Commercial solar for retail.

This page is for the operators behind retail parks, superstores, grocery and food formats, and the larger high-street and trade-counter units. The estate runs on electricity through every trading hour, and it tends to sit under wide, flat, lightly shaded roofs that were built to carry plant. That combination is what makes commercial solar worth modelling here rather than assuming.

The case is not the roof on its own. It is the load underneath the roof, and how much of the day that load lines up with generation. For most retail buildings the answer is encouraging, but it varies by format and by site, which is why the only honest way to size a retail array is from your actual half-hourly demand.

Retail self-consumes well for a simple reason: the building is open and drawing power through the brightest part of the day. Lighting runs across the whole floorplate, HVAC works hardest in the summer cooling season when generation is also at its peak, and on food and grocery formats the refrigeration and chilled cabinets pull a continuous baseload that never really stops. That demand profile is a close match for what a rooftop array produces, so a high share of the generation is consumed on site. Every unit used that way offsets an expensive import unit, while a unit exported is paid far less, so the daytime match is where the value sits.

The match is strongest on energy-intensive grocery and on formats that trade long hours, and it is softer on units that close early or carry a lighter electrical load. None of this is a rule of thumb on our side. We read it from your meter, because two stores under identical roofs can return very different self-consumption once you look at when the power is actually drawn.

Retail roofs tend to be the easy ones: large, flat or shallow-pitch decks over superstores and retail-park units, often with long unobstructed runs broken only by rooflights and rooftop plant. As an indicative orientation only, retail-park and superstore sites commonly fall in a 100–500 kWp band, with grocery and the larger anchor units sitting toward the upper end. Treat that as a sense of scale and nothing more. The real figure comes from the on-site survey and the PV*SOL model, which size the array to your roof and your demand rather than to a category average.

A retail roof is rarely empty underneath. The store keeps trading while we work above it, and that single fact shapes the whole programme. Roof access has to be planned so that loading, lifting and the safe drop zone never cross a live customer route or a service yard in use, and the noisiest work is sequenced around delivery slots and peak footfall rather than against them. On a retail park with several occupiers under one freeholder, the same care extends to the neighbouring units and the shared car park, so the works plan is agreed with the centre management before a single panel is craned up.

This is where the statutory framework does real work rather than sitting on a certificate. A commercial array over 50 kWp is a construction project under CDM 2015, so a Principal Designer and a Principal Contractor are appointed and a construction phase plan is written for the specific building. On an occupied trading store that plan is not a formality. It sets out the segregation between the works and the public, the roof-edge protection, the route for materials, and the method for working near live electrical plant and rooftop kit. The wiring is installed and tested to BS 7671, the completed system is commissioned and documented to IEC 62446-1, and the whole job runs under a JCT or NEC contract so the responsibilities are written down before anyone is on site. None of that is the domestic MCS scheme, which stops at 50 kWp and does not apply here.

The roof itself gets checked before it carries anything. Many superstore and retail-park decks are profiled metal or a built-up flat roof with a finite remaining service life, and a structural check confirms the deck can carry the additional dead load and the wind uplift on the array before a layout is fixed. Where the roof is approaching recovery, it is usually cheaper to coordinate the solar with the re-roof than to lift a working array off two years later, so we flag that early rather than after the design is set. The drone survey captures the rooflights, the plant and the membrane condition that feed this decision.

Generation is modelled, not assumed. For a roof in this part of the country a south-facing or east-west commercial array is a starting point of roughly 850 to 950 kWh per kWp installed in the first year, at a performance ratio in the region of 80 to 85 per cent once shading, cable and inverter losses are accounted for. Treat those as a modelling starting point we confirm in PV*SOL against your actual roof geometry and orientation, not a guaranteed output. The figure that matters more for a retail site is not the headline yield but the self-consumed share, because a unit used in the store is worth far more than a unit exported, and that share comes straight from your half-hourly meter data rather than a category average.

Format changes the export picture. A grocery or food store that trades long hours and runs refrigeration through the evening will consume a high share of what it makes. A comparison or fashion unit that closes at six and goes dark sheds its load just as the late-summer roof is still generating, so more of that output spills to export at the lower rate. Where the modelling shows that pattern, we look at whether battery storage earns its place by shifting midday generation into the closing hours, and we say plainly where it does not.

An array of this size is a grid connection rather than a plug-in load. Anything over the small-scale threshold needs a G99 application to the distribution network operator, which across Yorkshire and northern Lincolnshire is Northern Powergrid, and the connection terms can shape the design: the network may set an export limit, which on a high self-consumption retail load is often no constraint at all. We start that application early because it runs in parallel with the roof works and is frequently the longest item in the programme.