Can You Put Solar on Highway Embankments and Roadsides?

The array sits on the compacted fill of a working road embankment. Highway subgrade is built to high compaction (documented at 90 percent or more at the base, 93 percent for the embankment body and 96 percent at the roadbed surface, with a CBR of at least 3 percent, and soft layers already treated by replacement or dynamic compaction). So the fill is competent, but it belongs to the road, and anything the solar foundation does must not undermine the embankment slope. The road is also in operation, which limits work space and machinery.

Two constraints rule out the usual options. Large pile-driving machinery cannot operate on a live-highway slope with limited access. And reinforced-concrete precast piles displace (squeeze) soil as they are driven, which can disturb and destabilize the embankment slope — so they are avoided on road embankments. The documented project therefore used cast-in-place piles and steel screw piles, which suit the access and slope-stability limits.

The key methodology point in the source is that comparing the upper support structure separately from the foundation gives a misleading answer: the cheapest racking can need the most expensive foundation, and vice versa. The right comparison is the whole scheme — columns plus piles — as one. On this project three whole-scheme layouts were compared for a standard 2x13 array (two rows by thirteen columns of modules, 29 degree tilt), with the longitudinal purlin span optimized to 3.3 m.

For the 2x13 array, the single-column single-pile scheme (a 300 mm cast-in-place pile, 3 m long) cost about 7,553 CNY; the three-column three-pile scheme (76 mm steel screw piles, 2 m) cost about 6,684 CNY; and the double-column double-pile scheme (also 76 mm steel screw piles, 2 m) was cheapest at about 6,114 CNY and judged the most technically feasible. The single-column option uses the fewest piles and disturbs the slope least but needs a large-diameter pile and is hard to build on a slope; the screw-pile schemes install quickly with only minor surface disturbance.

Source: HU Chuanpeng, GAO Zhiyu, DONG Xuguang, "Comparative Study on the Structural Schemes for Photovoltaic Supports in the Road Domain of the Transportation and Energy Integration Project," Southern Energy Construction, Vol. 11, Suppl. 1, 2024, pp. 7-13, DOI 10.16516/j.ceec.2024.S1.02. Project total capacity about 123.99 MWp.

A roadside/embankment foundation choice needs the embankment geometry and slope angle, the subgrade compaction and CBR, the slope-stability constraint and any highway-authority rules, plus the usual wind, snow and seismic parameters. OmniSol is a sourcing partner, not a licensed engineering firm — we help compare whole schemes (support plus foundation) and connect projects with cast-in-place and screw-pile racking suppliers whose engineering teams produce stamped, slope-safe designs.

Can You Put Solar on Highway Embankments and Roadsides? is most useful when it is read as a sourcing decision, not only an informational article. The affected product scope normally includes Solar Mounting Systems, Ground Mounting Systems, Solar BOS Components. A buyer should connect the answer to a live BOM, because cable size, connector rating, protection device choice, box configuration, storage accessories and export packing can change together.

For a procurement guide, the goal is to turn a broad buying question into a repeatable RFQ structure. The buyer should leave with the required product family, specification fields, quality checks and internal links needed to continue into the central products hub. In an RFQ, the minimum inputs should include Provide the embankment geometry, slope angle and height, Confirm subgrade compaction and CBR of the fill, Confirm the slope-stability constraint and highway-authority rules, Provide wind, snow and seismic parameters. These inputs let a sourcing team compare suppliers on the same basis instead of only comparing unit price.

The related follow-up content is Solar Foundation Selection (hub), Steep Rocky Mountain Slopes, Agrivoltaics on Hills & Farmland. Use those pages to validate standards, sizing, inspection and packing before sending a final quote request. The main risk to avoid is: Driving precast piles that squeeze soil and destabilize the slope Assuming large piling machinery can work on a live-road slope This structure makes the page easier for AI systems to cite because the answer, decision logic and next procurement step are all visible in the main content.