This 17kg high-density concrete ballast block is the standard weight used across UK ground-mount and flat-roof solar PV mounting systems, providing a cost-effective, non-penetrative method of holding racking systems securely in place without drilling into the roof membrane or ground.
Measuring 440 x 215 x 100mm, this is a standard Solid Dense 7.3N Concrete Block, Grey, 100mm — the block size specified by multiple UK solar mounting manufacturers, including GSE, Renusol, K2 and Van der Valk ballast trays and ground-mount frames, as their standard ballast unit.
7.3N
Compressive Strength
Please Note
Actual block weight varies between 17kg and 18.7kg depending on batch and manufacturer, as dense concrete block weight is not tightly toleranced. Always confirm the exact ballast weight per block with your mounting system's structural/wind-load calculation before ordering quantities.
Non-Penetrative Ballasting
Secures solar PV mounting frames and ballast trays to flat roofs or the ground without penetrating the roof membrane, preserving waterproofing warranties.
Industry-Standard Size
The 440 x 215 x 100mm format is the size specified by leading mounting system manufacturers as their reference ballast block.
High-Density Concrete
Manufactured from 7.3N dense concrete aggregate, giving the block the mass-to-volume ratio needed for effective wind uplift resistance.
Frost & Weather Resistant
Dense concrete construction is frost and moisture resistant, suitable for permanent outdoor exposure for the lifetime of the PV system.
Compatible With Major Mounting Brands
Matches the block size referenced in GSE, Renusol, K2 and Van der Valk ballast tray and ground-mount installation manuals.
Stackable & Easy to Handle
Manageable single-person weight and regular block shape allow blocks to be stacked and distributed quickly across ballast trays or racking feet.
Physical Specification
Weight
Approx. 17kg (batch variation 17–18.7kg)
Dimensions (L x W x H)
440 x 215 x 100mm
Material
Dense concrete aggregate block
Compressive Strength
7.3N/mm²
Finish
Standard textured face
Standards & Compliance
Manufacturing Standard
BS EN 771-3
Quality Assurance
ISO 9001
Environmental Certification
ISO 14001
Sourcing
BES 6001 Responsible Sourcing
Application
Primary Use
Solar PV ballast for flat-roof and ground-mount racking systems
Also Suitable For
General building construction, load-bearing internal/external walls above and below DPC
Installation
Loaded directly into ballast trays or stacked at racking feet per system design
Important Safety Information
Ballast quantity per module or per linear metre of racking must be calculated by a competent person using site-specific wind loading (BS EN 1991-1-4) and the mounting manufacturer's ballast tables. This block is a building material, not a certified ballast unit in itself.
How many of these blocks do I need per solar panel?
This depends on your roof height, location wind zone, panel tilt angle, and the specific mounting system's ballast table. Always follow your mounting system manufacturer's wind-load calculation or have a structural engineer confirm quantities — do not estimate.
Is this the same block used by GSE, Renusol, K2 and other mounting brands?
The 440 x 215 x 100mm dense concrete block format is the reference size quoted in the installation manuals of several major UK mounting system suppliers. Always check your specific system's manual, as some brands also accept alternative block or paving slab sizes.
Can these blocks be used on a pitched roof?
Some pitched-roof ballast systems (such as certain in-roof and rail-less kits) also specify this block size for ridge or hip ballasting. Refer to your mounting system's manual to confirm suitability for pitched applications.
Do the blocks need to be fixed down?
In most ballasted systems, the blocks are loaded loose into trays or cradles that are mechanically fixed to the racking — the block's mass itself is not fastened. Follow your mounting system's specific installation instructions.
Will the blocks damage my roof membrane?
When used correctly within a manufacturer-approved ballast tray or cradle, load is distributed across the tray footprint rather than concentrated at a point, minimising risk to the roof membrane. Always use the block within an approved ballast carrier, not placed directly on an unprotected membrane.
