Adding BESS to an Existing Solar Plant: A Cable Procurement Site Survey Checklist

Adding battery storage to an operating solar plant means working around infrastructure already in place. Existing cable routes, crowded cabinets and limited shutdown periods can all affect what buyers should order.

On 3 November 2026, ACCIONA Energía announced three BESS projects totalling 21.2 MW / 41.7 MWh alongside its Pedro Corto, Calabaza and Cotoperí photovoltaic plants in the Dominican Republic. The company stated that the projects would use existing infrastructure and reduce additional land requirements.

For a solar BESS retrofit, that opportunity comes with a practical procurement question: will the proposed cables and assemblies fit the actual site?

Complete the following survey before releasing the final cable order.

1. Walk the Existing Cable Routes

Start with available as-built drawings, then check them against the site. Record discrepancies rather than assuming the drawings reflect every modification.

Follow the proposed route from the new BESS equipment to the approved connection points. Include power, communication, earthing and auxiliary circuits.

Available space alone does not establish whether a route can accept more cables. Have engineering confirm support loading, cable grouping, thermal conditions and any required separation.

Survey output: A marked-up route drawing with photographs, dimensions and unresolved restrictions.

2. Verify New and Existing Equipment Interfaces

Record equipment nameplates, model numbers and terminal details at each proposed connection point. Where internal access is needed, arrange it through the site’s approved isolation and access process.

Collect:

• Current equipment drawings and terminal schedules.
• Terminal or connector manufacturer and part number.
• Permitted cable sizes and conductor types.
• Stud dimensions, lug orientation and termination clearances.
• Communication pinouts, shielding and earthing requirements.
• Responsibility for supplying mating components.

Older equipment may have been modified since installation. Verify the actual configuration before approving a replacement terminal or prefabricated assembly.

Confirm the selected retrofit architecture as well. An AC-coupled addition and a DC-coupled modification create different cable requirements.

Survey output: An interface register linking each cable end to a verified equipment connection.

3. Record Conditions Along Each Route

A single site-wide description such as “outdoor installation” is insufficient for battery cable procurement.

Divide the route into sections and record the conditions relevant to each one:

• Direct sunlight and ambient temperature.
• Enclosed, shaded or poorly ventilated spaces.
• Cable grouping and proximity to heat sources.
• Standing water, flooding or persistent moisture.
• Coastal salt exposure, dust or relevant chemicals.
• Abrasion risks, sharp edges and mechanical protection.
• Burial or duct conditions, including soil information where required for design.

These observations help the project engineer select the cable construction and assess current-carrying capacity, voltage drop and other design requirements.

Treat reuse of existing cables as a separate engineering decision. Appearance alone cannot establish their condition, rating or suitability for the new operating duty.

Survey output: A route-specific installation and environmental schedule.

4. Confirm Shutdown Windows and Installation Sequence

Cable design and delivery should reflect how the work can actually be completed.

Agree with the owner and installation team on:

• Which circuits require isolation.
• The duration and timing of available shutdown windows.
• Work that can be completed before the shutdown.
• Access restrictions and coordination with other contractors.
• The sequence for pulling, terminating, inspecting and commissioning.
• Responsibilities for site testing and handover.

For example, a factory-terminated assembly may reduce site termination work, but its connector may not pass through an existing duct. Confirm pulling clearances before choosing between prefabrication and field termination.

Match delivery batches to the installation sequence, especially where storage and laydown space are limited.

Survey output: An installation sequence linked to the delivery schedule and agreed outage plan.

5. Measure Finished Lengths and Define Labels

Measure the approved physical route, including vertical rises, cabinet entry paths, bends and termination positions. A straight-line distance between equipment locations is not a finished cable length.

For each energy storage cable assembly, define:

• Length measurement reference points.
• Routing and service allowances.
• Manufacturing tolerances.
• Branch positions and connector orientation.
• End labels and equipment identifiers.
• Packaging and installation grouping.

Where equipment positions remain provisional, mark the dimensions accordingly. Resolve them before releasing fixed-length assemblies for production.

Survey output: An approved cable schedule showing lengths, quantities, terminations, labels and drawing revisions.

Release Procurement Against a Complete Survey Package

A useful BESS site survey turns site observations into information the supplier can use.

Before final production approval, assemble the verified route drawings, interface register, environmental schedule, measured cable list and installation plan. Identify open items and assign an owner to close each one.

When requesting storage cables, battery connection harnesses, PCS harnesses or auxiliary assemblies from Winpower, share this package together with the electrical specifications and required inspection documents. Confirm which assemblies can be prefabricated and which dimensions or terminations still require site verification.

Accurate site information helps buyers order cables that fit the route, reach the terminals and arrive in the right installation sequence.