Solar panels in the northern hemisphere should face south — specifically, true south rather than magnetic south. A south-facing orientation maximizes the panel’s exposure to sunlight as the sun moves from east to west across the southern sky throughout the day. This orientation captures peak irradiance at solar noon and provides the most symmetrical morning-to-afternoon production, yielding the highest annual energy output for any given roof pitch.
That said, “due south is best” is the starting point — this guide covers all the nuances that determine the optimal direction for your specific situation.
Why South-Facing Is Optimal in the Northern Hemisphere
The sun rises in the east and sets in the west, but in the northern hemisphere, it never rises due east or sets due west except at the equinoxes — it’s always somewhere in the southeastern to southwestern arc. At solar noon (when the sun is highest in the sky), the sun is due south of any location in the northern hemisphere. A south-facing panel captures the sun’s highest-intensity, most direct irradiance at solar noon, and benefits from symmetrical morning and afternoon exposure.
True south vs magnetic south: Solar panel orientation should reference true south (also called geographic south), not magnetic south as indicated on a compass. Magnetic declination — the angular difference between true north and magnetic north — varies across the US from approximately +25° (Cascades) to −20° (Deep South). In Seattle, magnetic south is approximately 16° east of true south. Use the NOAA magnetic declination calculator (ngdc.noaa.gov/geomag) or let your installer’s design software handle it automatically with GPS coordinates.
Production by Direction: The Numbers
Annual production relative to optimal due-south orientation for a panel at latitude-appropriate tilt (NREL PVWatts modeling, averaged across US locations):
| Direction Faced | Annual Production vs South |
|---|---|
| South (180°) | 100% — Optimal |
| South-Southeast or South-Southwest (150° or 210°) | 97–99% |
| Southeast or Southwest (120° or 240°) | 88–94% |
| East or West (90° or 270°) | 78–88% |
| North-Northeast or North-Northwest (30° or 330°) | 50–65% |
| North (0°) | 45–60% |
The production curve is relatively flat within 45° of south — a panel facing anywhere between SSE (southeast-of-south) and SSW loses only 1–12% compared to due south. The drop-off becomes steeper beyond 60° from south, and north-facing panels suffer severe production penalties.
When East or West-Facing Makes Sense
While south maximizes annual energy, east-facing or west-facing panels serve specific purposes:
East-facing panels: Produce their peak output in the morning hours (7 a.m. – noon). Useful for households with high morning electricity consumption (morning cooking, electric car charging before commuting, early-shift workers). Morning peak production also avoids the afternoon-heat efficiency penalty common in hot climates — east-facing panels are cooler in the morning, producing at slightly higher efficiency than south-facing panels later in the hot afternoon.
West-facing panels: Produce their peak output in the late afternoon (noon – 7 p.m.). Under California NEM 3.0 and in other markets with time-of-use (TOU) electricity pricing, the highest-value electricity is late afternoon and evening (4–9 p.m., “super peak” periods). A west-facing array that peaks at 4–6 p.m. produces electricity when it’s most valuable under TOU pricing, potentially generating better financial returns than a south-facing array despite producing 12–20% fewer total kWh annually.
East-west split arrays: Many flat-roof commercial and industrial installations use an east-west split — half the panels facing east, half facing west, both at 5–10° tilt. This “fills” the production curve for more hours per day at reduced peak, increases panel density per roof area, reduces inverter clipping at midday peak, and broadens the system’s useful generation window. Production is approximately 15–20% less than a south-facing optimally tilted system, but the higher GCR (ground coverage ratio) can make it the better choice for flat roofs with limited area.
What to Do When Your Roof Doesn’t Face South
Many homes have roofs that don’t face south — due to the lot orientation, street layout, or architectural style. Options:
Use available south-facing sections: Many roofs have multiple faces. If you have a south-facing section, even a smaller one, prioritize it for solar installation. A 5 kW south-facing array on a small section may outperform an 8 kW array on a predominantly north-facing main roof.
East or west faces are viable: A panel facing east or west produces 80–88% of a south-facing panel’s output. In many cases, this is an excellent choice — not every homeowner can get due south, and 80%+ efficiency is still financially compelling in markets with high electricity rates.
Ground-mount systems: If your roof orientation is poor (primarily north-facing with no viable south or east-west sections), a ground-mounted solar array facing south at the optimal tilt is a cost-effective alternative. Ground mounts can be installed in any direction and at any tilt angle. They cost slightly more than roof mounts ($0.20–0.50/watt additional), but the orientation flexibility fully compensates for this in most cases.
Tilt adjustment for non-south roofs: For southeast or southwest-facing roofs, slightly increasing tilt angle (above the latitude-optimal angle) can partially offset the directional penalty. This is a small effect but worth modeling in design software. For east or west-facing panels, a tilt of 15–20° (lower than latitude-optimal) can also increase daily energy production compared to steeper tilts, because it captures morning and afternoon light more effectively than steep tilts that favor the midday sun.
How Installers Determine the Best Direction for Your Home
Professional solar designers evaluate panel direction as part of the site assessment and system design process:
Satellite imagery analysis: Design software (Aurora Solar, Helioscope) creates a 3D roof model from satellite and aerial imagery, automatically measuring each roof face’s azimuth and tilt. The software then models the sun’s position at every hour of the year at your specific location and calculates the production for each roof face.
Shading analysis: A slightly off-south roof face with no shading often outperforms a south-facing face with afternoon tree shading. The shading analysis — accounting for trees, chimneys, neighboring buildings, and skylights — is often more important than a few degrees of azimuth deviation. Shading and direction are optimized together, not independently.
TOU optimization: If you’re in a TOU market, the designer considers which roof face direction produces electricity when it’s most valuable — not just which produces the most total kWh. A west-facing roof with afternoon TOU peak pricing may have better economics than south-facing with flat pricing.
Frequently Asked Questions
Should solar panels face east or south?
South-facing panels produce approximately 10–15% more annual energy than east-facing panels of the same wattage in most US locations. For maximum annual energy production, south is the better choice. However, east-facing panels are a good option when your roof faces east and a south-facing installation is not practical, or if your household has high morning electricity consumption. East-facing panels produce 85–90% of south-facing output in most US locations — still highly financially viable.
What direction is worst for solar panels?
North-facing is the worst orientation for solar panels in the northern hemisphere. Panels facing north (0° azimuth) receive sun only indirectly — the sun is always in the southern sky, so a north-facing panel “looks away” from the sun for most of its productive hours. North-facing panels produce approximately 45–60% of south-facing output in the US. If your only available roof space is north-facing, a ground-mount system facing south is usually a better investment.
Is it OK if solar panels don’t face south?
Yes, for east, west, southeast, and southwest orientations — the production penalty is modest (12–22% compared to due south) and the financial case for solar remains strong in markets with electricity rates above 12–15¢/kWh. The only genuinely problematic orientation is due north, which is rarely installed in the northern hemisphere. Your installer should model production for your actual roof orientation and confirm the economics before proceeding.
Do solar panels work on a north-facing roof?
They generate electricity but at significantly reduced output — approximately 45–60% of south-facing production. In most US markets, this makes north-facing installations economically marginal: longer payback periods, lower lifetime savings. Options for north-facing roofs include ground mounting, using available east or west sections of the roof, or a carport solar installation that can face south regardless of roof orientation.
Why do some solar panels face east instead of south?
East-facing installations are chosen for several reasons: the roof only faces east (no viable south-facing sections); the homeowner has high morning electricity consumption; the east-facing roof is unshaded while south-facing sections are shaded; or under some TOU pricing structures, early morning electricity is more valuable than midday electricity. East-facing systems produce approximately 85–90% of south-facing output and remain financially attractive in most markets.
Summing Up
Solar panels in the northern hemisphere should ideally face due south (180° true south) for maximum annual energy production. East or west-facing panels produce 80–88% of south-facing output and remain financially viable in most markets with decent electricity rates. Southeast and southwest-facing panels lose only 6–12% compared to south-facing. North-facing installations should be avoided or replaced with ground mounts facing south. Professional solar design software models the optimal direction for your specific roof, shading environment, and utility pricing — accounting for all variables simultaneously rather than treating direction in isolation.
To find out which direction and configuration would work best on your specific roof — call (855) 427-0058 for a free site assessment. Local solar installers model production for your exact orientation and location at no cost.
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