The project is one of the first high rise building buildings in central London to incorporate a large solar PV system, reducing carbon emissions and lowering the building’s electricity costs.

The solar installation at 5 Merchant Square was a technically challenging retrofit, delivering a 109kWp on-roof system across two roof spaces on the east and west cores of the building.

The system comprises 186  585W full-frame solar panels mounted on K2 mini rail, powered by four 25kW Eqonic string inverters. Each panel is fitted with a TIGO optimiser to boost performance, improve system safety, and allow for fast fault detection — essential given the sites limited access for future maintenance.

With no option to use lifting equipment on site, all scaffolding and solar equipment had to be moved through the building’s internal goods lifts to reach the roof as Mainland worked with specialist PHD Access.

This required careful planning, including four weekend visits to transport materials outside of weekday hours and minimise disruption to the building and its staff.

Despite the logistical challenges, the full system was installed and commissioned in just over eight weeks, and with 100% of the energy generated now being consumed on-site the client is predicated to save over £25,000 per year.

Mainland Power CEO Ryan Dignam said: “This installation marks a significant turning point for solar systems on London buildings, to retrofit may be difficult however it can be done and will reduce your carbon footprint whilst saving money for your business.”