What Direction Should Solar Panels Face? (And Why West Wins Sometimes)

Key Takeaways

• South wins on total kilowatt-hours in the northern hemisphere — the sun spends its day in the southern sky.
• West increasingly wins on dollars: late-afternoon production aligns with time-of-use peak rates and beats the noon glut under net billing.
• East/west faces give up a modest slice of annual output — typically on the order of 10–20% — which panel count can offset if the roof allows.
• Tilt near latitude is textbook-ideal, but almost everyone correctly just follows the roof; PVWatts prices the difference for your address in minutes.

Why south is the physics answer

From anywhere in the continental US, the sun's daily arc lives in the southern half of the sky — rising southeast-ish, peaking due south, setting southwest-ish, with the whole arc riding higher in summer. Panels facing true south intercept that arc most squarely for the most hours, which is why south has been the reflexive answer since residential solar began: it maximizes total annual kilowatt-hours from a fixed roof.

Note true south — the compass on your phone points magnetic south, which diverges from solar south by up to double digits of degrees depending on your longitude. Installers design to true azimuth; a DIY shed project should too.

Why west is the economics answer (sometimes)

Total kilowatt-hours stopped being the whole scoreboard the moment utilities started pricing hours differently:

• Time-of-use rates bill late afternoon and evening — when everyone's AC and ovens run — at multiples of midday rates. West-facing panels, which peak at 3–6pm, generate into exactly that expensive window; south-facing panels peak at noon, the cheap hour.
• Net billing (California-style) pays little for exports. A south array's noon surplus exports at pennies; a west array produces later, when the household is home consuming it at full retail value.

Under either regime, a west face can earn more per kilowatt-hour than a south face loses in volume — which is why utility programs in evening-peaked grids have at times explicitly favored westward panels. If your tariff prices hours flat and exports at retail, south remains unbeatable; if your tariff has a shape, your panels should consider having one too.

Directional; PVWatts models your exact azimuth trade-offs.

Tilt: the other half of aiming

Textbook optimum tilts panels near your latitude — Denver arrays at ~40°, Miami's at ~26° — squaring them to the year-round average sun. In practice, racking that fights the roof's pitch costs more than the few percent it recovers, so installers overwhelmingly lay panels flat to the roof plane and let PVWatts quantify the small forfeit. The two exceptions worth engineering: flat roofs, where ballasted racks add tilt cheaply (and due-south aim for free), and snow country, where steeper panels shed cover faster and catch the low winter sun — one reason serious off-grid builds in the north mount steep.

What to actually do with your roof

1. Inventory the faces. Note the azimuth and rough area of each unshaded roof plane — south-ish, west-ish, east-ish.
2. Learn your tariff's shape. Flat with retail exports → chase south and total volume. TOU or net billing → weight west and self-consumption.
3. Let PVWatts referee the splits. Model south-only against south+west against east+west for your address; the tool prices each layout's annual harvest in minutes.
4. Don't force the compass. A big clean west roof beats a shaded or slivered south one every time — orientation is a multiplier on the roof you have, not a veto over it.

South collects the most sunlight; the right direction collects the most value. In the growing share of America where those differ, the compass answer is now a tariff question wearing a hardware costume.

Keep reading: panels to power a house · per-panel daily output · sizing for 1,000 kWh.