Which Side of the Roof Should Solar Panels Be On

The placement of solar panels on a roof significantly affects system performance, cost, and aesthetics. This article explains roof orientation, pitch, shading, structural factors, and alternatives to help homeowners choose the optimal roof side for solar panels. Key factors include orientation, tilt, shading, and local climate.

Roof Side	Typical Performance	Best Regions
South	Highest Year-Round Output	Most Of U.S.
West	Higher Afternoon Output, Good For Peak Rates	Areas With High Afternoon Demand
East	Morning Production, Slightly Less Energy	Cooler Climates, Morning Loads
North	Lowest Output, Often Not Recommended	Limited Use; Consider Tilt Or Ground Mount

Roof Orientation And Solar Production

Roof orientation describes the compass direction the roof surface faces. In the Northern Hemisphere, south-facing roofs receive the most consistent solar irradiance across the year, maximizing annual energy production compared to east, west, or north orientations.

East- and west-facing roofs can still produce substantial energy. West-facing arrays often yield higher afternoon production, which can match peak utility rates in many U.S. regions. East-facing arrays favor morning loads but usually produce slightly less daily energy than west.

Best Roof Sides By U.S. Region

Regional climate, seasonal sun arcs, and electric load patterns influence which roof side is optimal. South orientation is generally best nationwide for maximizing annual kWh.

In the Southwest and Sun Belt, long sunny afternoons make west-facing panels especially attractive for matching high evening demand. In the Northeast and Pacific Northwest, south-facing systems still deliver the best year-round yields because of lower sun angles in winter.

Roof Pitch, Tilt, And Solar Efficiency

Roof pitch (angle) affects the effective tilt of PV modules. The optimal tilt for maximum annual energy generally equals the site’s latitude, but roofs rarely match exactly. A steeper roof in northern states can improve winter gains, while flatter roofs favor summer production.

Racking systems allow adjustment of module tilt within structural limits. If roof pitch is far from ideal, installers can use tilt mounts or ground-mounted systems to reach more optimal angles and improve output by several percent.

Shading, Obstructions, And Micro-Siting

Shading from trees, chimneys, vents, or neighboring buildings can dramatically reduce energy output. Choosing the roof side with the least shading across peak sun hours is often more important than nominal orientation.

Micro-siting uses shaded area analysis, solar path diagrams, and site-specific modeling to identify the best roof sections. Modern string inverters and power optimizers mitigate partial shading but do not replace the value of an unshaded orientation.

Roof Materials, Age, And Structural Considerations

Not all roofs are equally suitable for solar. Asphalt shingle, metal, and tile roofs can all host PV, but installers must consider roof age, load capacity, and attachment methods.

Older roofs that will need replacement within a few years should be re-roofed before installation. Structural engineers may be needed for weak rafters or complex roofing. Permits and local codes dictate attachment hardware, especially for tile and slate.

Electrical And Utility Considerations

Panel placement affects wiring length, conduit runs, and inverter location. Locating arrays on the roof side nearest the electrical service and inverter minimizes wiring losses and balance-of-system costs.

For homes with a single service panel, placing panels on the side of the roof closest to the panel often reduces installation time and materials. If a battery backup is planned, placement that simplifies battery interconnection is advantageous.

When North-Facing Or Suboptimal Sides Are Used

North-facing roofs are usually the least productive in the U.S., but they still can be considered under specific circumstances. For shaded or historic sites where south exposure is unavailable, east/west layouts or elevated tilt systems can salvage production.

Dual-orientation systems (east+west) flatten daily output and may match load profiles better than a pure south system, possibly improving economics where time-of-use rates reward evening production.

Alternative Mounting Options

If the roof sides are unsuitable, alternative placements include ground mounts, carports, and trackers. Ground-mounted arrays allow ideal orientation and tilt but require land and permitting; trackers boost yield by following the sun.

Solar carports provide shade and dual use for parking areas, often delivering excellent orientation options. For limited space, building-integrated PV (BIPV) or thin-film modules on vertical facades can supplement generation.

Cost, Incentives, And Energy Yield Tradeoffs

Choosing the optimal roof side balances marginal energy gains against added costs. South-facing arrays typically maximize kWh per installed watt, but a west-facing array may provide higher value under peak pricing despite slightly lower annual output.

Federal tax credits, state incentives, and net metering policies affect payback. Homeowners should compare modeled energy yields, utility rates, and incentive structures to determine whether an east/west configuration or partial south tilt is more economical.

Installation Best Practices

Professional site assessment includes shade analysis, energy modeling, structural review, and permitting. Always request a detailed proposal showing estimated annual production by array section and by orientation.

Ask installers about module-level power electronics, roof-integrity warranties, and attachment methods. Confirm that the installer will coordinate necessary permits and HOA approvals when roof side changes aesthetics.

How To Decide: Steps For Homeowners

Homeowners can follow a systematic process: 1) Conduct a basic site review for shading and roof faces, 2) Request professional shading and energy modeling, 3) Compare proposals including yield, cost, and warranties, 4) Evaluate incentives and rate structures. Data-driven comparisons reveal which roof side offers the best return.

1. Inspect Roof Orientation And Shading Patterns At Different Times Of Day.
2. Obtain Detailed Energy Production Estimates For Each Candidate Roof Side.
3. Factor In Installation Cost Differences Due To Wiring, Racking, And Structural Work.
4. Consider Time-Of-Use Rates And The Value Of Afternoon Versus Morning Generation.

Real-World Examples And Typical Outcomes

In many U.S. homes, a south-facing array yields the highest annual output and simplest design. However, homeowners on time-of-use billing often see stronger economic returns from west-facing arrays that capture late-day peaks.

Urban homes with limited roof area often combine east and west arrays to smooth generation and align with morning and evening loads. Rural properties with open land frequently choose ground mounts oriented for ideal tilt and azimuth for maximum yield.

Frequently Asked Questions

Is South Always Best?

South is generally best for annual kWh, but not always for financial return depending on local rates. West-facing arrays can outperform south in markets with high late-afternoon electricity prices.

Can Solar Panels Be Installed On A Shaded Roof Side?

Partial shading reduces output and may require microinverters or optimizers. If shading is significant, relocation or alternative mounting is recommended for meaningful production.

How Much Less Efficient Is A North-Facing Array?

North-facing systems in the Northern Hemisphere can produce substantially less—often less than 60–70% of an equivalent south-facing system depending on tilt and latitude. They are usually a last resort unless architectural constraints apply.

Resources For Further Research

For accurate site-specific guidance, consult the National Renewable Energy Laboratory (NREL) PVWatts tool, local solar installers, and state energy offices. These resources provide production estimates, incentives, and technical guidance tailored to the homeowner’s location.

Homeowners may also request a solar site survey with shade measurements and a production model to compare roof-side options side-by-side before committing to installation.

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