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SebastianLiesa22 Jul 2021 19:33Hello everyone,
As part of our house planning, we want to make all the preparations now to later install a photovoltaic system on our flat roof. We have already planned for an empty conduit to be laid from the flat roof to the utility room on the ground floor. Now, the construction company is asking what loads the roof should be designed for. We are currently contacting some suppliers.
Does anyone have experience or reference values regarding this? We definitely do not want the system to be rigidly attached to the roof or drilled in. It should be mounted on a frame, probably at an angle of about 25 to 30 degrees. Online, you often see figures of around 10 to 30 kg per square meter (2 to 6 pounds per square foot). Does that seem appropriate?
Thank you for your rough estimate.
As part of our house planning, we want to make all the preparations now to later install a photovoltaic system on our flat roof. We have already planned for an empty conduit to be laid from the flat roof to the utility room on the ground floor. Now, the construction company is asking what loads the roof should be designed for. We are currently contacting some suppliers.
Does anyone have experience or reference values regarding this? We definitely do not want the system to be rigidly attached to the roof or drilled in. It should be mounted on a frame, probably at an angle of about 25 to 30 degrees. Online, you often see figures of around 10 to 30 kg per square meter (2 to 6 pounds per square foot). Does that seem appropriate?
Thank you for your rough estimate.
No, probably not...
There are plastic supports with aluminum profiles onto which the modules are screwed. The plastic supports are filled with sand or similar material. To counteract wind loads on tilted modules, you’ll need more than the specified 30 kg/m² (6.1 lbs/ft²).
Alternatively, aluminum triangles can be screwed to the modules, with weights like paving slabs or similar used as ballast. Here, too, 30 kg isn’t enough.
And as always: Beware, this is just secondhand knowledge from an amateur, no guarantees whatsoever.
P.S. Consider combining a green roof with photovoltaics—I see that as an ideal combination...
There are plastic supports with aluminum profiles onto which the modules are screwed. The plastic supports are filled with sand or similar material. To counteract wind loads on tilted modules, you’ll need more than the specified 30 kg/m² (6.1 lbs/ft²).
Alternatively, aluminum triangles can be screwed to the modules, with weights like paving slabs or similar used as ballast. Here, too, 30 kg isn’t enough.
And as always: Beware, this is just secondhand knowledge from an amateur, no guarantees whatsoever.
P.S. Consider combining a green roof with photovoltaics—I see that as an ideal combination...
Yes, you’re right, if it is not supposed to be anchored, it requires more ballast! However, that shouldn’t be a major issue. Some systems reduce the necessary ballast by connecting entire rows. There are also special aerodynamic solutions.
They also wanted to enforce a green roof here, but that would have been economically unfeasible. You put greenery on it and then place a photovoltaic module over it, which is quite clever. Fortunately, they abandoned that idea.
They also wanted to enforce a green roof here, but that would have been economically unfeasible. You put greenery on it and then place a photovoltaic module over it, which is quite clever. Fortunately, they abandoned that idea.
Attention, this is just some gathered knowledge from an interested layperson and operator: The modules with a standard substructure alone weigh around 20 kg/m² (4.1 lbs/ft²).
Not drilling into the flat roof is definitely a good idea. However, as already mentioned, you will need to add ballast to the mounts. The amount of ballast required will certainly depend on your wind load zone. Find that out and then check the specifications of the components for the mounting system.
Not drilling into the flat roof is definitely a good idea. However, as already mentioned, you will need to add ballast to the mounts. The amount of ballast required will certainly depend on your wind load zone. Find that out and then check the specifications of the components for the mounting system.
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SebastianLiesa23 Jul 2021 13:11Do you have any recommendations for which manufacturer or supplier to contact for this? There are many posts online, but I need a precise calculation for the construction company.
Of course, I am familiar with the common suppliers, but I would still appreciate any suggestions.
Of course, I am familiar with the common suppliers, but I would still appreciate any suggestions.
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