Solar Nerd articles about: Azimuth

If you live in the Northern Hemisphere, the sun rises in the east, spends a bunch of time in the southern sky, and then sets in the west. Some plants have developed an ability, called heliotropism, to track the sun as it makes this daily trip across the sky. A young sunflower will point east in the morning, track the sun until it sets in the west, and then reorient themselves so they’re ready for the sun again in the morning.

If you live in the Northern hemisphere, solar panels will receive the most sunlight if they face south. (This is reversed in the Southern hemisphere, so if you live in Australia the preferred direction is north). If you’re a homeowner interested in solar, you might not have this option: maybe the south-facing part of your roof is interrupted by vents, skylights or gables, or is shaded by trees. West is usually the next best option (which generates electricity during the evening peak) followed by east.

If you’re a solar homeowner, of course you want your solar panels to generate as much electricity as possible. One of the ways to do this is by tilting them at the optimal angle so they capture the maximum amount of sunlight year-round. So what is the best tilt angle for solar panels in the United States? Short answer: a tilt of approximately 25° to 35° will work best for locations in the US.

To generate the maximum electricity from your solar panels, you want them pointed south (if you live in Northern Hemisphere), but sometimes you don’t have much of a choice. Most homeowners mount their solar panels on their roof and consequently only have a couple orientations to choose from. (This is also known as azimuth, where 0° means pointing north and 180° is south.) Solar panels will work if you face them east: on average, east-facing solar panels will generate about 80% as much electricity as they would if pointed directly south.

If you’re one of those people who never pays attention to their utility bill, you might assume that there’s just one price you pay for electricity. Electricity is priced by the kilowatt-hour (kWh), and if you didn’t know, one kWh is equal to using 1,000 watts (a kilowatt) of electricity for one hour. If you left your hair dryer running on high for 32 minutes, you’d use about one kWh.

If you’re a homeowner planning to install solar panels, you’ll either be placing the array on your roof, which is facing in a fixed direction, or you’ll be using a ground mount that gives you some flexibility about where to point them. Especially if you live in a city, you might not have much choice about the direction to face your panels. For example, you might have trees shading one side of your home.