Stealthy solar panel manufacturing startup Alta Devices announced today that it has produced solar panels that have broken previous efficiency rating records for solar panels.

Alta Devices said it was able to produce Gallium Arsenide solar panels that capture 28.2 percent of the light shining on the panel and convert it to electricity, up from a previous efficiency rating of 27.6 percent that the company produced last year. The last record for solar panel efficiency rating was 26.4 percent, according to results verified by the National Renewable Energy Laboratory.

Wafer-style solar panels have a theoretical efficiency rating of 33.5 percent, according to the company. Alta Devices appears to be developing solar panels that will eventually reach that efficiency rating. The company is one of several solar panel manufacturers that focus on wafer-style solar panels that operate best in clear days when the sun is shining directly on the panel.

Thin-film solar panels like those that First Solar manufacture do not have efficiency ratings as high as those types of solar panels. But they are able to perform better in diffuse light situations and in high-temperature environments, said First Solar’s Pam Hegarty. Those panels take up more space than crystalline solar panels and cost more to install, but can generate more electricity in non-optimal environments, she said.

“All things being equal, those systems have a higher conversion efficiency,” she said. “But when the sun is not at a 90 degree angle, thin-film solar cells absorb more of that light and has a broader energy curve than crystalline silicon panels.”

Alta Devices recently raised $72 million in its most recent round of funding despite still being in stealth mode. A job posting at the time indicated the company wanted to develop photovoltaic cells that are around 30 percent efficient and can generate 1 watt of electricity at a cost of 50 cents.

The Santa Clara, Calif.-based company plans to move a few minutes north to Sunnyvale, Calif., according to Green Tech Media. It has 55 employees and has filed for 35 patents, according to the job posting. The company also received a $3 million grant from the Department of Energy to develop low-cost and highly efficient photovoltaic cells.