In this guide
Short answer: face the panels south (south-east to south-west is fine) and tilt them about 30 to 40 degrees. Compared with that ideal, a panel hung vertically on a south railing makes about 70%, a flat one about 88%, an east or west tilted one about 80%, and a north-facing one only about 30%. Shade costs more than any of these.
How much each placement makes
| Placement | Share of ideal output | 800 W kit, typical US site |
|---|---|---|
| South, tilted 30–40° | 100% | ~1,100 kWh/yr |
| South, flat on the floor or roof | ~88% | ~970 kWh/yr |
| East or west, tilted | ~80% | ~880 kWh/yr |
| South, vertical on a railing or wall | ~70% | ~770 kWh/yr |
| East or west, vertical | ~50% | ~550 kWh/yr |
| North, any | ~30% | ~330 kWh/yr |
Rounded factors, in line with typical NREL PVWatts results for mid-latitude US cities, assuming about 1,375 kWh per kW of panels a year at the ideal angle. They are the same factors our savings calculator uses; see the methodology. In the UK the pattern is similar, with lower totals.
Direction
In the northern hemisphere the sun is due south at solar noon. Every 15 degrees away from south costs a little at first and more as you approach east or west. A south-east balcony catches the morning and midday sun, which suits homes with breakfast loads. A south-west or west balcony produces later, closer to the evening peak; on time-of-use rates, those afternoon hours can be worth more per kWh.
Not sure which way your balcony faces? Open the compass on your phone, stand with your back to the building and read the heading. 180° is south.
Tilt
- 30 to 40 degrees is close to ideal across most of the US for year-round output. Southern states do slightly better with less tilt, northern states with more.
- Vertical (90 degrees) loses about 30% over a year but does relatively well in winter, when the sun is low, and snow slides off. It's also the easiest mount to get past a landlord.
- Flat (0 degrees) loses about 12% and gets dirty; the railing may shade it. A frame at 15 to 30 degrees is a cheap upgrade.
Shade is the biggest loss
Solar cells in a panel are wired in series, so shade on a few cells pulls down a whole section. A railing bar across the bottom row, a neighbor's balcony above or a tree for two hours at midday can cost 20 to 40% of the day's output. Bypass diodes in modern panels limit the damage, and panels with "half-cut" cells handle partial shade better.
- Watch your spot on a sunny day at 10 am, noon and 3 pm, and note the shadows.
- Raise the panel above the railing's shadow if your lease and building rules allow; otherwise hang it on the outside of the railing with rated hooks.
- Use two smaller panels on separate inverter inputs if part of your space is shaded, so the shaded one doesn't drag down the other.
- Keep them clean: a rinse in spring and after pollen season helps flat and low-tilt panels most.
What if my balcony faces north?
At about 30% of ideal output, a north-facing kit rarely pays for itself, even in high-price states. Look for another spot: a south-facing window sill (with a certified kit designed for it), a yard, a garage roof or a shared terrace. If there's no sunny spot, community solar may suit you better.
Ready to mount? See how to install balcony solar.
Frequently asked questions
Which direction should balcony solar panels face?
South is best in the US and UK. South-east or south-west lose only about 5%. East or west lose about 20% when tilted, more when vertical. North-facing panels make only about a third of a south-facing panel's output and are rarely worth it.
What is the best tilt angle for a balcony solar panel?
For the most output over a year, roughly 30 to 40 degrees from horizontal in most of the US. A panel hung vertically on a railing (90 degrees) makes about 30% less over the year but does relatively better in winter and sheds snow.
Are vertical balcony solar panels worth it?
Often, yes. A vertical south-facing panel produces about 70% of an ideally tilted one, needs no extra frame and is the easiest to get approved. On an east or west balcony, vertical panels drop to about half.
How much does shade reduce balcony solar output?
More than you'd expect. Shade on one corner of a panel can cut its output by a third or more, because the cells are wired in series. Avoid railings that shade the bottom row of cells, and put panels where they get direct sun from late morning to mid-afternoon.
Can I lay balcony solar panels flat on the floor?
You can, but a flat panel makes about 12% less than an ideally tilted one in the US, collects dirt and may be shaded by the railing. A low tilt frame of 15 to 30 degrees is usually better.
Update log
- Guide published. Factors match our calculator's methodology.
Sources and official texts