Warehouse solar: match the array to the load profile

Roof area is only the start

A large warehouse can have limited daytime demand, while a smaller site can have refrigeration, processing or charging loads. Begin with electricity data and operating reality, then test generation against demand. Request intervals showing generation, onsite use, export and import.

Half-hourly data reveals weekday, weekend and seasonal patterns hidden by an annual bill. Include shifts, holidays, cold storage, HVAC, forklifts, vehicle charging and planned expansion. Confirm which meter serves each building.

Data quality matters. Check that the interval period covers representative operations and that estimated readings, temporary shutdowns or a recent tenancy change have not distorted the baseline. Ask the energy manager to annotate unusual weeks and planned process changes before the model is accepted.

A warehouse may have high demand at night but strong solar production during the day. That does not automatically make solar unsuitable: direct use, storage, export and operational changes can all be assessed. It does mean a model based only on annual consumption is not enough.

Separate baseload from flexible loads. Refrigeration and ventilation may run continuously, while charging, hot-water production or some processing can be scheduled. Any operational change needs an owner and a practical control plan; it should not be counted as a saving merely because the spreadsheet assumes it.

Plan operations and safety

A project can affect loading bays, traffic, fire systems, roof access and emergency procedures. The plan should identify isolation, working-at-height controls, deliveries and disruption. Roof condition, loading, waterproofing, skylights, cable routes and inverter access need appropriate assessment.

Coordinate the programme with peak trading periods and planned roof maintenance. Decide how contractors will enter the site, communicate with the control room and protect stock. Include temporary loss of parking, loading or production in the business case instead of describing the installation as disruption-free.

The handover should include a single-line diagram, isolation points, monitoring credentials, maintenance instructions and an emergency contact route. Train facilities staff on what the equipment does and what they must not isolate or reset without the right procedure.

Test storage and export

A battery’s value depends on capacity, power, controls, cycles and the contract. Confirm the DNO position and supplier export arrangement. Compare solar-only, export-control and storage options using the same load data, degradation, downtime and maintenance assumptions.

Storage can support peak reduction or time-shifting, but it has conversion losses and operating limits. Ask whether it is intended to reduce import peaks, increase self-consumption, provide resilience or participate in a market service. Each objective changes the controls and the economic test. Confirm who can change those controls and whether a service provider takes a share of any resulting value.

Export should be modelled as a physical and commercial constraint. State the maximum export, the price assumption, curtailment rules and the consequence of a controller fault. Review the model again if production, refrigeration or charging loads are expected to grow.

Common questions

How much roof should be covered?

It depends on structure, safety, demand, network capacity, roof condition and economics; maximum panels are not automatically best.

Why use half-hourly data?

It shows when the site imports, supporting realistic self-consumption, export and storage modelling.

Can panels go over skylights?

The safe layout must preserve daylight, roof integrity, maintenance and emergency requirements.

Sources and further reading

• Carbon Trust guides
• HSE work at height