How to Calculate Azimuth Angle for Solar Panels

There’s a simple rule of thumb for finding the azimuth angle for solar panels:

Face them true south in the northern hemisphere and true north in the southern hemisphere.

But how do you find true south or true north? After all, compasses point towards magnetic north.

It’s actually quite easy. I’ll cover the free tools you can use to calculate the right solar panel azimuth angle for your location.

1. Solar Panel Azimuth Angle Calculator

Our solar panel azimuth angle calculator finds true south or true north based on your location and then tells you how to orient your panels in that direction using a compass.

Under the hood, it uses the World Magnetic Model to find your location’s magnetic declination and then adjusts your azimuth angle based on that.

Instructions

1. Go to the calculator.

2. Type in your location, such as your city or zip code.

3. Select your location from the search results.

4. Use a compass to orient your solar panels towards the resulting azimuth angle.

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2. True North Compass App

A standard compass shows magnetic north, but there are plenty of compass apps that can show true north.

I have an iPhone, so I’ll cover how to find true north using the iPhone’s default Compass app. (For Android users, you can download a compass app that shows true north.)

Instructions

1. Go to Settings > Compass.

2. Go to Location then select “While Using the App.” The app needs to know your location to calculate true north.

3. Go back to Compass settings then select “Use True North.”

4. Open the Compass app to see your true orientation. Now your compass app shows true north rather than magnetic north.

5. If you’re in the northern hemisphere, point your panels toward true south. If you’re in the southern hemisphere, point your panels toward true north.

3. NOAA Magnetic Declination Calculator

The National Oceanic and Atmospheric Administration (NOAA) has a magnetic declination calculator you can use to find true north.

Instructions

1. Go to the calculator.

2. Enter your location in the Location field and click “Get & Add Lat / Lon”. This adds your location’s latitude and longitude to the calculator. Alternatively, if you already know your coordinates, you can just type them into the Latitude and Longitude fields (in degrees, minutes, seconds).

3. Click “Calculate”.

4. Find your location’s magnetic declination in the results window. Your results are given in degrees, minutes, seconds which you can convert to a decimal.

5. Correct your compass by your magnetic declination to get true north. If magnetic declination is east or positive, it means magnetic north is east of true north. If it’s west or negative, it means magnetic north is west of true north. To correct, you need to adjust by the angle of magnetic declination in the opposite direction. For instance, in this example my magnetic declination is 7° 53′ E, or 7.87° E written as a decimal. This means magnetic north at my location is 7.87° east of true north. To find true north, I need to point my compass toward magnetic north and then adjust 7.87° west.

6. If you’re in the northern hemisphere, point your panels toward true south. If you’re in the southern hemisphere, point your panels toward true north.

4. NOAA Magnetic Declination Maps

NOAA also publishes magnetic declination maps you can use to find the optimal azimuth angle for your solar panels.

Here is a magnetic declination map of the United States:

And here is a magnetic declination map of the entire globe.

Note: Both of these maps were produced for 2020. Magnetic declination values for the current year will be slightly different.

Instructions

Let’s say you live in Los Angeles, California. Here’s how you’d use a magnetic declination map to find which direction to face your solar panels.

1. Locate the closest line to your location. I marked the spot where Los Angeles is on the map. Turns out there’s a line just north of it. (The lines on the maps are called isogonic lines, which are lines along the earth’s surface where magnetic declination values are constant.)

2. Find the magnetic declination value of the line. Positive values mean magnetic north lies east of true north. Negative values mean magnetic north lies west of true north. The line next to Los Angeles is 12°, meaning magnetic north is about 12° east of true north in Los Angeles.

3. Find true north by adjusting your compass for your location’s magnetic declination. If your magnetic declination is positive, true north is west of magnetic north by the degree of magnetic declination. If your magnetic declination is negative, true north is east of magnetic north by the degree of magnetic declination. Magnetic north in Los Angeles is 12° east of true north, so true north is 12° west of magnetic north. To find true north, I point my compass north, and then adjust 12° west.

4. If you live in the northern hemisphere, face your solar panels toward true south. If you live in the southern hemisphere, face your solar panels toward true north. Los Angeles is in the northern hemisphere, so I face my panels toward true south, which would be 12° east of magnetic south.

5. PVWatts

True south and true north slightly outperform magnetic south and magnetic north, but they aren’t always the best azimuth angles. Sometimes, local weather patterns can cause a location’s optimal azimuth angle to be slightly east or west of the true azimuth.

Using the National Renewable Energy Laboratory’s PVWatts Calculator, you can find your optimal azimuth angle that takes into account historical weather data.

Instructions

1. Go to PVWatts.

2. Enter your city or address in the search bar then click “Go”.

3. On the Solar Resource Data page, scroll down to the map and confirm that the calculator selected the right location. If it did, click “Go to system info.” If it didn’t, click “Change Location” at the top of the page and try again.

4. On the System Info page, experiment with different azimuth angles (in degrees clockwise from true north) until you find the value that generates the most electricity. Start by typing in a number, then click “Go to PVWatts results”. I entered “180” as my first azimuth angle.

5. Record the estimated system output. At an azimuth angle of 180° clockwise from true north, a solar power system at my location (with the default inputs) would generate an estimated 6,415 kWh per year.

6. Go back to the System Info page and adjust the azimuth angle up and down in increments of 1 until you find the angle(s) that generates the most solar energy at your location. After trying many different numbers, I found that 175-179° clockwise from true north are my optimal azimuth angles — any of them would generate an estimated 6,416 kWh per year.

7. Orient your panels toward your optimal azimuth angle using a true north compass app or magnetic declination calculator. To do so, find true north using one of the two methods described above and then adjust clockwise from true north by your azimuth angle.

As you can see from this example, the extra energy gleaned from this method can be minimal. But at least you can rest easy knowing you’re getting the most energy out of your solar system.

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Alex Beale
Alex Beale is the founder and owner of Footprint Hero. As a self-taught DIY solar enthusiast, Alex has spent 4 years producing educational solar content across YouTube, TikTok, Instagram, and the Footprint Hero blog. During that time, he's built Footprint Hero to over 7 million blog visits and 18 million YouTube views. He lives in Tennessee.