In the end, the distinctive curved mirrors of Sopogy’s concentrating solar power technology could not compete with standard photovoltaic panels for the cost-effective production of electricity.

Honolulu-based Sopogy quietly slipped into insolvency in March after running into a number of obstacles, including plunging prices for PV panels. Sopogy had preliminary agreements to sell its concentrating solar power collectors to developers of solar energy projects but lost the contracts when the companies switched to lower-cost PV panels.

Sopogy wasn’t the only casualty from the worldwide glut in PV panels that hit the market about five years ago. Hoku Corp., a local company that was building a polysilicon production plant in Idaho, filed for bankruptcy in July after many of its customers canceled their orders for polysilicon, the primary component in PV panels. The Hoku closure followed the bankruptcies of dozens of PV panel makers in the U.S., Europe and Asia.

Sopogy, founded in 2002 by local entrepreneur Darren Kimura, had success selling its technology to commercial customers around the world who used the steam and superheated water generated by the solar collectors for a variety of industrial applications, including tuna canning, seawater desalination, crude oil extraction and air conditioning. Kimura left Sopogy in March 2013.

Several Sopogy executives and board members who were at the company when it closed declined to be interviewed for this story.

Sopogy began moving into the field of power generation with a pilot project called Holaniku at Keahole Point that went online in 2009 at the Natural Energy Laboratory of Hawaii on the Kona Coast. Holaniku is operated by Keahole Solar Power, which was spun off from Sopogy in 2007.

The facility was designed so that most of its 2-megawatt generating capacity would be used to provide steam and industrial hot water to companies located at NELHA, with excess heat being sent to turbines to generate electricity, according to Kimura.

Although the electrical generation portion of Holaniku was rated at 500 kilowatts, it never operated at full capacity, according to Hawaiian Electric Co. HECO’s Hawaii island subsidiary had signed a power purchase agreement to buy "as-available energy" from the Holaniku facility.

Despite the issues at Holaniku, Keahole Solar Power moved forward with a much larger 5-megawatt project in West Oahu that was designed with Sopogy’s "MicroCSP" solar collectors as the power source.

Sopogy’s technology uses parabolic mirrors made of polished aluminum to collect sunlight and focus it on a tube carrying a heat-transfer fluid, usually mineral oil. The mineral oil is heated to about 500 degrees Fahrenheit and pumped through an evaporator where the heat is used to vaporize a liquid refrigerant. The vapors turn a turbine that generates electricity. The mineral oil is then sent back to the mirrors to be reheated, and the vaporized refrigerant is cooled and returned to a liquid state to be used again.

Keahole Solar Power in March 2012 signed a PPA with HECO for the West Oahu project to be built on 43 acres of land to be leased from the Department of Hawaiian Home Lands. The project, called Kalaeloa Solar One, was to feature nearly 1,000 Sopogy MicroCSP collectors.

But with PV panel prices falling, and the loss of Treasury Department cash incentive programs for solar projects, it became clear that MicroCSP collectors were not going to pencil out for Kalaeloa Solar One, Kimura said. KSP switched technologies and instead opted for PV panels for the project.

Sopogy was dealt an even larger blow when a Chinese company backed out of a memorandum of understanding to use Sopogy’s technology in a 200-megawatt energy project in China.

Sopogy was one of several Hawaii startups that benefited from a now-defunct state program known as Act 221 that provided tax breaks to investors who put money into local tech companies. An official at the Hawaii Department of Taxation said the office does not compile data linking the amount of credit claimed to individual qualified companies. However, Kimura said many of Sopogy’s larger investors, companies such as Mitsui & Co., SunEdison, Sempra Energy and 3M, did not have a Hawaii tax liability and therefore were not eligible to claim the credit.

Kimura also said that while Sopogy was authorized by the state Legislature to issue up to $45 million in special-purpose revenue bonds, it never exercised that option.