Solar Panel Orientation and Tilt Angle

Which way should solar panels face?

In the northern hemisphere, the short answer is true south. Panels that face south capture the most sunlight across the whole day and over the whole year, so a south-facing array is the benchmark every other orientation is measured against. If your roof faces south and sits at a sensible angle, you are already close to the best a fixed system can do.

But "best" is not the only goal. A growing number of homeowners deliberately point panels west to push production into the late afternoon and early evening, when household demand peaks and, under time-of-use (TOU) rates, electricity is most expensive. This guide covers direction, tilt, seasonal adjustment, how much you actually lose off-optimum, and the special cases of flat roofs and self-consumption.

How much you lose off true south

The penalty for facing the "wrong" way is smaller than most people expect. As a rule of thumb for a US rooftop:

• South = 100% (the reference).
• Southeast or southwest ≈ 95–98% — barely a difference.
• Due east or due west ≈ 80–85% — a 15–20% reduction, still very usable.
• North-facing ≈ 50–70% — poor, and generally avoided unless tilt is very low.

The takeaway: unless your only option is a steep north-facing slope, orientation rarely makes or breaks a project. East and west roofs are routinely worth covering, and many homes simply use both.

Optimal tilt: start with your latitude

For a fixed, south-facing array, the classic rule of thumb is to set the tilt angle roughly equal to your latitude. A home at 40° N (much of the central US) lands near a 40° tilt for the best year-round yield. In practice the curve is forgiving: anything within about 10–15° of optimum costs only a few percent, so most pitched roofs are already "good enough" without any custom mounting.

Two common refinements:

• Subtract a few degrees (latitude minus ~5–10°) to favor summer, when the sun is high and days are long.
• Add a few degrees (latitude plus ~10–15°) to favor winter, useful if your bills or usage peak in the cold months.

You can model any of these scenarios for your exact roof and zip code with our solar calculator.

Seasonal tilt: worth it?

Because the sun rides low in winter and high in summer, the theoretically ideal tilt changes through the year. Ground-mounted systems with adjustable racking can be tilted up steeply for winter and laid flatter for summer, squeezing out a few extra percent. For the vast majority of rooftop owners, though, the panels are fixed, and the gain from manual seasonal adjustment (typically only a few percent per year) rarely justifies the effort, cost, or roof access. Set a sensible fixed angle and leave it.

West-facing and self-consumption

If you are on a flat-rate plan and want maximum kilowatt-hours, south wins. But the economics change with self-consumption and TOU pricing. A west-facing array generates less total energy yet delivers more of it in the late afternoon and evening, when families come home, run appliances, and grid prices spike. Pairing that profile with what you actually use, rather than chasing peak total output, can mean a better bill even with lower production.

This is also why east-west split arrays are popular on flat roofs: they spread generation across morning and afternoon, flatten the midday peak, and often let you fit more panels (see row spacing below). For homes with a battery, the orientation question relaxes further, because stored midday surplus covers the evening regardless of which way the panels point.

Flat roofs: tilt frames and row spacing

A flat roof gives you a blank slate. Panels are mounted on tilt frames (ballasted or fixed) that set an angle, commonly a modest 10–15° rather than full latitude. A lower angle catches less direct winter sun but has three advantages: lower wind load, less ballast, and tighter row spacing, so you fit more panels in the same area.

That spacing matters because of inter-row shading: steeper, taller rows cast longer shadows and must be set farther apart, or the back row shades the front in winter. Lower tilt plus an east-west layout is the classic high-density flat-roof solution. The trade-off between angle, packing density, and yield is exactly the kind of thing your installer should model for your specific roof.

FAQ

Which direction is best for solar panels? In the northern hemisphere, true south for maximum annual energy. West is a strong choice if you want more afternoon and evening output under time-of-use rates.

What is the best tilt angle? A good starting point is a tilt roughly equal to your latitude. Within 10–15° of that, losses are only a few percent.

How much do east or west panels lose? Roughly 15–20% versus true south. North-facing is much worse (around 50–70%) and usually avoided.

Should I adjust tilt by season? Only practical for ground mounts with adjustable racking. For fixed rooftops the gain is small and rarely worth it.

Are east-west arrays a bad idea? No. They lower the peak but spread output across the day, fit more panels on flat roofs, and suit self-consumption well.

Bottom line

Face panels true south for the most energy, but do not panic if your roof points east or west; the loss is modest and often outweighed by fitting more panels or matching evening demand. Set tilt near your latitude, keep it fixed, and on flat roofs favor a low angle with proper row spacing. The right answer depends on your roof, your rates, and your usage, so model it before you commit. Start by checking how many panels you need and reading our installation guide.

Last updated June 2026. Informational only — optimal orientation and tilt depend on your location, roof, and utility rates; confirm with a qualified installer.