It's a price performance drive system for your sunseeker project or rgv robotics.
Is it really suitable for home solar tracking?
Emerson Photovoltaic has shown a Typical Control Techniques drives and geared stepping motors used for intelligent solar tracking which used a servo motor with nrv worm gear.
For home use, a Nema23 stepper motor system is more reasonable price.

New arrival:
Nema34 66mm stepper motor rated current 3A and holding torque 2.5N.m
RV30 10:1 ratio worm gear
Material for worm reducer stepper motor gearbox RV30:
Worm wheel: Nodular cast iron and bronze
Worm shaft: 20Cr steel.The hardness of surface is 56-62HRC with carbonized layer 0.3-0.5mm
Housing: Aluminum with oven painting
NEMA23 11mm bore worm gear output shaft

NEMA34 14mm bore output shaft