Determining counterweight to prevent unanchored pv-system from being moved by the wind


The panels are on my flat roof in unanchored frames, and held in place with counterweights, to prevent the wind causing any damage. Companies installing panels may tend to increase the weight too much in their attempt to avoid any reliability issues. Yet in doing so the PV system may damage the roofing material or in my case, the underlying wooden support beams. So, how do you determine the right weight for the specific location?

There are a few variables:

  • local windspeeds (avg, min, max)
  • height of roof (the higher the roof the greater the wind velocity)
  • angle of the panels (the greater the angle the more wind it can catch)
  • weight of PV system itself (panels, frame)
  • surface area of PV system (m2).

I’d appreciate any input, including how you’d approach attempting to calculate it, any tools available, any variables I missed, etc.



Wow, if I understand you well, you’re essentially saying that your panels are just “sitting” on your roof right? If it’s correct… doesn’t that sound dodgy at all to you? Happy to be proven wrong but I’d say that sounds slightly against regulations to me. Better get your gear independently assessed to start with :thinking:

You might find some help here.