Data In this chart is from a Davis Vantage Pro weather instrument. The solar sensor receives direct sun from around March 20th until October 20th. From October 20th until the tall trees to the south lose their leaves, the tree shadows significantly reduce solar energy from 1000-1400 hrs.  Then from late Nov. to late Jan. the sun is so low that the trunks and large limbs shadow the solar sensor so much that the solar sensor readings are not of much use.