In an apartment, you are limited by available space, legal constraints, and the permitted power for plug-and-play devices ( 800W maximum without an electrician ). The question is not "how many do you want to install" but "how many can you install given your layout".

Quick answer: number of panels depending on your situation

Balcony 3-4 m²: 1 x 400W panel → 360-560 kWh/year → Savings €60-95/year

Terrace 6-8 m²: 2 x 800W panels → 720-1120 kWh/year → Savings €120-190/year

Guardrail only: 1-2 vertical panels depending on the length (1 panel/2 meters)

Without outdoor space: collective project on a condominium rooftop (8-20 panels depending on surface area)

Maximum allowed without complex declaration: 800W = 2 panels of 400W. Beyond that, it is mandatory to use a RGE-certified electrician.

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Calculation based on your electricity consumption

Sizing based on annual consumption

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How to identify your consumption

Via Linky meter:

• Enedis app (free): monthly consumption history

• Supplier application (EDF, Engie, etc.): real-time tracking

• Latest bill: total kWh consumed over 12 months

Averages according to housing type:

• Studio/T1 (25-35m²): 2500 kWh/year

• T2 (45-60m²): 3500 kWh/year

• T3 (65-80m²): 5000 kWh/year

• T4+ (80-100m²): 6500-8000 kWh/year

Important: these panels only cover part of your needs. The goal in an apartment is to reduce your energy bill, not to achieve total energy independence (impossible with the available space).

To choose the right kit for your consumption, analyze your daily consumption peaks.

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Calculation based on available space

Surface area required per panel

Standard dimensions of a 400W panel:

• Width: 100-110 cm

• Height: 170-180 cm

• Panel surface area: 1.7-2 m²

• Total floor area required with a 30° incline: 2.2-2.6 m²

Mandatory spacing:

• Between 2 panels: minimum 15 cm

• Around the panel (maintenance): 20 cm

• For optimal incline: +30% floor area

Check the exact dimensions for each model before purchasing.

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Configuration according to the type of space

Practical rule:

• 1 standard panel = 2 m² minimum floor area (with incline)

• Guardrail = 1 panel every 2 linear meters

• Limit 800W in plug and play = maximum 2 panels of 400W

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Orientation and yield losses

Is your balcony not facing due south? Here are the actual heat losses:

• South: 100% yield (reference)

• Southeast or Southwest: -5% to -10%

• East or West: -20% to -25%

• Northeast or Northwest: -40% to -50%

• North: -60% to -70% (unprofitable installation)

An east- or west-facing panel remains cost-effective if your energy consumption is concentrated in the morning or evening. Analyze the advantages and disadvantages based on your preferred orientation.

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Legal and technical constraints

Installation rules according to your status

Condominium owner:

• Check the condominium regulations (some prohibit facade modifications)

• Balcony installation <1.80m from the ground: no authorization

• Balcony installation >1.80m: prior declaration to the town hall (response within 1 month)

• Micro-inverter limit 800W without Enedis declaration

Tenant :

• Written agreement from the owner required

• Opt for removable panels (which can be transported during a move)

• Temporary fixing of the condominium wall without drilling

• Same limit 800W

Condominium roof (collective project):

• Vote in the general assembly by absolute majority

• Declaration of works at the town hall

• Network connection: collective contract

• Distribution of production among co-owners

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Maximum 800W: why this limit

French regulations allow up to 800W in plug and play mode without an electrician or complicated procedures:

• Simple plug-in to a standard household outlet

• No modifications to the electrical installation

• Simplified Enedis declaration (online form)

• Compatible with existing meter

Above 800W, you switch to a conventional installation:

• RGE certified electrician required

• Electrical panel modification

• Specific connection

• Installation cost multiplied by 3-4

In an apartment, 2 panels of 400W = optimal maximum configuration .

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Actual production depending on the configuration

1 x 400W panel

Annual production: 360-560 kWh depending on the region

• Northern France: 360-420 kWh/year

• Center France: 420-500 kWh/year

• Southern France: 500-560 kWh/year

What this covers continuously (based on 400 kWh/year):

• Internet box (150 kWh/year) ✓

• Class A refrigerator (130 kWh/year) ✓

• LED lighting in the home (100 kWh/year) ✓

• Total: 380 kWh/year, fully covered

Annual savings: €60-95 (rate €0.17/kWh)

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2 x 800W panels

Annual production: 720-1120 kWh depending on the region

What this covers in addition to the base amount (800 kWh/year):

• Base above (380 kWh)

• Washing machine: 10 cycles/month (150 kWh/year)

• Dishwasher: 15 cycles/month (200 kWh/year)

• Laptop used 6 hours/day (50 kWh/year)

• Total: 780 kWh/year covered

Annual savings: €120-190

Discover the best 800W kits for this configuration.

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With storage battery

Without a battery, you only consume 40% of your production (the rest is injected into the grid for free during the day).

With battery:

• Self-consumption rate: 40% → 85%

• Production 800 kWh/year

• Actual self-consumption: 680 kWh instead of 320 kWh

• Additional savings: 360 kWh = €60/year

• Battery investment: €900-1500 for 1.5-2 kWh

• Profitability: 15-25 years (with a 15% annual decrease in battery prices)

Complete guide: Which battery for plug and play solar panels

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Solutions depending on the type of apartment

Studio/One-bedroom apartment (25-35m²)

Consumption: 2000-3000 kWh/year
Solution: 1 x 400W panel
Production covered: 15-25%
Investment: €400-600
Profitability: 6-8 years

Typical configuration:

• 1 x 400W panel on balcony or railing

• Integrated micro-inverter

• Plugs into a standard outlet

• Without a battery (not cost-effective)

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T2/T3 (50-70m²)

Consumption: 3500-5000 kWh/year
Solution: 2 x 800W panels
Production covered: 20-30%
Investment: €800-1200
Profitability: 5-7 years

Typical configuration:

• 2 x 400W panels on a continuous terrace or balcony

• 800W Micro-Inverter

• Series wiring between panels

• Optional 1.5 kWh battery (+€900)

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T4/T5 (80-100m²)

Consumption: 6000-8000 kWh/year
Solution: 2 x 800W panels + 2 kWh battery
Production covered: 15-20% (but optimized)
Investment: €1800-2500
Profitability: 8-10 years

Typical configuration:

• 2 x 400W panels, optimal tilt

• 2 kWh storage battery

• Intelligent charge/discharge management

• Consumption tracking app

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No balcony/terrace

Solution: collective project on the roof of a condominium

• 8-20 panels depending on roof area

• Production 6000-15000 kWh/year

• Allocation between co-owners (allocation key)

• Reduction in common charges (lighting, elevator)

Procedures:

• Form a group of interested co-owners (minimum 3-5)

• Feasibility study by RGE-certified installer

• Vote in the general assembly by absolute majority

• Possible subsidies (local authorities)

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Special cases and optimizations

Partially shaded balcony

If the panel receives shade for 3-4 hours/day:

• Production loss: 30-50%

• Solution: power optimizers (1 per panel)

• Cost: +€100-150 per panel

• Extended profitability: +2-3 years

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Temporary installation (tenant)

Prioritize:

• Strap/tensioner fixings (no drilling required)

• Portable, demountable panels

• Weighted supports (20-30 kg)

• Micro-inverter with removable plug

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Maximize production in limited space

Bifacial panels: capture light from both sides

• Production: +10-20% vs standard

• Price: +15-20%

• ROI: same but higher production

Solar trackers (follow the sun):

• Not suitable for balconies (bulky)

• Alternative: manual summer/winter tilt adjustment

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Conclusion

Number of panels depending on your apartment:

• Studio: 1 panel (400W)

• T2/T3: 2 panels (800W)

• T4+: 2 panels + battery

• No balcony: collective rooftop project

Regulatory limit: 800W maximum, plug and play, without an electrician

Profitability: 5-8 years depending on configuration, then 15-20 years of free production

Minimum space: 2 m² per panel (4 m² for 2 panels)

Most apartments can accommodate 1 to 2 panels. Beyond that, space constraints and regulations make the project complex and unprofitable.