Flachdach Aufständerung für Balkonkraftwerk Anleitung

Installing a flat‑roof mounting system for a balcony power plant (Balkonkraftwerk) on a flat roof requires a precise combination of structural analysis, component selection, and adherence to local building codes. This guide walks you through every decision, from wind‑load calculations to final torque settings, so you can achieve a safe, durable, and performance‑optimized installation.

Before you start, answer the core question: What tilt angle and ballast configuration will keep the array stable under the worst‑case wind conditions on your roof? The answer determines the size of the mounting frame, the number of support feet, and the concrete or paving‑slab weight you must add.

1. Structural Basics

Flat‑roof installations are typically “ballasted” or “penetrating.” Because most residential flat roofs are not designed to support heavy penetrations, a ballasted system is preferred. The key parameters are:

• Roof load capacity (kN/m²) – usually 1.5 kN/m² for lightweight roofs, 3.0 kN/m² for reinforced concrete.
• Wind zone – defined by local standards (e.g., Eurocode EN 1991‑1‑4). In Central Europe, zones range from 1 kN/m² (low) to 3.5 kN/m² (high).
• Panel array size – typical 2 × 400 W panels (≈ 2 m × 1 m each) weigh ≈ 24 kg per panel.
• Maximum tilt – 10° to 15° for flat‑roof ballasted systems to reduce wind‑drag.

2. Wind‑Load Calculation (Simplified)

Use the formula:

F = q·Cp·As
Where:
q = dynamic wind pressure (N/m²) = 0.5 × ρ × v² (ρ ≈ 1.25 kg/m³, v = design wind speed in m/s).
Cp = pressure coefficient (≈ 1.2 for a low‑rise flat roof).
As = projected area of panel array (m²).

For a typical 2‑panel array (2 m × 1 m, 10° tilt) and a design wind speed of 28 m/s (≈ 100 km/h, corresponding to zone 2), the resulting force is ≈ 750 N. This translates to a required ballast of about 75 kg per support foot when using a 0.6 m × 0.6 m base plate.

3. Component Specifications

4. Step‑by‑Step Installation

1. Site survey & roof assessment
   • Measure roof dimensions and check load capacity.
   • Identify any existing roof penetrations, drains, or HVAC equipment that might interfere.
   • Record wind zone and design wind speed from local building authority.
2. Design the layout
   • Calculate number of support feet (usually 4 for a 2‑panel array).
   • Determine tilt angle; aim for 10°–12° to maximize energy while limiting wind load.
   • Place rails parallel to the roof’s drainage direction to avoid water pooling.
3. Prepare the base plates
   • Clean roof surface; remove debris, oil, or loose material.
   • Apply a bituminous waterproof membrane or a proprietary roof‑protect pad under each plate.
4. Install support feet
   • Position the foot on the membrane, insert concrete anchors (if penetrating) or secure with ballast plates.
   • Check vertical plumb with a spirit level; adjust using shim plates if needed.
5. Attach mounting rails
   • Slide the rail into the foot’s channel and lock with M10 bolts.
   • Torque bolts to 20 Nm using a calibrated torque wrench.
   • Insert EPDM gaskets at the rail‑to‑panel interface to prevent moisture ingress.
6. Add ballast
   • Place concrete blocks on the foot’s base plate, ensuring the total weight meets the calculated requirement (e.g., 75 kg per foot).
   • Distribute weight evenly; avoid overhanging edges.
7. Mount the panels
   • Align panel frames with the rails, using clamp brackets at the upper and lower edges.
   • Secure clamps to 12 Nm (to avoid crushing the frame).
   • Connect panel wiring according to the manufacturer’s polarity guide.
8. Electrical connection & safety
   • Install a fused DC disconnect near the array, rated for the panel’s short‑circuit current (typically 10 A for 400 W panels).
   • Run conduit to the inverter location, using weather‑proof fittings.
   • Test ground continuity; resistance ≤ 0.1 Ω.
9. Final inspection
   • Verify all bolts are torqued and all ballast is seated.
   • Check wiring for correct polarity and secure terminations.
   • Perform a visual wind‑load test by gently pushing the array; it should not sway more than 5 mm.

5. Maintenance & Periodic Checks

Even though the system is ballasted, annual maintenance is essential:

• Ballast inspection – Ensure no block has shifted due to thermal expansion or roof settlement.
• Corrosion check – Examine steel components for rust; treat with zinc‑rich primer if needed.
• Electrical audit – Measure open‑circuit voltage and current; compare to datasheet values (±5 %).
• Roof condition – Re‑apply waterproofing membrane if cracks appear around the foot plates.

6. Common Pitfalls & How to Avoid Them

• Under‑estimating wind loads – Always use the highest wind speed for your region, not the average.
• Insufficient ballast – Use a safety factor of 1.2; i.e., add 20 % extra weight to the calculated requirement.
• Incorrect tilt angle – Going beyond 15° can dramatically increase drag, especially on low‑rise roofs.
• Ignoring roof membrane integrity – Place a protective pad under each foot to prevent punctures.

Tip: If you are uncertain about the roof’s load capacity, hire a structural engineer to perform a quick load test; the cost (≈ €150‑€300) is far less than a collapse or warranty claim.

For a ready‑made solution that meets the specifications listed above, check the balkonkraftwerk halterung flachdach series.