First of all, you should know the latitude of Jiangmen. I take the latitude of Guangzhou as the latitude of Jiangmen.

Guangzhou is located on the tropic of cancer, 22.26 degrees north latitude, which is 23 degrees for convenience of calculation.

During the summer solstice, the maximum height angle of the sun is 90 degrees, so the inclination angle of the heating plate is 0 degrees.

In winter solstice, the minimum height angle of the sun is 90-23-23=44 degrees, and the inclination angle of the heating plate is 90-44=46 degrees.

0-46 degrees It is suggested that the inclination angle is about 20 degrees, facing south.