Historically, the advice for finding the best angle for solar panels has been to set your tilt angle equal to your latitude.
Using latitude is a good rule of thumb. But we can also get slightly better solar panel angle estimates using free online tools.
Let's dive right in.
Calculate the Best Solar Panel Angle for Your Location
If you don't want to bother with all the technical details, you can just use our solar panel tilt angle calculator to calculate the best solar panel angle for your location or zip code.
- This calculator is based on a pair of mathematical formulas published in a 2018 research paper on optimal PV tilt angles
- According to an analysis I conducted, the tilt angles derived from these formulas generate on average 0.71% more power over the course of a year than setting your tilt angle equal to your latitude
What's the Best Angle for Solar Panels?
The most common answer to this question is to set the angle of your solar panels equal to your latitude. So, if your latitude is 30°, you'd set your solar panel tilt angle to 30° from horizontal.
I was curious how accurate this rule of thumb is, so I ran an analysis comparing the solar panel angles derived from latitude to 2 alternative methods:
- A pair of formulas published in a 2018 research paper
- Optimal tilt angles provided by the Global Solar Atlas
I found that, on average, using the tilt angles derived from the research paper's formulas generated an estimated 0.71% more power (in kWh per year) than using latitude. The tilt angles provided by the Atlas outperformed latitude by 0.56% on average.
So, using latitude is a great rule of thumb. But it's not the optimal tilt angle for solar panels. And, nowadays, free online tools make it easy to calculate a solar panel angle that will slightly outperform latitude.
Let's take a look at how to use 3 of these tools:
1. Our Solar Panel Tilt Angle Calculator
Because the research paper's formulas offer a slight improvement over latitude, a friend and I decided to code a free solar panel angle calculator that uses the formulas to calculate the optimal angle for your location.
Here's how to use it.
1. Go to our solar panel angle calculator.
2. Enter a location such as your city, address, or zip code. For example, I typed "Houston" in the box.
3. Select your location from the search results. For this example, I selected "Houston, TX, USA".
4. Get your results. Once you select your location, the calculator automatically calculates your optimal solar panel angle. According to our calculator, the best angle for solar panels in Houston is 26.5° from horizontal.
5. Scroll down to get your optimal tilt angles by season and by month. Our calculator also calculates your best solar panel angles by season and by month, in case you're interested in adjusting the angle of your panels throughout the year.
Note: I've also made a free spreadsheet version of this calculator. Feel free to make your own copy and use it in Excel or Google Sheets.
2. Global Solar Atlas
The Global Solar Atlas is a free interactive map provided by the World Bank. It has solar data, including optimal tilt angle, for nearly every location in the world.
Here's how to use it to find the best solar angle for your location.
1. Go to the Global Solar Atlas.
2. Click on your location on the map. For this example, I clicked on New York City. When you click on your location, a list of solar info pops up in the Site Info panel.
3. Find your location's "Optimum tilt of PV modules". There you will see 2 numbers. For my location, I see the numbers 35 and 180. The first number is the optimal tilt angle for your solar panels. This means my optimal tilt angle is 35° from horizontal. The second number is my optimal azimuth angle -- the direction I should face my solar panels -- expressed in degrees clockwise from north. This means my location's optimal azimuth angle is 180° clockwise from north, i.e. due south.
The Global Solar Atlas uses its own dataset to estimate optimal tilt angles, so its recommended tilt angles will be slightly different than the values given by our solar angle calculator and other solar calculators such as PVWatts. Also, it does not provide seasonal or monthly adjustments.
PVWatts is a free solar calculator built by the National Renewable Energy Laboratory. It's less user-friendly than the first 2 options, but it can give you the best estimate of your location's optimal solar panel angle.
Here's how to use it to find the best angle for your solar panels:
1. Go to PVWatts.
2. Enter your location in the search bar then click "Go." For this example I just typed in "Denver, CO".
3. On the Solar Resource Data page, scroll down to the map to confirm that PVWatts picked the right location. If it didn't, hit the back button and enter a more specific location.
4. Once you've confirmed the location is correct, scroll up and click "Go to System Info".
5. Enter a tilt angle in the "Tilt (deg)" field and then click "Go to PVWatts results". Denver is at about 40° latitude, so I'll use 40 as my starting value. For all the other inputs, such as DC System Size and System Losses, you can just leave those as their default values.
6. Record the system's expected power output at that tilt angle. At 40° tilt, my system's expected power output is 6,496kWh per year.
7. Go back to the System Info page and experiment with different tilt angles until you find the angle that maximizes power output. After trying a number of different angles, I found that 32° and 33° are the optimal tilt angles for a solar power system in Denver. Either one will maximize the system's annual power output.
PVWatts also breaks down estimated power output by month. So, if you wanted to optimize your seasonal or monthly tilt angles, you can experiment even further until you find the tilt angle that optimizes power output for a specific month or season.
Best Solar Panel Angle by Zip Code
Here's a list of the optimal solar panel tilt angles for 50 of the most populated zip codes in the United States.
Full list: Best Solar Panel Angle by Zip Code
|City||State||Zip Code||Best Year-Round Solar Panel Angle||Best Summer Solar Panel Angle||Best Winter Solar Panel Angle|
|New York City||NY||10025||31.9°||16.9°||46.9°|
If you don't see your zip code on this list, you can check out our full list of over 800 zip codes, which I've linked to above this table. Or input your zip code into the solar panel angle calculator at the top of this page.
What's the Best Direction for Solar Panels?
The best direction for solar panels is true south in the northern hemisphere and true north in the southern hemisphere. The direction you face your solar panels is also called their azimuth angle.
However, true south and true north are different than magnetic south and magnetic north. The difference between them is called magnetic declination, which varies by location as well as over time due to the moving of the earth's magnetic poles.
So, if you use a standard compass to orient your solar panels, their direction will be slightly off. You need to use a compass app that shows true north, or account for your location's current magnetic declination.
The good news is that I've also coded a free solar panel azimuth angle calculator that takes into account your location's current magnetic declination to give you your optimal solar panel direction. Give it a spin!