The Solu Khola Hydropower Project is of the Run-Of-River (ROR) type.
The project comprises an ungated 15m high and 31.80 m long concrete weir with a horizontal floor stilling basin built across the Solu river. The weir crest is located at elevation 1262 m a.s.l. A concrete intake is located on the left bank of the Solu river, formed by 3 orifices equipped with intake gates of 4.0 m x 2.0 m each. A gravel trap 5.0 x 5.0 m is provided behind the intake.
Three underground concrete desilting basins (L x H x W = 85.0 m x 9.0 m x 5m), achieve a trap efficiency of 90% for particles larger than 0.15mm and include a S4 flushing system for cleaning of the basins.
A 4500 m long partially concrete lined headrace tunnel (Inlet to Valve Chamber), D-shape (section 4.3 m x 4.5 m) and a 1850 m long steel penstock pipe (2.5 to 2.1 m diameter, including drop shafts and horizontal underground stretches) convey the water to the powerhouse located at the right bank of Dudh Koshi River at Maiku Besi. The powerhouse, housing 3 Pelton turbines is located about 1 km upstream of the suspension bridge across the Dudh Koshi River.
A 375.0 m long inclined surge tunnel (D-shape 4.0 m x 4.0 m) is provided to reduce hydraulic transients in the pressure waterways. Between the surge tunnel and the penstock, a valve chamber equipped with a safety shut-off butterfly valve is provided.
The project also includes 4 construction adits.