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The full system has over 15 key attributes, including the storage cells, the control systems, the housing, and the operation. Our system is an automated energy control system that takes and manages power from multiple sources and regulates power to where it is needed.  We provide the hardware, the software and the know-how to make using energy as efficient as possible.

We supply proprietary energy storage systems from a few kW up to 1 MW.  We also undertake special projects and can build systems above 1 MW.

A Firefly system is the result of over 10,000 hours of R&D and provides you with an engineered solution that has been manufactured to the highest standards to get the maximum out of the technology. Designed and built at our factory in the UK (who says UK manufacturing is dead?) by our team of highly skilled engineers, we manage a supply chain of over 150 companies and 1,000 components in each system.


Energy Storage Systems require cells of some kind to store the electricity. There are many choices, each with different pros and cons.  The two technologies most widely used are Lithium Ion and Lead Acid.  Each of these has further refinements according to the intended end use.
Lithium Ion is lighter, has higher energy density (kW/kg), has much better performance over time and can cope with higher temperatures.  It also has a flat-line output meaning the lights don’t dim until the end, but it is more expensive and requires more sophisticated controls to get the most out of it. Firefly units are available with LFP lithium technology.
Lead Acid has been around in various forms and flavours for many years.  It’s cheap, it’s effective but it does have some drawbacks.  It’s heavy, it doesn’t cope well above 25°C and has a declining output, meaning the lights gradually dim as the storage depletes.  But it is relatively cheap and managed correctly, is very viable as a cell type. Firefly units are available with both OPzV and AGM lead acid technologies.

There are many others and many more future chemistries will arise as cell manufacturers push for ever greater performance and lower costs. Firefly continually appraises available technologies and uses those which provide the best balance between cost, reliability and performance.


The cells need to be connected together.  Simply running cables around works, but only up to a point.  To really get the most out of a system, the cable layouts must be optimised, lengths matched so as to balance thermal and electrical performance.  Doing this across many batteries is complicated.

Battery Management System

Managing the cells so that they are charged and discharged in an orderly fashion allows you get the most life and performance out of them.  Imbalances between cells causes unwanted stresses in the system and so efficient deep system monitoring is required.  This also prevents overloading and misuse of the unit. Firefly’s LFP equipped models feature ACTIVE BMS: an industry leading Active Battery Management System, while our CARE BMS system is employed for Lead Acid models.

Climate Control

Battery cells have an optimal temperature range.  One way to keep them within this range is to assemble them in a big air conditioned room, however the power required to run the air conditioning is defeating the purpose of the efficient energy management.  Elevated temperatures have immediate and long term effects on the cells, leading to faster degradation.  So managing the internal environment is critically important.  Firefly CLIMATE MASTER automatically manages the air handling system that minimises parasitic loads and maintains temperature below critical levels.

Power Conversion

Batteries store power in DC.  Most applications use AC power.  Like anything else there are many suboptimal repurposed systems available that claim to be able to convert DC to AC power.  Firefly uses purpose built, high power inverter technology which is capable of high loads and high thermal cycling without loss of power. This is an industry-best level of efficiency.


Inputs from the grid, the diesel or gas generator and solar panels or wind.  Each input has different characteristics and need to be both physically connected and marshalled appropriately by the system.

Diesel Fuel Save Controller

Our Control system is designed to talk to any diesel, gas or other fuel powered generator with auto-start functionality. We can interface with all standard control systems including ComAp and Deep Sea Electronics.  This means that the Firefly system can decide when the diesel generator should run and for how long.  With a typical diesel generator, our system will run for 60-70% of the week whilst the generator is off.

Solar Charge Controller

Our solar charge controller systems mean you can connect a photovoltaic (PV) solar array directly into the Firefly unit, saving on the cost of the solar inverter and increasing the electrical efficiency.  Taking the solar power in via our charge controllers means less cost and greater control and reliability.  In some scenarios We can interface with existing PV inverters if, say, our system is being retrofitted to a solar installation.  This is known as AC coupling.


There needs to be a means of connecting external power sources to the ESS.  Firefly systems come with AC and DC isolators, plugs and sockets are required.  It has already been thought about designed and implemented.


Energy storage systems need to be connected to the loads.  As with the incoming connectors we provide all the outgoing connectors, circuit breakers, plugs and sockets, already designed and available.  You can have single phase or three phase or you can change this on the front of the unit.  We have anticipated what the requirements are and built the system accordingly, for maximum operability.

Programmable Timed Outputs

We have gone beyond simple outputs with our programmable output functionality.  Either built-in, or using our Timed Distribution Unit, the output of the Firefly units can be split across multiple circuits (typically in groups of 6) and each circuit switched on and off as per your required schedule. This enables you to easily automate the switching off of some circuits whilst keeping others on, which allows you to control and prioritise the loads in your site or building whilst preserving usability. Each circuit can have multiple schedules to account for daily and weekly activities.  So you can switch off the non-critical circuits, leaving on only those must have services, like the alarms, CCTV,  security lighting, or servers but not the air conditioning which needn’t run when there is no one around.  This works as a Building Energy Management System (BEMS).


Each Firefly system has a purpose-designed housing, be it a permanent installation with fixed connections or a unit intended for temporary applications which will be moved on a regular basis by forklift or crane. We provide the appropriate chassis, canopy, lifting and transport features needed to ensure the units are as practical and safe as possible. For larger units we provide our systems in customised ISO shipping containers.

Monitoring and Reporting

Our Glow platform provides you with comprehensive data on each of your machines wherever they are. Glow allows you to see the machines individually or in aggregate so you can see and report on the energy savings quickly and accurately. Glow is hosted on enterprise level servers with tier one security and full redundancy.


Each Firefly system is designed to be connected to our cloud based monitoring platform. This means that we can access machines remotely anywhere in the world and run diagnostic checks and adjust system parameters if required.

We also have a dedicated team of Field Service Engineers who provide training for setup and operation, support for your own servicing and to attend site in the event of corrective maintenance. This gives you the peace of mind that your investment will be fully supported and able to deliver the highest financial rates of return.

End of life

When your system finally reaches the end of its life or the battery cells are below the required level of performance, we will take the system back and recycle it.  We will endeavour to repair and/or refurbish a unit because that is the most sustainable and environmentally responsible thing to do.  But when there are no other options available, we will take the unit back and recycle it; end to end support as part of a circular economy.

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