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Balcony Solar Calculator

Enter your balcony dimensions and orientation — get panel count, annual production, bill reduction estimate, and payback for apartment solar.

Your balcony dimensions and location
ft
ft
sq ft
$
Balcony solar system estimate
1 panel — 400 W system
Panels from railing1 panel (landscape)
Peak sun hours4.8 PSH × 100% orientation = 4.8 effective PSH
Annual production596 kWh/yr (49.6 kWh/mo)
Bill reduction (est.)9% of monthly bill
Annual savings$89/yr
System cost (est.)$560
Payback period6.3 yrs
Cost per watt (balcony)$1.40/W
Cost per watt (rooftop for comparison)$2.75/W installed
Balcony solar per-watt cost is higher than rooftop, but requires no roof access, no installer permit in most cases, and can move with you when you change apartments.
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Extended AnalysisLayout options, seasonal savings & regional regulations
W
hrs/day
$/kWh
Effective capacity: 560W after orientation and mounting correction. Annual production: 818 kWh.
Railing (vertical)70% of optimal
Vertical mount reduces production ~30% vs optimal tilt
Weight per panel: 11 kg — max recommended panels: 4
Wall-mounted (angled)82% of optimal
30-40° tilt bracket improves output vs vertical railing
Weight per panel: 14 kg — max recommended panels: 3
Floor-standing (tilted)100% of optimal
Optimal tilt bracket — best production but uses floor space
Weight per panel: 18 kg — max recommended panels: 2
Total system weight
22 kg
Check balcony load capacity
Orientation factor
100%
vs south-facing baseline

How to Use This Calculator

Measure your balcony dimensions

Measure the usable width along your railing — this determines how many panels fit side by side. Standard 400W solar panels are approximately 3.5 ft wide and 6.5 ft tall in portrait orientation. A 8 ft railing fits 2 panels; a 12 ft railing fits 3. Also measure your railing height — if it's less than 6.5 ft, panels may need to be mounted in landscape orientation (rotated 90°), which changes the count. If you have additional wall space, enter that square footage separately.

Set your orientation and region

Balcony direction is critical — south-facing captures full sun all day; east-facing only gets morning sun; west gets afternoon. North-facing balconies in the Northern Hemisphere produce very little (only diffuse light). Select your region for accurate peak sun hours. EU users: Germany, Austria, France, and several other European countries cap balcony solar installations at 800W — this calculator automatically applies the cap if your region requires it.

Choose your grid-tie method

Balcony power stations (plug-in microinverters, also called "solar generators for apartments") connect to your apartment's electrical system via a standard wall outlet. They require no electrician in most EU countries and most US states. Standard grid-tie inverters require an electrician but cost less per watt for larger systems.

The Formula

Railing Panels = floor(Balcony Width ÷ 3.5 ft per panel) Wall Panels = floor(Wall Area ÷ 22.75 sq ft per panel) Total Panels = min(Railing + Wall, 4, RegionCap ÷ 400W) System Watts = Total Panels × 400W Annual kWh = System Watts × PSH × 365 × 0.85 × Orientation Factor ÷ 1000 Bill Reduction % = (Annual kWh ÷ 12) ÷ (Monthly kWh usage) System Cost = Panels + Inverter + Mounting Hardware Payback = System Cost ÷ Annual Savings

The 0.85 system efficiency for balcony solar is slightly higher than typical rooftop systems because microinverters on individual panels avoid string shading losses. However, partial shading from railings, overhangs, and neighboring buildings can significantly reduce real-world output below these estimates.

Example

Anna — South-facing 8 ft balcony in Chicago

Anna lives in a Chicago apartment with a south-facing balcony 8 ft wide and a 4 ft railing. She pays $80/month for electricity and wants to know how much solar she can fit.

Balcony width8 ft
OrientationSouth (optimal)
Railing height4 ft (panels in landscape)
RegionUS — Central (4.8 PSH)

Result

Panels that fit2 × 400W = 800W system
Annual production~1,194 kWh/yr
Monthly production~99 kWh/mo
Bill reduction~18% of $80 bill
Annual savings~$172/yr
System cost~$1,000-1,200
Payback~6-7 years

For Anna, two 400W panels on her south-facing Chicago balcony offset about 18% of her electricity bill. While balcony solar won't cover her entire bill, it requires no roof access, no permit (in Illinois), and can move with her if she changes apartments. The ~7-year payback is acceptable given the system should last 25+ years.

EU 800W Balcony Solar Rules

The European Union has increasingly standardized rules for "balcony power plants" (Balkonkraftwerk in German). Key rules as of 2024-2025:

Germany

800W maximum inverter output for plug-in solar. Registration required with grid operator (simple online form) but no permit needed. Up to 2 panels (800W) connect via a standard Schuko outlet with a Wieland connector or standard plug. Germany changed from 600W to 800W in May 2024. No utility approval needed for systems within 800W limit.

Austria, France, Netherlands

Similar 800W caps with simplified registration procedures. France allows up to 3,000W for self-consumption with a Declaration of Conformity. Netherlands allows 800W plug-in. Always verify current rules with your national grid operator.

United States

No federal cap on plug-in solar. Some utilities require notification for grid-connected systems; some cities require permits for permanent installations. Check with your local utility and building department. Many apartment buildings prohibit exterior modifications — always get landlord or HOA permission before installation.

Australia

No national wattage cap but installations must comply with AS/NZS 4777 inverter standard. Many states allow plug-in systems up to 1,500W without permit. Check with your DNSP (Distribution Network Service Provider).

Apartment Solar Tips

Get permission first

Before buying panels, check your lease, building rules, HOA rules, and local permit requirements. Many landlords allow balcony solar if panels are within the balcony boundary and not visible from the street. Some building codes prohibit exterior attachments. Getting permission first avoids costly removal later.

Manage shading expectations

Upper floor balconies typically have better sun exposure than lower floors. Balcony railings, overhangs from the floor above, and neighboring buildings all reduce real output below calculator estimates. Use the orientation factor as a guide but expect 10-20% less production than open-sky calculations if there's any nearby shading.

Microinverter vs off-grid

Grid-tied balcony power stations (plug-in microinverters) are the standard for apartments — they put power directly into your apartment's circuit, reducing grid draw in real time. Off-grid setups (panel + battery + separate circuit) are more expensive, less efficient, and add complexity. Unless you specifically need battery backup, grid-tied is simpler and more cost-effective.

FAQ

In most places, yes — with caveats. You need: (1) landlord/building permission, (2) compliance with local electrical codes, (3) compliance with utility rules for grid connection. In Germany, Austria, and the Netherlands, the law explicitly allows balcony solar up to 800W with only a simple grid operator notification. In the US, no federal law restricts it but HOA rules and leases may. Always check before purchasing.
Typically 1-4 panels depending on balcony width and railing height. Standard 400W panels are 3.5 ft wide in portrait orientation. An 8 ft balcony fits 2 panels; a 12 ft balcony fits 3; a 16 ft balcony fits 4. Small 100-200W panels are available for very tight spaces. Most balcony power stations max at 2 panels (800W) to comply with EU limits and typical space constraints.
A balcony power station (also called "plug-in solar" or Balkonkraftwerk) is a complete system of 1-2 solar panels connected to a microinverter that plugs into a standard wall outlet. The inverter converts DC solar power to AC and feeds it into your apartment's electrical circuit, reducing grid draw. Popular brands include Deye, Hoymiles, and Enphase. Prices range $300-800 for a 400-800W system. No electrician required in most EU countries under the 800W rule.
Very little in the Northern Hemisphere — only diffuse sky radiation, not direct sunlight. Production is roughly 35% of a south-facing equivalent. At northern latitudes like Germany or the UK, a north-facing balcony may produce only 200-400 kWh/year from a 400W panel — barely covering the system cost before panels degrade. East or west facing balconies are significantly better than north.
Yes — this is one of the key advantages of balcony solar over rooftop solar. A plug-in balcony power station can be disassembled in an hour and reinstalled at a new apartment. The panels and microinverter are portable consumer electronics, not permanent fixtures. Most systems use quick-connect MC4 connectors for easy disassembly. This portability also means no depreciation hit on property value if you sell your apartment (since nothing is permanently attached).

Related Calculators

🪟 Wall-Mounted Solar Calculator
Calculate production from panels mounted vertically on exterior walls.
☀️ Solar Panel Calculator
Size a full rooftop solar system from your energy usage.
💰 Solar Savings Calculator
Estimate annual electricity bill savings from any solar system size.
🔋 Battery Bank Calculator
Calculate battery bank size for off-grid or backup power.

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