Alectrona
Battery form factorOnce a commercial battery passes a certain size it stops being a cabinet in a plant room and becomes an outdoor enclosure on its own base. The form factor is an engineering decision that sets where the system goes, what it stands on, and how it sits next to your building.
A commercial battery has to live somewhere. For a smaller system that can be a wall-mounted or floor-standing cabinet inside an existing plant room or switch room. For a larger one, measured in hundreds of kilowatt-hours up to the megawatt-hour range, it is usually a factory-built outdoor enclosure: an adapted ISO-container or a purpose-built cabinet that arrives weatherproof, pre-wired and tested, with its own thermal management, fire detection and the battery management system inside.
This page is about that choice of housing. How big the battery should be is a separate question. The capacity question is a separate exercise, covered on sizing. Here the question is what the system is built into and where it physically lands on your site, because that drives the foundations, the fire separation, the noise and the planning route long before the first cable is pulled.
Brand-agnostic: the bankable battery that fits the project.
The cells and electronics inside are broadly the same family across the formats. What changes is the package they ship in, and that follows scale.
The split is not arbitrary. As the energy rises, putting the battery inside an occupied building gets harder to justify on fire separation and space, so the system moves outdoors and the enclosure takes on the protection the building used to provide.
A wall-mounted or floor-standing unit sited inside an existing plant room, switch room or back-of-house area.
A self-contained weatherproof unit, or a larger walk-in container, that stands outside on its own base and arrives factory-tested.
The strongest argument for a containerised or pre-built outdoor unit is that the integration happens in a factory rather than in your car park. The cells, racks, power conversion, thermal management, detection and the battery management system are assembled, wired and tested together as one product before it ever reaches the site.
That means the high-risk integration work is done in controlled conditions and verified before delivery, and what arrives is a known quantity that is craned into position and connected. Site work reduces to the civils, the grid connection and the commissioning checks, rather than building the whole system in the open. It also makes the unit a defined product to assess, which is cleaner for both the fire strategy and the network connection than a system improvised from loose parts on site.
Choosing the form factor is really choosing where the system lives and what has to be true of that spot. An outdoor or containerised unit brings its own set of site requirements.
An indoor cabinet trades these for a different list: floor loading, the room's fire compartmentation, ventilation and a viable cable route to the distribution board. Either way, the housing is what fixes the constraints, which is why it is decided early.
An outdoor battery is not silent. The thermal management, the cooling fans or HVAC and the power electronics make noise, which matters where the unit sits near a boundary, a residential neighbour or a quiet workplace. Where it is relevant, the noise is assessed and the unit is sited and screened to suit, rather than positioned on convenience alone.
The form factor also shapes the planning route. A large outdoor enclosure is a visible structure on the site and may engage planning and environmental requirements that an indoor cabinet inside an existing building does not. We treat that as part of the design rather than an afterthought. The detail of the consent route, the noise assessment and the fire strategy each have their own page: see planning for the consent side and fire safety for detection, suppression and separation. This page is about choosing the box; those two are about clearing it.
A factory-built enclosure is only as trustworthy as the certification that travels with it, and the relevant standards reach beyond the cell. IEC 62619 covers the safety of the industrial lithium cells and the battery management functions inside, and we treat its certificate as a baseline rather than a selling point. Above that, IEC 62933 is the standard series for electrical energy storage systems, with IEC 62933-5-2 dealing specifically with the safety requirements for grid-integrated systems, so it speaks to the enclosure as an installed product rather than to the cells alone. For a complete unit, UL 9540 is the listing standard for the energy storage system as a whole, and UL 9540A is the large-scale fire-propagation test that informs separation distances and the protection around the unit.
None of this is a marketing badge. It is documentary evidence we ask the supplier to produce for the specific product before contract, and it feeds straight into the fire strategy and the network application. The detail of how thermal-runaway risk is managed sits on the fire safety page, and the chemistry choice that drives it on the LFP and NMC comparison.
A containerised unit is a piece of plant, and getting it onto your site is a logistics exercise in its own right. A full ISO-container enclosure travels as an abnormal or heavy load, which means the delivery route, any low bridges, weight-restricted access and the swing room for the crane all have to be checked before a date is fixed. The lift itself is a planned operation under the Lifting Operations and Lifting Equipment Regulations 1998, with a lift plan, a competent appointed person and an exclusion zone while the unit is set on its base, and the whole site runs under CDM 2015.
We establish the access and lifting picture early with the in-house insured drone survey, so the delivery and crane positions are designed in rather than discovered on the day. The longest pole in the programme is rarely the enclosure. It is usually the grid connection: the Distribution Network Operator application under G99, and any network reinforcement it triggers, set the timeline more than the kit does, which is why we open that conversation first. The mechanics of that are on the G99 application guide and the grid connection queue guide.
One advantage of a modular, factory-built format is that it is designed to grow and to be serviced as a product rather than as a fixed installation. Lithium cells lose capacity across their working life, so a system meant to hold a defined energy figure for years is often specified with augmentation in view: adding racks or modules later, or sizing the early years with the known fade allowed for, rather than oversizing on day one. A containerised enclosure with standard rack architecture makes that practical, and it makes warranty and end-of-life cleaner too, because the unit is a defined product whose modules can be serviced or swapped.
Disposal at end of life falls under the Waste Batteries and Accumulators Regulations 2009 and the wider duty of care for waste, which a reputable supplier and installer plan for from the outset rather than leaving as a problem for later. How the long-term economics of holding that capacity stack up is a question for the battery costs and return page, not a number we will promise here. The figure is modelled against your tariff and dispatch, with the basis disclosed. Whichever housing you land on, the form factor is chosen as part of the engineering, alongside the sizing of the system itself.
It is a commercial battery built into a walk-in or step-in outdoor enclosure, often an adapted ISO-container or a purpose-built equivalent. The cells, power conversion, thermal management, fire detection and the battery management system are assembled and tested inside it at the factory, so it arrives as a complete weatherproof unit that is craned into position and connected on site.
It is the usual format for the larger commercial systems, from hundreds of kilowatt-hours into the megawatt-hour range, where putting the battery inside an occupied building is harder to justify.
It follows the size of the system and the space you have. A smaller battery can sit in an indoor cabinet or rack in a plant room, drawing on the building's own fire compartmentation and ventilation. A larger one usually moves to an outdoor cabinet or a containerised unit that carries its own thermal management and protection.
The deciding factors are the energy and power the system needs, whether there is suitable indoor space, and the fire separation the building can support. We settle the capacity first on the sizing exercise, then choose the housing that fits the site.
A designed base and the room to work around it. A loaded container or cabinet is heavy, so it needs a reinforced concrete pad or piled foundation, set level and able to carry the unit and the crane loads during the lift. It also needs a delivery and lifting route in, clear working space at the doors and service panels, and a separation distance from buildings and boundaries set by the fire strategy.
These requirements are part of the design from the start, because the housing fixes the siting before any cabling begins.
It is not silent. The cooling and thermal management, fans or HVAC, and the power electronics produce noise, which matters where the unit sits near a boundary, a neighbour or a quiet workplace. Where it is relevant we have the noise assessed and the unit sited and screened to suit, rather than positioned on convenience.
Noise is also one of the things the planning route looks at, which is covered on the planning page.
A large outdoor enclosure is a visible structure and can engage planning and environmental requirements that an indoor cabinet inside an existing building does not. Whether consent is needed, and what it involves, depends on the site, the location and the scale of the system.
We treat the consent route as part of the design rather than an afterthought. The detail sits on the planning page, and the fire detection, suppression and separation that travel with the enclosure are on the fire safety page.
There is no honest per-container figure, because the cost is set by the energy and power you specify, the foundations and crane the site needs, and the grid connection, not by the box itself. A containerised system carries civils, a designed base and an abnormal-load delivery that an indoor cabinet does not. We price it survey-led after the design is settled. Background sits on battery costs and commercial solar cost.
The enclosure is rarely the long pole. Factory build and delivery of a containerised unit run to a defined lead time, but the date that usually governs the programme is the grid connection: the G99 application to your Distribution Network Operator, and any reinforcement it triggers. Foundations, the planned lift and commissioning then follow. We give an indicative programme after the survey and open the connection conversation first.
We model your half-hourly load and your solar against a battery sized from an on-site survey, so the figure you get is yours, not a from-price. Capex first, with the bankable brand that fits the project.