EVO Magazine:

"The battery will power an electric motor that will deliver around 100 kW power (approximately 130bhp).

An extra 130bhp over the IC engine's 380bhp means total power output will reach 500bhp, that means an even stronger acceleration, and higher speeds due to the availability of instant torque. Lessons have been learned from the infamous Group B cars, and despite the jump in power, the FIA will regulate how this power can be used. The teams will have control over battery boost deployment and benefit from it on particular parts of a stage, that will likely be predefined by the organisers. This is to make sure the competition remains equal and more importantly, safe."