Obispo County, while Brightsource has a deal for five of about the same size.

Going smaller has several benefits for eSolar. The biggest is that the bureaucratic stumbling block of permitting is smoothed for plants under 50MW. Having smaller plants — they fit on about 160 acres of land — could also benefit eSolar by allowing it to nestle plants into areas that are closer to the regular transmission grid.

The size and speed with which they can be built means that eSolar could potentially have a plant up by the end of this year or early next. Most of its competitor’s earliest installations are scheduled for a year or so beyond that.

How far the $130 million investment will carry eSolar is another question. While the company boasts that it has a cheap manufacturing process and efficient designs, aided by software that intelligently aims the mirrors, building even small plants is still an expensive proposition. Despite the scale of Google.org (the search giant’s philanthropic arm) and Oak Investment Partners, eSolar will probably soon be shopping around for even larger amounts from banks and private equity.

Idealab, the third funder in the round, is also headed by eSolar’s chairman, Bill Gross. The company is based in Pasadena, Calif., and also took $10 million from Google.org in January.