The company's three-year contract expires at the end of December. "We will not be extending our partnership," a spokeswoman for Bosch subsidiary Rexroth told Financial Times Deutschland on Tuesday, saying the company was refocusing its priorities.
Desertec is looking to make use of solar energy from Northern Africa and the Middle East in the decades to come. "The aim is to supply around 15 percent of Europe’s electricity by 2050," the Desertec Foundation's website said.
Yet despite gaining backing from big firms, progress on the project has been markedly slower than expected.
Bosch's announcement came shortly after German engineering heavyweight Siemens, which is abandoning its solar power business altogether, said it would not stay on as a shareholder in the Desertec Industrial Initiative (DII).
DII confirmed Bosch's decision, telling the FTD it "regretted the move." Bosch Rexroth was one of the initiative's associated partners.
But DII said the number of companies associated with the initiative was set to rise by the year's end.
Bosch Rexroth's involvement in Desertec is focused on technology exchange and expert workshops. The company produces substructures for solar power farms, which allow units to be positioned toward the sun. But like other sectors of the company, Bosch Rexroth has felt the impact of slumping sales in Europe - prompting it to review and refocus its activities.