How Much Roof Space Do You Need for a Balkonkraftwerk mit Speicher?
Short answer: for a standard 2 kW Balkonkraftwerk mit Speicher you should plan on roughly 7–9 m² of unobstructed roof area. The exact figure moves up or down depending on the panel efficiency you choose, the tilt angle you set, and the clearance distances that local building codes demand.
System Size & What It Means for Roof Area
Balcony power plants with storage are usually sold in three common power tiers:
- 1 kW + 0.5 kWh battery
- 2 kW + 1 kWh battery
- 3 kW + 2 kWh battery
Each tier dictates how many photovoltaic (PV) modules you’ll need, and each module occupies a known physical footprint. The table below ties those tiers to the minimum roof space you’ll have to reserve.
| System Size (kW) | Typical Panel Wattage (W) | Panels Required | Panel Area per Module (m²) | Total Panel Area (m²) | Roof Footprint (incl. 20 % spacing) (m²) |
|---|---|---|---|---|---|
| 1 kW | 400 | 3 | 1.70 × 1.00 = 1.70 | 5.1 | 6.2 |
| 2 kW | 400 | 5 | 1.70 × 1.00 = 1.70 | 8.5 | 10.2 |
| 3 kW | 400 | 8 | 1.70 × 1.00 = 1.70 | 13.6 | 16.3 |
These numbers assume a ± 20 % margin for mounting rails, spacing between rows, and walkway clearance. If you use higher‑efficiency panels (e.g., 420 W or 450 W) the panel count drops, but the physical dimensions stay roughly the same, so the roof footprint doesn’t shrink dramatically.
Typical Panel Dimensions and Their Footprint
Most modern 400 W panels measure 1.70 m × 1.00 m (or 1.65 m × 1.00 m, depending on the manufacturer). Their active area is about 1.55 m², but when you add the frames, mounting brackets, and a safety gap of 5 cm on each side, the effective “roof footprint” per panel rises to roughly 1.7 m².
Weight is another factor you can’t ignore. A single 400 W panel weighs about 20 kg (including the glass, backsheet and frame). When you add the mounting rail system (≈ 2 kg per panel) and any ballast blocks required on flat roofs, the total load on the roof structure reaches ≈ 22 kg per panel. For a 2 kW system (5 panels) that’s a distributed load of ≈ 110 kg – well within the capacity of most pitched roofs, but you must check flat‑roof load limits.
Step‑by‑Step Roof‑Area Calculation
Follow this checklist to translate the numbers above into a concrete roof‑space plan for your balcony system:
- Measure usable roof dimensions – record the length and width of the section you can actually use, subtracting any obstacles (vents, skylights, HVAC units, neighboring panels).
- Determine orientation and tilt – a south‑facing roof at a 30° tilt yields the highest specific yield (≈ 140 kWh/kWp per year in central Germany). If the roof faces east or west, you lose roughly 10‑15 % of the
