A ground mounted array is the answer when the roof is shaded, faces the wrong way, cannot carry the load or is not big enough for the demand. It buys you perfect orientation and easy access for cleaning and maintenance, and it costs more per kilowatt than a roof, because a roof is a structure you already own and a frame in a field is one you have to build.
What you pay for in a ground mount solar system
Foundations, frame, and a trench. Foundations are either concrete pads, driven piles or ground screws depending on ground conditions, and the ground investigation that decides which is a cost most people do not expect. The frame is steel or aluminium sized for wind. Then there is the cable run from the array to the building, which on a paddock or a yard can be a long trench through ground that has other services in it. Add security and fencing where the array is away from the building.
Ground based solar panels UK planning: a different question from a roof
Roof mounted domestic solar is frequently permitted development within limits. Standalone ground mounted generation has its own, tighter limits on size, height and siting, and they differ between England, Scotland, Wales and Northern Ireland and are narrower again in conservation areas, on listed curtilage and in national landscapes. On agricultural land the limits relate to the holding as well as to the array. Establish the planning position before design, because it is more often the constraint than the space is.
Where it clearly wins
Perfect tilt and azimuth rather than whatever the roof offers. No load on a structure that may not take it. Panels reachable from the ground, which makes cleaning, bird protection and fault finding a fraction of the cost over twenty five years. Room to expand later. On a farm, a workshop or a rural house with land and a poor roof, those advantages routinely outweigh the higher installed cost.
Where solar panels on ground level do not win
On a small domestic plot, where the array takes garden, casts shade, is visible to neighbours and needs planning. On sites with poor ground or high water tables, where foundations get expensive quickly. And anywhere the cable run to the building is long, because that trench is priced per metre and buys you nothing but distance.
A solar panel tracking system, and why almost nobody fits one in Britain
A tracker turns the panels to follow the sun through the day, and on paper it gains a useful amount over a fixed frame. In Britain it is rarely bought, for reasons that have nothing to do with the physics: it is a moving structure with motors, bearings and a controller, so it has a maintenance schedule and something to go wrong, it costs considerably more than the fixed frame plus the extra panels that would deliver the same output, and the gain is smallest exactly when the weather is diffuse, which is much of the year here. Fixed and slightly oversized is the normal answer. A tracker earns its place on a large ground mounted array where land is limited and somebody is already maintaining plant on site.
Questions people ask about ground mounted solar panels
Is a ground mounted array more expensive than a roof one?
Per kilowatt, usually yes, because of foundations, frame and the cable trench. It can still be the better investment where the roof is shaded, wrongly oriented or unable to carry the load, because a badly sited roof array underperforms for twenty five years.
Does a ground mounted array need planning permission?
More often than a roof array. Standalone installations have their own size, height and siting limits, and they are narrower in protected areas and on agricultural land. Check the position for your nation and site before spending on design.
What foundations does it need?
Concrete pads, driven piles or ground screws, chosen on ground conditions. That is why a ground investigation belongs in the early cost, not as a surprise after the quote.
Is a ground mounted array easier to maintain?
Considerably. Cleaning, bird protection, inspection and fault finding can all be done from the ground without scaffold or roof access, which is a real saving across the array's life.