Peak Sun Hours by US State (NREL Average)
Average peak sun hours per day by US state (NREL geographic average) — the divisor for solar array sizing. Design for the worst month for year-round off-grid.
| State | Peak Sun Hours | Notes |
|---|---|---|
| Arizona (AZ) | 6.5 h/day | Annual average — design for the worst month if year-round off-grid. |
| New Mexico (NM) | 6.2 h/day | Annual average — design for the worst month if year-round off-grid. |
| Nevada (NV) | 6.0 h/day | Annual average — design for the worst month if year-round off-grid. |
| California (CA) | 5.5 h/day | Annual average — design for the worst month if year-round off-grid. |
| Colorado (CO) | 5.5 h/day | Annual average — design for the worst month if year-round off-grid. |
| Texas (TX) | 5.2 h/day | Annual average — design for the worst month if year-round off-grid. |
| Florida (FL) | 5.3 h/day | Annual average — design for the worst month if year-round off-grid. |
| Georgia (GA) | 5.0 h/day | Annual average — design for the worst month if year-round off-grid. |
| North Carolina (NC) | 4.7 h/day | Annual average — design for the worst month if year-round off-grid. |
| Illinois (IL) | 4.2 h/day | Annual average — design for the worst month if year-round off-grid. |
| New York (NY) | 4.0 h/day | Annual average — design for the worst month if year-round off-grid. |
| Ohio (OH) | 4.0 h/day | Annual average — design for the worst month if year-round off-grid. |
| Michigan (MI) | 3.9 h/day | Annual average — design for the worst month if year-round off-grid. |
| Washington (WA) | 3.7 h/day | Annual average — design for the worst month if year-round off-grid. |
| Oregon (OR) | 3.8 h/day | Annual average — design for the worst month if year-round off-grid. |
Sources: NEC Chapter 9 Table 8 (conductor resistance), NEC 310.16 (ampacity), NEC Chapter 9 Tables 1/4/5 (conduit areas & THHN), ASTM B258 (AWG geometry), NREL (peak sun hours) · All sources