Flush-mounted panels sit at exactly your roof angle. The optimal year-round tilt is roughly your latitude × 0.76. This calculator shows how much output you give up by mounting flush instead of at the ideal angle.
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| Pitch | Angle | Slope % | Multiplier | Hip / valley | Rafter per 12" run |
|---|---|---|---|---|---|
| 0.25/12 | 1.19° | 2.08% | 1.0002 | 1.4144 | 12.00" |
| 0.5/12 | 2.39° | 4.17% | 1.0009 | 1.4148 | 12.01" |
| 1/12 | 4.76° | 8.33% | 1.0035 | 1.4167 | 12.04" |
| 1.5/12 | 7.13° | 12.50% | 1.0078 | 1.4197 | 12.09" |
| 2/12 | 9.46° | 16.67% | 1.0138 | 1.4240 | 12.17" |
| 2.5/12 | 11.77° | 20.83% | 1.0215 | 1.4295 | 12.26" |
| 3/12 | 14.04° | 25.00% | 1.0308 | 1.4361 | 12.37" |
| 3.5/12 | 16.26° | 29.17% | 1.0417 | 1.4440 | 12.50" |
| 4/12 | 18.43° | 33.33% | 1.0541 | 1.4530 | 12.65" |
| 4.5/12 | 20.56° | 37.50% | 1.0680 | 1.4631 | 12.82" |
| 5/12 | 22.62° | 41.67% | 1.0833 | 1.4743 | 13.00" |
| 5.5/12 | 24.62° | 45.83% | 1.1000 | 1.4866 | 13.20" |
| 6/12 | 26.57° | 50.00% | 1.1180 | 1.5000 | 13.42" |
| 6.5/12 | 28.44° | 54.17% | 1.1373 | 1.5144 | 13.65" |
| 7/12 | 30.26° | 58.33% | 1.1577 | 1.5298 | 13.89" |
| 7.5/12 | 32.01° | 62.50% | 1.1792 | 1.5462 | 14.15" |
| 8/12 | 33.69° | 66.67% | 1.2019 | 1.5635 | 14.42" |
| 8.5/12 | 35.31° | 70.83% | 1.2255 | 1.5817 | 14.71" |
| 9/12 | 36.87° | 75.00% | 1.2500 | 1.6008 | 15.00" |
| 9.5/12 | 38.37° | 79.17% | 1.2754 | 1.6207 | 15.31" |
| 10/12 | 39.81° | 83.33% | 1.3017 | 1.6415 | 15.62" |
| 11/12 | 42.51° | 91.67% | 1.3566 | 1.6853 | 16.28" |
| 12/12 | 45.00° | 100.00% | 1.4142 | 1.7321 | 16.97" |
| 13/12 | 47.29° | 108.33% | 1.4743 | 1.7815 | 17.69" |
| 14/12 | 49.40° | 116.67% | 1.5366 | 1.8333 | 18.44" |
| 15/12 | 51.34° | 125.00% | 1.6008 | 1.8875 | 19.21" |
| 16/12 | 53.13° | 133.33% | 1.6667 | 1.9437 | 20.00" |
| 18/12 | 56.31° | 150.00% | 1.8028 | 2.0616 | 21.63" |
| 20/12 | 59.04° | 166.67% | 1.9437 | 2.1858 | 23.32" |
| 24/12 | 63.43° | 200.00% | 2.2361 | 2.4495 | 26.83" |
Is my roof pitch the same as my panel tilt?
If the panels are mounted flush to the roof, yes, they are the same angle. A 6/12 pitch means a 26.6 degree tilt, not a 6 degree tilt. Tilt frames decouple the two at the cost of money, wind load and appearance.
Is it worth adding tilt frames?
Rarely on a residential pitched roof. The yield curve is almost flat near the optimum, so a fifteen degree mismatch costs only a few percent. Shading and compass direction usually matter far more than tilt.
Which direction should panels face?
True south in the Northern Hemisphere and true north in the Southern. Being up to thirty degrees off costs less than five percent.
