I have new PowerTap P1 dual sided pedals, a new Wahoo Kickr Snap and view Zwift on my plain HD flat screen TV through an Apple Lightning to HDMI cable that connects my phone to the TV.
Zwift is set up so that it reads power from my left P1 pedal, the Kickr is set as controllable trainer, HR is read through a Wahoo HR monitor and cadence is read through the right P1 pedal.
Also, to capture additional metrics not yet available on Zwift, I use my Wahoo Elemnt when riding on Zwift. The Elemnt reads power through the right P1 pedal, cadence through the left P1 pedal and HR through the Wahoo HR monitor. I do not connect the Kickr to the Elemnt. All are connected via Bluetooth.
Cadence and HR data are identical between the Elemnt and Zwift. However, power is rarely close and most times Zwift indicates 15 watts to 25 watts higher than the Elemnt. Both the Elemnt and Zwift are set to 3 second wattage measurement. I calibrate the P1 pedals before every ride and complete a spin down on the Kickr before every ride.
What can I adjust to close the power measurement gap?