How Much Power Does Balcony Solar Produce? Output and Savings

"800 W" or "1,200 W" on a balcony solar kit is the most the system can deliver at any one moment, not what you'll get over a year. Annual output depends on where you live, which way the panel faces, and above all how steeply it's mounted.

Short answer: an 800 W balcony system hung vertically on a south-facing railing produces roughly 580 to 890 kWh a year across the US cities we modeled, and about 1,000 to 1,400 kWh tilted toward the south. A 1,200 W system makes about 1.5 times as much. It only saves money on the share you use as it's produced, because no state plug-in law pays for exported power.

How the systems work is covered in balcony solar explained. This page is the output and savings math.

How much electricity does an 800 W balcony system produce?

We ran NREL's PVWatts (version 8) for an 800 W (0.8 kW DC) system. Assumptions: open-rack mounting, PVWatts' default 14% system losses, a DC-to-AC ratio of 1.0, and no shading from the railing or neighboring buildings, which real balconies usually have.

In New York, the same system hung vertically facing west made 471 kWh/yr and facing east 498 kWh/yr, about 52% to 55% less than tilted south.

Why does the mounting angle matter so much?

A vertical panel on a railing faces the horizon, while the summer sun is high overhead at midday. Most balcony panels hang vertically because that's what a railing allows, and that alone costs about a third of the output. Vertical panels do comparatively better in winter, when the sun is low. Facing east or west roughly halves output compared with tilted south.

If the railing or a bracket allows a tilt, use it. Solar panel orientation and tilt explains the geometry, and how shading affects solar panels explains why a railing's shadow across part of a panel can cost more than its size suggests.

How do you estimate your own balcony solar output?

Use this rule of thumb:

Annual kWh ≈ rated kW × peak sun hours × 365 × 0.83 × orientation factor

• Rated kW: the system's watts ÷ 1,000 (0.8 for 800 W, 1.2 for 1,200 W), assuming the inverter is sized to match the panels.
• Peak sun hours: your area's daily solar resource. See peak sun hours explained.
• 0.83: PVWatts' default losses, 0.86 for 14% system losses × 0.96 inverter efficiency = 0.826. (Our solar output calculator defaults to a similar 0.8.)
• Orientation factor: 1.0 tilted toward the south; about 0.58 to 0.68 vertical facing south (the three PVWatts cities above; we use 0.63, their average); about 0.45 to 0.48 vertical facing east or west (the New York runs).

For tilted panels the formula lands within about 8% of the PVWatts runs: 800 W in Denver gives 0.8 × 5.0 × 365 × 0.83 = 1,212 kWh vs PVWatts' 1,313. Vertical estimates are rougher, because the real factor ranged from 0.58 to 0.68: Seattle comes out at 0.8 × 3.7 × 365 × 0.83 × 0.63 = 565 kWh vs 582, but Denver vertical at 763 vs 889. Expect up to about 15% either way.

Balcony solar output by region

Estimates from the formula, using the regional peak sun hours our solar calculators use, rounded to the nearest 10 kWh. The vertical columns use the 0.63 factor. Treat them as estimates before shading.

All figures in kWh per year, facing south. For east or west, multiply the tilted figure by about 0.45 to 0.48.

What does a 1,200 watt plug-in solar system produce on a typical day?

On a Midwest day of average sun: 1.2 × 4.5 × 0.83 = 4.5 kWh tilted, or about 2.8 kWh hung vertically (× 0.63). Instantaneous output comes close to 1,200 W only around midday in strong sun on a well-angled panel; mornings, evenings and cloudy days run far lower.

1,200 W is also the usual legal limit: as of October 2026, it's the cap in most enacted plug-in laws, with Colorado at 1,920 W and Maine at 420 W without an electrician. See is plug-in solar legal.

Why does only the power you use save money?

Every state plug-in solar law enacted as of October 2026 either excludes these systems from net metering or says nothing about paying for exports. Energy your home doesn't use at the moment it's produced flows to the grid for free. Connecticut's law requires devices to warn that, without a net meter, exported energy may be billed as usage. Laws change, so check your state's current text and your utility. Net metering explained covers how rooftop systems differ.

So the number that matters is your base load: the power your home draws all the time, from the refrigerator's cycling, the router, standby electronics and anything else that never fully turns off. In many homes it's a few hundred watts, but it varies widely. If a 1,200 W system is producing 1,000 W at noon and your home is drawing 300 W (illustrative figures), 700 W goes to the grid unpaid.

How to measure it: if your utility offers hourly smart-meter data, find the lowest hours overnight. An hour that used 0.25 kWh means an average draw of 0.25 × 1,000 = 250 W. Then check your daytime hours the same way, since that's when the panel produces.

To find which devices make up that always-on floor, a plug-through meter reads the watts and kWh of any 120 V corded device up to 15 A:

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To see your whole home's load second by second, including when midday demand sits below the panel's output, a panel-mounted monitor logs the mains and individual circuits; it installs inside the live panel, so that's work for a licensed electrician:

How much money does balcony solar save?

Annual savings = kWh you use yourself × your electricity rate

The table shows the ceiling, if every kWh were used at home, for an 800 W system hung vertically facing south. Rates are EIA's 2024 residential averages. Output is the PVWatts run where we have one, otherwise the regional estimate above.

Worked example: the New York City system makes 669 kWh a year. If your base load absorbs 70% of it (an illustrative share; yours depends on your load), you use 669 × 0.70 = 468 kWh, worth 468 × $0.2443 ≈ $114 a year. The other 201 kWh go to the grid for nothing.

Two cautions. EIA's average rate includes fixed charges spread over every kWh, and fixed monthly charges don't shrink when you use less, so check the per-kWh energy and delivery charges on your own bill. On a time-of-use plan, use the rate for the midday hours when the panel produces. The electricity cost calculator helps here.

Is balcony solar worth it?

Payback (years) = system cost ÷ annual savings

Plug in your own kit price. At the $114-a-year example, a kit costing P dollars pays back in P ÷ 114 years. The solar panel payback calculator runs the same math with your inputs.

It's most likely to be worth it when:

• Your rate is high, as in California, Connecticut or New York
• You have a south-facing, unshaded spot, ideally where the panel can tilt
• Your daytime base load absorbs most of the output, so little is exported
• You'll stay put long enough to reach payback, or can take the kit with you when you move

If midday exports are large, a balcony solar system with a battery stores some for the evening. For how full rooftop systems compare, see are solar panels worth it and how much electricity do solar panels produce.

Where to go next

• Balcony solar explained
• Is plug-in solar safe?
• Is plug-in solar legal?
• Solar panels for apartments and renters
• Run the numbers: solar output calculator and solar panel payback calculator

More in our solar and storage guides.