E.ON-backed fuel cell system producer Bloom Energy has reportedly filed for an initial public offering, one likely to value it at less than its previous $2.9bn valuation.

Bloom Energy, the US-based fuel cell system provider that counts energy utility E.ON as an investor, has confidentially filed for an initial public offering, the Wall Street Journal has reported.

Founded in 2001 as Ion Energy, Bloom manufactures oxide cell energy storage systems that can be installed on-site to produce energy for large buildings by converting gas to electricity.

The company was valued at $2.9bn as of a $150m series G round in 2011 but it will be unlikely to…