The project will cost an estimated Sh250 billion ($2.5 billion).
Local firms did not meet the financial threshold set by the government.
The facility, which will constitute 3,300 solar panels, will generate 1,256MWh a year.
The government is building 4,120km of roads countrywide.
Sections of the highway are damaged, with broken drainage covers.
Thika Road completion has also seen several shopping malls being rolled out along the route.
The road is inspired by the N1 highway that runs from Cape Town to Harare.
Construction of the Tazara Flyover commenced in 2016 and was completed in 29 months.
The facility is expected to boost power supply to the port to 132Kv from 11Kv.
More than 60 road projects countrywide have stalled due to lack of funds.