Your winter sun
The short version
"Sun hours" means hours of strong, overhead-strength sun. Size solar for your darkest month, not the yearly average, and winter won't catch you out.
Where will your panels be? Pick whichever's easiest.
The whole country, in its darkest month
The yellower the square, the more winter sun. The Northwest and the Great Lakes get about a third of what the desert Southwest does, so the same home needs far more panels there.
AK0.5
ME2.5
WI2.4
VT1.8
NH2.4
WA1.8
ID2.4
MT2.5
ND2.6
MN2.3
IL2.5
MI1.9
NY2.4
MA2.7
OR1.9
NV4.4
WY3.2
SD3.1
IA3.0
IN2.4
OH2.0
PA2.5
NJ2.8
CT2.6
RI2.6
CA4.1
UT3.2
CO4.3
NE3.3
MO3.2
KY2.8
WV2.5
VA3.4
MD2.9
DE3.0
AZ4.9
NM5.0
KS3.6
AR3.5
TN3.1
NC3.7
SC3.8
DC3.2
OK3.7
LA3.7
MS3.5
AL3.5
GA3.7
HI5.0
TX4.0
FL4.5
Go deeper: why the darkest month
- Summer sun can be double winter sun. Size for the average and your batteries run dry in December.
- Northern and cloudy places (the Northwest, the Great Lakes, New England) have the darkest winters.
- These numbers are planning estimates for your region. Your exact roof or site can differ with shade and tilt.