Is It Worth Adjusting Your Solar Panel Angle Seasonally?
Our previous articles looked at fixed-angle installations where the panels stay in one position all year. But what if you could change the tilt twice a year? Four times? We ran the comparison for six cities to find out how much extra energy you'd actually get.
The three scenarios
We calculated the weather-adjusted optimal angle for each city under three setups:
- Fixed - one angle, all year, never touch it
- 2 adjustments - change tilt in April (summer position) and October (winter position)
- 4 adjustments - change tilt every quarter (Jan, Apr, Jul, Oct)
For each period, we optimize both tilt and azimuth independently using 2025 weather data. This is the maximum theoretical gain from seasonal adjustment at each location.
The results
| City | Fixed (kWh/m²) | 2x/year | Gain | 4x/year | Gain |
|---|---|---|---|---|---|
| Phoenix | 2,233 | 2,338 | +4.7% | 2,345 | +5.0% |
| Sydney | 1,930 | 2,018 | +4.5% | 2,020 | +4.7% |
| New York | 1,713 | 1,784 | +4.1% | 1,787 | +4.3% |
| San Francisco | 2,012 | 2,089 | +3.8% | 2,091 | +3.9% |
| London | 1,406 | 1,455 | +3.5% | 1,458 | +3.7% |
| Seattle | 1,502 | 1,545 | +2.9% | 1,547 | +3.0% |
Two things jump out.
First, seasonal adjustment is worth 3-5% extra generation depending on the city. Phoenix benefits most at 4.7% with just two changes per year. That's on top of any gains from weather-adjusted angle optimization, so the two stack.
Second, going from 2 adjustments to 4 adds almost nothing. The gap between 2x and 4x is 0.1-0.3% for every city in the table. Twice a year captures nearly all the benefit. Quarterly isn't worth the extra effort.
Why the tilt changes so much
To understand why this works, look at how the optimal tilt swings between summer and winter:
| City | Fixed tilt | Summer tilt | Winter tilt | Swing |
|---|---|---|---|---|
| Phoenix | 30° | 13° | 51° | 38° |
| New York | 36° | 18° | 56° | 38° |
| San Francisco | 35° | 20° | 55° | 35° |
| Sydney* | 33° | 54° | 14° | 40° |
*Sydney's seasons are reversed. "Summer" here is Apr-Sep (their winter), "Winter" is Oct-Mar (their summer).
The swings are huge. Phoenix goes from nearly flat (13°) in summer when the sun is almost directly overhead, to a steep 51° in winter when the sun tracks low across the southern sky. The fixed angle of 30° is a compromise that's never actually optimal in either season.
New York has an even wider swing: 18° to 56°. In summer the sun is high and you want a shallow tilt. In winter it's low and you want your panels pointing almost like a wall toward the horizon.
What about the azimuth?
Tilt is where most of the seasonal gain comes from. The azimuth changes are smaller and less consistent:
| City | Fixed azimuth | Summer azimuth | Winter azimuth |
|---|---|---|---|
| Phoenix | 180° S | 180° S | 190° SSW |
| New York | 195° SSW | 180° S | 200° SSW |
| San Francisco | 215° SW | 225° SW | 205° SSW |
San Francisco's azimuth actually shifts more toward the west in summer (225°) when the morning fog is worst, and back toward south in winter (205°) when fog is less of an issue. But the change is small compared to the tilt swing, and for most people adjusting tilt alone is enough.
Putting it in dollars
Using the same 8 kW US system baseline from our savings article:
| City | 2x/year gain | US avg rate | California rate |
|---|---|---|---|
| Phoenix | +4.7% | $2,120 | $3,710 |
| New York | +4.1% | $1,850 | - |
| San Francisco | +3.8% | - | $3,200 |
| London | +3.5% | ~£1,400 at UK rates | |
A Phoenix homeowner adjusting twice a year saves about $2,120 over 25 years at average US electricity prices, or $3,710 at California rates. That's real money, but you have to decide if climbing on the roof twice a year for 25 years is worth it to you.
The honest assessment
Seasonal adjustment gives you 3-5% more energy. Twice a year captures almost all of it. Going to four times adds basically nothing.
Whether it's worth doing depends on your setup:
- Ground-mounted panels with adjustable tilt brackets: do it. It takes 10 minutes twice a year and pays for itself many times over.
- Rooftop panels you can safely access: probably worth it if you're comfortable on the roof. The dollar value adds up over 25 years.
- Rooftop panels that require a ladder and safety equipment: probably not. The cost of a professional visit twice a year would eat the savings. Spend the effort on getting the fixed angle right instead.
- Solar trackers: they do this automatically throughout the day and capture even more than seasonal adjustment. But they cost money and have moving parts that can fail.
For most residential rooftop installations, the best move is to optimize your fixed angle using weather-adjusted data rather than the textbook formula. That's a one-time decision that gets you 1-3% extra for free. Seasonal adjustment on top of that is a nice bonus if your setup makes it practical.
Find your seasonal angles
Our calculator lets you optimize for any combination of months. Run it for summer and winter separately to see your specific tilt swing.
Calculate Your Optimal AngleMethodology
Same setup as our other analyses: pvlib for irradiance modeling, 2025 weather data from Open-Meteo, brute-force optimization over all tilt/azimuth combinations. For seasonal scenarios, we optimize each period independently and sum the results. The "2x/year" split is Apr-Sep and Oct-Mar. The "4x/year" split is quarterly. Dollar calculations use the same assumptions from our savings article: 8 kW system, 25 years, 0.5% annual degradation.