PV substructure: rammed posts, screw piles, or ballast?

Three technologies, one question

Every ground-mount PV plant rests on tables, and every table needs an anchor. Soil geology, schedule, and CAPEX drive the choice between three approaches.

1. Rammed posts

C- or I-profiles driven into the ground 1.5–2.5 m deep by a hydraulic pile driver. The fastest method — 600–1,200 posts per shift in good conditions.

• Pros: lowest cost per MWp, very fast, no concrete.
• Cons: needs cohesive soil free of large stones; bends or fractures in rocky ground.

2. Screw piles

A threaded steel pile spun into the ground by a rotary head.

• Pros: works in rocky or loose soil; reversible — the land stays intact; ideal for slopes and agri-PV.
• Cons: ~30–50 % more expensive than ramming; slower install rate.

3. Concrete ballast

Concrete blocks or precast elements anchoring tables by mass alone, without penetrating the soil.

• Pros: ideal for landfills, brownfields, or sites where the substrate must not be pierced.
• Cons: the most expensive option; heavy logistics; higher static demands on the table.

Decision matrix

Our approach

Before every bid we recommend a pull-out test at 3–5 representative spots on the site. A few thousand euros for testing saves tens of thousands in change orders during execution.