Developing solar farms on unusable land requires a unique approach

The most common method for securing ground mount frames involves the use of heavy steel piles driven deep into the ground or concrete ballasts. Both are tried and tested and work to overcome reactions on the frames. The weight and size of these foundations is determined by the forces acting on the frame, but typically they need to be heavy and cumbersome. 

These ground mount frames often also need to be braced to protect against lateral forces. This is traditionally carried out with heavy rolled steel cross brace sections.

Bracing and anchoring frames using these traditional methods work well for most sites on flat, easily accessible land. However, when PV installations are being considered on traditionally unusable land such as remote locations, hilly or mountainous terrain, these heavy-duty methods of installation can be difficult or in some cases no longer viable. Just getting materials to site can be an expensive logistical challenge with traditional foundations and bracing adding tonnes of steel to haulage requirements. On top of this, these methods also require heavy plant machinery for installation, which again must be transported to and from site and can be limited by ground conditions.

In response to this, new lightweight easy-to-install products have been developed to brace and anchor solar ground mount frames and are already helping EPC companies and PV contractors to install on otherwise unusable land.

A range of steel wire rope ground anchors are now available which prevent uplift and can reduce the weight and size of piles and ballasts required or even replace them altogether. These ground anchors mobilize the density of the soil to overcome uplift and overturning. They can be delivered to site on pallets and easily carried and installed using just hand tools. These systems utilize existing technology, are tried and tested in demanding civil engineering applications for slope stability and erosion control, and provide like-for-like performance to traditional piles and ballasts as shown in these diagrams.

Similar lightweight steel wire rope kits are also now being applied for bracing frames and can provide comparable performance in protecting against lateral forces and moments when compared to traditional steel sections.

These steel wire rope PV bracing kits can be installed or even retrofitted to existing frames in as little as 20-30 seconds and can again be carried around the site by hand. Just like the ground anchors these bracing kits utilize tried and tested engineering and technology which is already used in seismic resistance and blast protection around the world.

From a transport and haulage perspective utilizing these lightweight products in place of heavy steel or concrete structures can have a significant impact from both a cost and logistical point of view, especially when installing on difficult or remote site locations.

For example, comparing a typical 3m brace made from 41mm strut (run from pile to pile), with a steel wire rope bracing kit made of 4mm diameter wire, the weight per brace is reduced by a significant 96% from 8.4kg to just 0.36kg. This can provide huge efficiencies in logistics, both in handling on site and with transporting materials where around 700 wire bracing kits can fit easily onto a transportable Euro Pallet.

Along with the logistical and materials handling benefits, these new steel wire rope solutions also offer significant embodied carbon savings compared to traditional heavy structures. For the bracing example mentioned, embodied carbon would be reduced by a staggering 95%. A clear environmental benefit that many developers will be keen to realize.

Wire rope solutions are also easier to retrofit, make decommissioning simpler, and can be installed using only hand tools with just basic training.

Reclaiming contaminated land such as landfill for solar energy generation has numerous benefits and can prove popular with landowners who can gain financially from otherwise unusable land.

However, installing solar racking and infrastructure on sites such as these is not straightforward. Ground invasive methods of installation which involve trenching or pile driving can often be difficult or even impossible due to legacy ground use, buried services, or instability. To prevent contaminated materials or groundwater leaking, many sites will feature a proactive cap which must be maintained.

This makes managing cables that are traditionally buried in trenches parallel to the arrays, particularly problematic as installers may be unable to excavate deep enough, if at all. Using heavy construction equipment can also be a problem as some sites may require minimal ground pressure to project the landfill cap.

Often the only solution is to move power and data cables above ground. To aid with this transition a new range of easy-to-install and manage systems are now available to help contractors route cables above ground, eliminating the need for heavy equipment and excavation work. 

Typically these solutions can be installed using just hand tools and feature a tensionable catenary line that runs along the racking or tracker and is fixed in place using brackets that mount directly to the existing frame structure.

Along with mitigating risks associated with excavation on these types of sites, moving cables above ground also comes with a range of other benefits. Above-ground cable management often proves significantly more cost-effective to install. Specialist labor and machinery costs are reduced, as the kits can be installed by hand with just power tools. Materials savings can also be realized, as by routing the cables above ground with free airflow, they do not need to be over-specified.

Moving into the O&M phase of a PV site, managing cables above ground also provides much greater control and predictability with less chance of damage from earth movement or burrowing wildlife. Where issues may arise, fault finding and maintenance are clearly much simpler thanks to visibility and access to the full cable system. Cable management is not the only challenge facing landfill or brownfield PV installations though. Racking and foundations can be equally problematic, with traditional heavy concrete ballasts often ruled out due to similar issues around the use of excavation equipment and the protective cap. Again utilizing lightweight but strong steel wire rope ground anchors to either completely replace or to complement smaller/lighter traditional foundations is a popular method of overcoming this issue.

More and more EPC companies and contractors are being asked to explore projects on unusable land. Whether this is reclaimed landfill sites or remote locations and challenging terrain, it will almost certainly require new ways of working.

Lightweight wire rope kits are easier to transport, handle on-site, are less ground invasive than traditional installations, and can support racking stability and foundations as well as cable management.

Such innovative and new solutions have the potential to be invaluable to those looking to develop in challenging, unused, or remote locations and make previously unworkable sites feasible to develop for commercial and environmental advantage. 

About the author

Dean Barlow is Gripple’s dedicated Solar Product Manager, based at the company’s head office in Sheffield, UK. Working with Gripple’s solar technical team Dean supports the global sales team and works closely with solar clients in the UK, USA and the rest of the world to provide manufactured solutions to on-site problems.