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Balcony Power Plant Flat Roof Weighting: How Much Ballast Is Necessary?

Balcony Power Plant Flat Roof Weighting: How Much Ballast Is Necessary?

Installing a balcony power plant on your flat roof is a sustainable move to harness solar energy and save on energy bills. However, proper weighting of such an installation is paramount for stability, safety, and its structural integrity. So, how much ballast is necessary for balcony power plant flat roof weighting?

In this guide, we’ll help you calculate how much weight is necessary for your balcony power plant on flat roof and provide practical advice to secure your setup against the elements and architectural concerns.

Why Does the Balcony Power System on the Flat Roof Have to Be Weighed Down?

Installing a balcony power system on your flat roof isn’t simply a matter of setting up panels and reaping the benefits of solar power. The need for proper weighting or ballasting of these systems is critical and serves several crucial purposes:

To Withstand Wind Pressures

Flat roofs are particularly susceptible to wind pressures due to their expansive and unobstructed nature. Without sufficient weight, solar panels and their frames can act like sails, catching wind and potentially causing damage. Proper weighting ensures that the system remains stable and anchored, even during high winds that could otherwise lift or shift the panels, leading to potential hazards.

To Maintain System Stability

Solar panels mounted on flat surfaces require a stable base to maintain optimal alignment with the sun. Any shift in positioning could reduce the efficiency of energy collection. Weighting down your balcony power plant helps maintain this necessary stability, ensuring that the panels stay in the correct orientation regardless of external factors like weather or incidental contact.

To Avoid Roof Penetration

Traditional mounting systems often involve drilling into the roof to secure the solar panels, which can lead to waterproofing and structural issues. By using weights to anchor the system, you can avoid penetrating the roof’s surface, thus preserving the integrity and longevity of the roofing material. This method not only prevents potential leaks but also simplifies the installation and removal process, making it less invasive and more adaptable to various building codes and regulations.

How Much Weight for the Balcony Power System on the Flat Roof?

Determining the right amount of weight to secure a balcony power system on your flat roof involves several considerations, from local regulations and the load-bearing capacity of the building to environmental conditions. Let’s explore further:

Understand your Local Building Codes

In Germany, building codes can differ significantly across federal states. These regulations, particularly those related to DIN 1055-4 standard, often specify the minimum requirements for rooftop installations, including the weight and method of securing systems. It’s crucial to start by consulting your local building authority or codes to understand the specific requirements for your area. This ensures that your installation adheres to legal standards and safety guidelines.

Calculate Wind Load

Accurate wind load calculation is essential for determining the appropriate weight needed to secure your balcony power system. You can use specialized tools and mathematical formulas tailored to local wind conditions to enable precise assessments of the forces exerted on the installation.

Here’s a process based on the DIN 1055-4 standard for calculating wind loads on structures:

  1. Determine Basic Wind Velocity:Refer to DIN 1055-4 standard maps or consult the German Weather Service to find the basic wind velocity for your specific location based on wind zones.
  2. Adjust for Terrain Category:Choose the appropriate category from I (open terrain) to IV (urban areas) based on the surrounding environment to modify the basic wind velocity using the terrain factor.
  3. Calculate Site Wind Velocity (Vs): Multiply the basic wind velocity by the terrain factor to get the site wind velocity.
  4. Calculate Peak Velocity Pressure:Use 𝑞ρ = 0.5 × 𝜌 × 𝑉𝑠2, where ρ (air density) is typically about 1.25 kg/m³. This calculates the peak wind pressure based on site wind velocity.
  5. Determine Wind Load: Use coefficients specific to flat roofs from DIN 1055-4 to factor in how wind impacts the roof's geometry. Consider the area of the roof covered by the solar installation.
  6. Calculate Wind Load:𝐹𝑤=𝑞𝑝 × 𝑐𝑝𝑒 × 𝐴𝑒, combining peak velocity pressure, roof coefficient, and effective area.

Calculate Snow Load

Snow load is another crucial factor to consider when securing a balcony power system on a flat roof in Germany, especially in regions prone to heavy snowfall. Snow can add a significant amount of weight to the roof and, by extension, to your solar installation, which must be accounted for to prevent structural damage or collapse.

Germany adheres to the Eurocode standards (EN 1991-1-3), which provide guidelines for calculating snow loads on structures. These standards consider factors such as the altitude of the area, typical snowfall, and the shape and thermal characteristics of the roof. For flat roofs, the risk of snow accumulation is higher, and the load calculations must reflect this risk.

Consult a Structural Engineer or Other Professionals

Given the complexity of factors involved in securing a rooftop solar system, consulting with a structural engineer or a specialist in solar installation is highly advisable. These professionals can provide a detailed assessment of your specific situation, taking into account the structure of your building, roof condition, and the calculated wind or snow loads. Their expertise will guide the correct placement and amount of weight needed to ensure safety and functionality.

Other Tips for Balcony Power Plant Installation

Installing a balcony power plant on your flat roof requires careful planning and attention to detail. Here are several additional tips that can enhance the safety, efficiency, and longevity of your installation:

  • Choose the Right Solar Panels and Mounting Systems: Opt for high-quality, durable solar panels that can withstand local weather conditions. Consider factors like efficiency, warranty, and the manufacturer’s reputation. Additionally, select a mounting system that is specifically designed for flat roofs. These systems should minimize roof penetration and be adjustable to optimize the angle of the panels for maximum sun exposure.

For instance, the Anker SOLIX Balcony Solar Power System (2*RS40B Panel 410W, Micro Inverter 600W/800W, Balcony Brackets), features solar panels with top-tier 23% efficiency and a 12-year warranty. The included mounting brackets are engineered to ensure minimal roof penetration and allow for angle adjustments to maximize solar capture throughout the day.

  • Roof Reinforcement:Reinforce the flat roof structure if necessary to accommodate the additional weight of the balcony power system. This may involve adding extra support beams or reinforcing existing structural elements to ensure stability and safety.
  • Optimize Panel Placement:Place solar panels in areas where they will receive maximum sunlight throughout the day. Avoid locations that are prone to shading from nearby buildings, trees, or other structures.
  • Maintenance Access:Ensure that the balcony power system design allows for easy access to components for maintenance and inspection purposes. This facilitates regular upkeep and troubleshooting while minimizing the risk of damage to the roof or surrounding areas.


Balcony power plant flat roof weighting plays a crucial role in ensuring the stability and longevity of the installation. By understanding local building codes, calculating wind loads, and consulting with professionals, you can balance your system with the right amount of ballast. Not only does this protect your property, but it also guarantees the efficiency and longevity of your solar power setup. With the right preparations and expert advice, your balcony power plant can be a reliable and effective contributor to your home’s energy needs for years to come.


How much weight does a flat roof have to withstand?

In Germany, the weight a flat roof must withstand is primarily dictated by building codes and the DIN 1055-4 regulation. Generally, flat roofs are required to support a minimum load of 75 kilograms per square meter (kg/m²), which accounts for snow load and potential temporary loads. This can vary based on regional snow load zones and the specific construction and design requirements of the building.

Is a permit required to install a balcony power plant on a flat roof?

In Germany, installing a balcony power plant on a flat roof typically does not require a permit. However, tenants should seek approval from their landlord, and homeowners should check any applicable local regulations or building codes.

How can the weighting of a balcony power plant be securely and permanently attached to a flat roof?

To securely attach the weighting of a balcony power plant to a flat roof, it’s essential to use a ballast system that does not damage the roof’s integrity. Commonly, weights such as concrete pavers or specially designed ballast blocks are used. These weights should be evenly distributed across the base of the power plant to maintain stability and prevent any movement due to wind or weather conditions.