Renewable power developer Powerhouse Energy Group PLC (LON:PHE) flagged hold-ups in testing its gasification waste-to-energy system, although it did not forecast major problems.
Powerhouse said there had been scheduling delays in finalising the testing programme for its newly designed PHE G3 UHt system.
The Shipley, West Yorkshire-based group completed parts testing on time, but the whole system was not yet fully functional, it said.
It has identified and resolved a few minor technical issues but said it had yet to demonstrate scheduling of final stress testing and other issues.
The group added in a statement: "Based upon the success of component testing to date, short-term testing of the overall system, and repeated cycling of the high-temperature unit, it is not expected any substantive technical issues will arise during the final testing."
Powerhouse expects to start final system testing in April. "The company will update the market upon the completion of final testing," it said.
Shares fell 0.02p, or 4.5%, to 0.52p in mid-morning London trading.