Solar generation and battery storage can support fleet charging, but they solve different problems. Solar supplies energy when sunlight is available. A battery shifts energy in time or supplies additional power for a limited period. Neither should be added to a depot simply because charging and storage can be shown in the same diagram.

Start by identifying the constraint. Is the depot buying expensive electricity, exceeding a site power limit, charging after solar production has ended or preparing for a defined interruption? Each objective requires a different system design and financial comparison.

Match solar production to vehicle presence

Rooftop solar may serve building loads while delivery vehicles are away. That can still have value, but it should not be described as direct solar charging of those vehicles. The charging benefit depends on the overlap between generation and charging demand.

Use a time-based model of solar production, facility consumption and vehicle sessions. Annual solar output alone cannot show how much energy will reach the vehicles. Seasonal weather, export arrangements and non-charging site loads affect that result.

A depot with vehicles parked during daylight may be able to use solar directly without a battery. If vehicles mostly return after sunset, storing some daytime generation may be useful, but its value must be compared with exporting energy or simply using the grid.

Distinguish battery power from battery energy

Battery power, expressed in kW, determines how much demand it can support at a given time. Battery energy, expressed in kWh, determines how long that support can continue. A system needs both characteristics to match the depot's task.

Consider an illustrative site that wants 120 kW of charging power for two hours while allocating only 80 kW of grid input to charging. Ignoring conversion losses and other loads for the initial illustration, storage would need to supply a 40 kW difference and 80 kWh over that period.

Actual selection must allow for usable capacity, conversion losses, reserve policy, ageing and recharge conditions. An 80 kWh nameplate battery should not be assumed to deliver 80 kWh of usable energy to the chargers. Likewise, sufficient energy capacity does not establish that the system can sustain the required power.

Check how the battery recharges

Peak support is repeatable only if the battery can recover its energy before the next required session. The charging schedule must therefore include battery recharge alongside vehicle charging and facility loads.

If the site already uses all available grid energy each day, a battery cannot solve that persistent energy deficit by cycling the same limited supply. The project may need more charging time, another energy source or a connection upgrade.

The EVB overview of fleet charging with optional solar and storage is useful for opening this discussion with a supplier. A project proposal should quantify the charging task and identify the proposed battery's usable output, control arrangement and recharge window.

Compare storage against simpler alternatives

First assess whether staggered charging, a different AC and DC mix or a revised route schedule can meet the need. Those changes may cost less than installing and operating a battery. Storage becomes more compelling when a specific power constraint or tariff opportunity remains after workable scheduling options have been considered.

Use the actual electricity tariff and a realistic dispatch model. Battery cycling introduces losses and wear, so an apparent difference between cheap and expensive electricity periods is not the entire business case. Service costs, replacement assumptions and financing also matter.

Do not combine several benefits without checking that their operating requirements are compatible. Energy reserved for emergency use cannot also be spent on routine peak reduction unless the reserve policy allows it. The same stored energy should not be counted twice in the financial model.

Treat backup operation as a separate capability

A grid-connected solar and storage installation does not automatically keep charging during a power outage. Backup operation requires a suitable electrical architecture, protection, switching and controls, with a clear definition of which loads remain supplied.

If continuity is a purchasing objective, request a documented outage operating mode and an acceptance test for the required loads. Confirm how the system transitions, what charging power remains available and how long the reserved energy supports that duty.

Solar and storage are justified when the proposal shows a measurable contribution to the depot's operating problem. The strongest design may include both, one or neither. Choosing the appropriate scope protects the fleet from paying for capacity that does not improve its charging schedule.