Will your ground take a solar foundation?
Drop in a UK postcode or coordinates. We pull live British Geological Survey data and tell you which foundation system fits your site.
Disclaimer: This report is an algorithmic estimate based on BGS data. Site-specific pull-out tests and utility surveys are mandatory prior to installation.
In short
Most ground-mounted solar in Britain stands on ground screws, steel piles wound into the soil in minutes with no concrete, no cure time and no water. Whether that works on your site is a question about what is under the topsoil: firm clay, sand and gravel take screws readily, made ground and shallow rock often do not, and peat rarely does. Type a postcode and this tool reads the British Geological Survey mapping for your area and gives a first read: screws, helical piles, or a site investigation before anyone quotes.
Worked example: A vineyard field on Oxford Clay
- –Ground: firm cohesive clay to depth, no superficial made ground recorded.
- –Recommendation: standard ground screws, typically 1.6 to 2.5 m embedment.
- –Confidence: regional mapping, so a pull-out test on the day of the first install confirms the design.
- –What it avoids: concrete foundations, which on the same field would mean excavation, curing time and a reinstatement cost at end of life.
What the ground usually means for the foundation
| Ground type | Usual foundation | What to watch |
|---|---|---|
| Firm clay | Ground screws | Straightforward; confirm with a pull-out test |
| Sand and gravel | Ground screws, longer embedment | Check the water table |
| Made ground or landfill | Ballasted frames | Do not penetrate a cap |
| Shallow rock | Rock anchors or drilled piles | Cost rises with drilling depth |
| Peat or soft alluvium | Specialist survey first | Screws may not develop capacity |
How this works
The check maps your postcode to the British Geological Survey superficial and bedrock deposits for that location, then applies our own installed experience of what each deposit means for screw capacity. It is a desk study, not a site investigation: it narrows the likely answer and flags where a pull-out test or a geotechnical survey is needed before a price is fixed.
Common questions
What foundations do ground-mounted solar panels need?
In most of Britain, ground screws: steel piles wound into the soil to between about 1.6 and 3 metres, carrying the mounting frame directly. Concrete is used where the ground will not take a screw, and ballasted frames are used where the ground must not be penetrated at all, such as a capped landfill.
Will ground screws work in clay?
Usually yes. Firm cohesive clay is good screwing ground and develops capacity quickly. Very soft clay and peat are the exceptions, where the screw may need to be longer, wider, or replaced by a different foundation altogether.
Do I need a geotechnical survey before installing solar?
Not always. A desk study against geological mapping is enough to design most sites, with a pull-out test on the day to prove the design. A full site investigation is worth its cost where the mapping shows made ground, peat, shallow rock or anything variable.
Can you put solar on made ground or an old landfill?
Yes, but not on piles. A capped landfill is covered with a ballasted system that sits on the surface, because driving anything through the cap risks the containment. That constrains the layout and adds weight, but it does not rule the site out.
Are ground screws reversible?
Yes, which is much of the point. A screw winds back out at end of life and the ground is left as it was, with no concrete to break up and remove. On tenanted or agricultural land that reversibility often matters more to the landowner than the install cost.