What angle should solar panels be at?
Set the tilt roughly equal to your latitude for the best year-round output, which lands between about 30 and 45 degrees for most of the continental US. A home at 40 degrees north (Denver, Philadelphia, Columbus) does best near a 40-degree tilt; a home in south Florida or south Texas near 26 to 30 degrees wants a shallower 25 to 30 degrees. The idea is simple: you want the panel face pointed as squarely at the midday sun as possible, and the sun's average height across the year tracks your latitude.
In practice almost nobody builds a custom tilt on a pitched roof. Panels are mounted flush to the roof, so they take whatever pitch the roof already has, usually somewhere between 15 and 40 degrees. That is fine. Anywhere within about 10 to 15 degrees of the ideal tilt costs you only a few percent of annual production, so a standard roof is close enough that fighting for a perfect angle is rarely worth the money. The solar panel calculator lets you enter your roof's real tilt and see the effect on output.
Which direction should solar panels face?
In the Northern Hemisphere, including everywhere in the US, panels make the most energy facing true south, which is an azimuth of 180 degrees. True south is not the same as compass south: a magnetic compass points several degrees off from geographic south depending on where you are, so installers correct for that magnetic declination when they aim an array. Facing true south keeps the panels pointed at the sun through the strongest part of the day, from mid-morning to mid-afternoon.
Direction matters more than a flawless tilt, but there is a comfortable margin here too. Anything from southeast to southwest still captures roughly 90 percent or more of what a due-south array would make, so a roof that faces a little off south is not a problem. The choice gets more interesting when your only good roof planes face east and west, or when your electric rate changes by time of day, which the next two sections cover.
How much do you lose facing east or west instead of south?
A due east or due west array makes roughly 10 to 20 percent less energy over a year than the same panels facing due south, with the exact figure depending on your latitude and tilt. That is a real cut, but it is far from a dealbreaker: an east or west roof can still host a system that pays off, especially where electricity is expensive. If you have both east and west roof space, splitting panels across the two stretches production across more of the day instead of concentrating it at noon.
West often beats east once you factor in when the power is worth the most. A west-facing array peaks in the late afternoon, lining up with the evening demand spike and with the higher time-of-use rates many utilities now charge from roughly 4 to 9 pm. If you are on a time-of-use plan or sizing a system around a battery, that afternoon output can be worth more per kWh than a slightly larger total from an east or south roof. Run your usage through how much energy a solar panel produces to see how orientation shifts the daily curve.
Should you lay panels flat or adjust the angle by season?
A fixed tilt beats laying panels flat. A flat (0-degree) mount loses around 10 percent or more of the annual output you would get at your latitude tilt in most of the country, and worse, flat glass collects dirt, pollen, and standing water that a tilted panel sheds with rain. On a flat roof, installers use ballasted racks that tip the panels up to about 5 to 15 degrees, enough to self-clean and cut wind load without adding much height or cost.
Adjusting the tilt by season adds only a little. Steepening panels for winter and flattening them for summer can raise annual output by a few percent, typically under 5 to 8 percent, which is rarely worth the labor and the trips onto the roof for a fixed home array. Seasonal or manual adjustment makes more sense for a ground mount or an off-grid setup where you are chasing every winter watt-hour, since low winter sun is exactly when off-grid systems struggle, as do solar panels work in winter explains.
Do roof pitch and shade change the best angle?
On a rooftop, the pitch is a fixed constraint, so orientation and shade usually matter more than tilt. Most residential roofs sit between 15 and 40 degrees, which overlaps the ideal range for the continental US, so the roof you have is often close enough that the bigger questions are which direction the good planes face and whether anything shades them. A tree, chimney, or neighboring roofline that shadows even part of a string can cost more production than a slightly imperfect tilt ever would, which is why solar panel efficiency depends so much on clean, unshaded exposure.
When the roof will not cooperate, a ground mount lets you set the tilt and direction freely, aiming at true south and your latitude angle with no compromise, at the cost of yard space and more racking. That trade-off is the heart of ground mount vs roof mount solar. Either way, do not try to fix a shading problem with angle alone; hardware like microinverters or optimizers limits the damage when some shade is unavoidable.
How do you find the best angle for your location?
Start with two rules and then check them against a tool. Face the panels true south and set the tilt near your latitude, which you can look up for your city in seconds. That gets you within a few percent of ideal almost everywhere in the US, and for a rooftop system your existing pitch usually does the job on its own.
For an actual number, put your address into NREL's free PVWatts calculator, which models output for your exact location, tilt, and direction, or drop your details into the solar panel calculator to turn it into a panel count and a production estimate. Pair that with your local peak sun hours so you are sizing around the sun your address actually gets, not a national average.
Frequently asked questions
Is it better to tilt solar panels or lay them flat?
Tilt them. A tilted panel makes more energy because it points closer to the sun, and it stays cleaner because rain runs off instead of pooling. A flat (0-degree) mount typically loses around 10 percent or more of the output you would get at your latitude tilt, and it lets dirt and water sit on the glass. On a flat roof, installers tip panels up to about 5 to 15 degrees on ballasted racks so they self-clean and catch less wind.
Which is better for solar panels, facing east or west?
West usually wins in the US. East and west make roughly the same total energy over a year, but a west-facing array shifts its output to the late afternoon and early evening, which matches when household demand peaks and when time-of-use utility rates are highest. If you are on a time-of-use plan or pairing solar with a battery, that afternoon power is often worth more per kWh, so west edges out east.
Is morning or afternoon sun better for solar panels?
For raw energy they are similar, but afternoon sun is usually more valuable. Panels make comparable power from clear morning and afternoon light, so a due-east and due-west array produce close to the same yearly total. The difference is timing: afternoon and early-evening production lines up with peak household use and higher time-of-use rates, so afternoon sun tends to offset more expensive electricity. Morning sun helps most if your own usage is heaviest early in the day.
Do all solar panels need to face the same direction?
No. Panels on one string wired to a single string inverter should share a direction and tilt so one shaded or off-angle panel does not drag down the rest, but a system can absolutely span multiple roof faces. Microinverters or power optimizers let each panel work independently, which makes mixing east, south, and west planes on one system straightforward and is a common way to spread production across the day.
Does the exact angle really matter, or is close enough fine?
Close enough is genuinely fine for most homes. Being within about 10 to 15 degrees of the ideal tilt, and anywhere from southeast to southwest in direction, costs only a few percent of annual output. Since a typical roof pitch of 15 to 40 degrees already falls in the ideal range for the continental US, most rooftop systems do not need any tilt adjustment. Shade and direction move the number far more than a small tilt error, so spend your attention there first.