Best Direction and Angle for Solar Panels (By Latitude)

Two variables control how much your array produces from a given number of panels: azimuth (the compass direction it faces) and tilt (the angle from horizontal). Here is what each is worth.

Direction: south wins on energy

In the northern hemisphere the sun tracks across the southern sky, so a true south array sees the most sun-hours at the best angles.

Approximate annual production relative to true south, for a typical US roof pitch:

Direction	Relative annual output
South	100%
Southeast / southwest	95–97%
East / west	80–85%
Northeast / northwest	65–75%
North	55–65%

Two practical notes. First, this is true south, not compass south — magnetic declination in the US ranges from roughly 20 degrees east in Washington state to 20 degrees west in Maine. Second, the penalty for being off-south is gentler than most people expect. Losing 15% on a west roof is often solved by adding two more panels, which costs far less than the roof-plane gymnastics people imagine.

When west beats south

Here is the part that surprises homeowners: the direction that produces the most energy is not always the direction that earns the most money.

Under a time-of-use rate plan, electricity in the late afternoon and early evening is worth two to three times as much as midday power. A south array peaks at solar noon, when rates are cheapest. A west array peaks at 3–5pm, right into the expensive window.

The same logic applies where export credits are low relative to retail rates — California’s NEM 3.0 being the headline case. There, generating at 4pm when you are actually using power beats generating at noon and exporting for a few cents.

So: if you are on, or heading toward, a time-of-use plan, a west or southwest array can beat south on bill savings even while producing 15% less energy. See time-of-use rates and solar for how to check your plan.

Tilt: your latitude, roughly

For maximum annual production, tilt at approximately your latitude:

• Southern US (25–33°N): about 30 degrees
• Middle US (34–40°N): about 35 degrees
• Northern US (41–48°N): about 40 degrees

A standard pitched roof is typically 18–35 degrees (a 4:12 to 8:12 pitch), which lands close enough to optimal that the difference is a few percent. Do not pay to correct it.

Season-shifting is a real option though:

• Steeper than latitude favours winter, when the sun is low. Useful if your bills peak in winter, or with poor net metering where winter self-consumption matters.
• Shallower than latitude favours summer, when the sun is high. Useful in cooling-dominated climates.

If your bill is driven by summer air conditioning, shallow-and-west is often the money-optimal combination even though it is not the energy-optimal one.

Flat roofs and ground mounts

This is where tilt becomes a genuine decision rather than a given.

On a flat roof, you can flush-mount at near-zero tilt or use tilt racking. Tilt racking gains you maybe 8–12% per panel — but it adds cost, adds wind uplift (which means ballast or more penetrations), and requires row spacing so front rows do not shade back rows. On a space-constrained roof, tilt racking often means fitting fewer panels, which cancels the gain. Flush mounting also means panels never self-clean from rain runoff, so soiling losses rise — see solar panel maintenance.

On a ground mount you have complete freedom, so use it: true south, latitude tilt, no compromise. That is one of the underrated advantages of ground mounting.

Shade beats both

Before optimising azimuth by two degrees, deal with shade. A single branch across one panel can drag down a whole string on a string inverter. Shading losses routinely dwarf the 15% you would gain by moving from west to south.

Ask your installer for a shade analysis — a proper one produces a Total Solar Resource Fraction (TSRF) per roof plane. Anything under about 75% deserves a conversation about trimming, microinverters or optimisers, or skipping that plane.

Practical guidance

1. Use the roof planes you have; do not rebuild the roof for solar.
2. Prefer south, then southwest, then west, then east. Skip north in most of the US.
3. Take the roof’s existing pitch unless it is nearly flat.
4. Split across two planes if that is what fits — microinverters or optimisers handle mixed orientations without penalty, and an east/west split actually flattens your production curve, which helps under time-of-use.
5. Fix shade first.
6. If you fall short of your target, add panels rather than chase perfect orientation.

Bottom line

South at latitude tilt is the textbook answer, and it is right for most homes on standard net metering. If you are on time-of-use rates or a low-export-credit tariff, run the numbers on west — you may find that the “worse” roof plane is worth more per year.

Educational estimates only. Production varies with local climate, shading and equipment. Ask installers for a modelled estimate for your specific roof.