Battery energy storage systems · hire or buySilent power.Any site.Any scale.
Cut your fuel bill and your generator hours. Battery energy storage for hire and sale, from a 5 kVA unit that runs a welfare cabin to linked batteries that power a whole project as a microgrid.
- Lower fuel costs from week one
- Hire or buy
- Zero diesel on grid or solar
Powering projects for
- VINCI Building
- Careys
- McGoff
- GMI Construction
- Prosperity
- Torsion
Stop paying to run a generator all day
Most site generators are sized for a few seconds of peak load, then idle half-empty for hours, burning fuel. A battery takes the peaks, so you buy far less diesel, or none at all.
Built around the way your industry works
Every site uses power differently. Pick yours to see what we'd typically run, what it replaces and the results we've already delivered.
From one cabin to a whole project
Every battery and hybrid we supply, on one scale, to hire from our rental fleet or to buy. Find roughly where your site sits, and we'll fine-tune the size to your actual loads.
- Pramac SX5 to 10 kVA
- Pramac MX15 to 30 kVA · up to 57.6 kWh
- Pramac LX45 to 60 kVA · up to 96 kWh
- Pramac LX Plus90 kVA · 144 kWh
- Hybrid BESS38 kVA engine · peaks to 240 kVA
- Site battery 225approx. 300 kVA · 225 kWh
- Site battery 449approx. 420 kVA · 449 kWh
- BESS microgridLinked units, no fixed limit
Containerised site battery ratings are approximate continuous kVA at 400 V.
Micro BESS
Compact Pramac batteries for smaller loads that would otherwise keep a generator idling all day. Yours to keep, on site or across your fleet.
- Welfare cabins, offices and lighting
- Single and three-phase, UK sockets fitted
- Solar input on every model
Pramac SX, SX Plus and MX LFP range. Purchase only.
View micro BESS
Site BESS
Hire from our fleet, or buyBattery and hybrid units that take the peak loads of cranes, hoists and plant. Hire from our fleet for a single project, or buy for your own.
- Containerised site batteries225 to 449 kWh, up to around 420 kVA continuous, charges from grid or generator. For hire.
- Hybrid BESS38 kVA Stage V engine and battery in one, peaks to 240 kVA, for sites with no grid supply. Hire or buy.
- Pramac LX and LX Plus45 to 90 kVA LFP batteries, up to 144 kWh, with solar input. To buy.
Microgrid
Batteries linked with your grid supply, generators and solar into one controlled network that powers the whole site.
- Add batteries as the project grows
- Generators only run to top up
- One energy management system
Results from real UK sites
Every figure below comes from a live project we powered. Watch the projects, then read the full stories for the setup, the load and the numbers.
What would battery power save you?
Tell us what you run today. You'll get an instant estimate against diesel, including the battery we'd suggest.
Indicative only, using the same data and method as our full power calculator. Diesel use is based on manufacturer fuel data at 50% load, with generator hire included (Stage V or Stage IIIA rates). The battery figure is a 225 kWh site battery on hire plus, off-grid, a 100 kVA generator at 75% load recharging it for half your running hours (up to 50 a week), or grid electricity at 23p/kWh. Grid connection costs aren't included. CO₂e uses 2.64 kg per litre of diesel (DESNZ). Your quote will be based on your actual loads.
Run your project without burning diesel
Charge the batteries from the grid or from solar and your site can run with no diesel at all. Where there's no supply, a generator only runs to top them up, for a fraction of the hours.
Grid-charged
The battery stores power from even a small supply and releases it at the peaks. No diesel on site.
Solar-charged
Every Pramac LFP unit has a solar input built in, so panels charge the battery directly.
Hybrid
Off-grid, a hybrid BESS's Stage V engine runs only to recharge the battery, at its most efficient load, then switches off.
- Cuts Scope 1 emissions for your ESG reporting
- Supports BREEAM and low-carbon site targets
- No exhaust fumes at the point of use
- Fuel and carbon savings reported throughout the project
Power from people who know sites
WOLFF Onsite is part of the Wolffkran Group, building and running construction equipment since 1854.
- Hire or buyShort-term hire for a single project, or purchase for a permanent fleet or standby system.
- Our own rental fleet and electriciansBatteries we own and maintain, installed by our people, not a subcontracted chain.
- Sheffield and LondonTwo UK bases for faster delivery and site support.
- Proven on major projectsTrusted by VINCI, Careys, McGoff, GMI and more.
Common questions
Can a battery really run a tower crane?
Yes. The battery delivers the short, high peaks a crane needs, and is recharged from a smaller grid supply or generator between lifts. That's how Prosperity ran two cranes from a limited grid connection.
What happens when the battery runs low?
On a hybrid setup a generator starts automatically to recharge it, then switches off. On a grid-connected site the battery tops up from the mains. Either way, power to your equipment doesn't stop.
What's the difference between micro BESS and a microgrid?
Micro BESS is a single compact battery for smaller loads, like welfare cabins and lighting. A microgrid links several batteries with your grid supply, generators and solar into one managed network for large, multi-load projects.
Do I need a grid connection?
No. Off-grid sites use a generator to recharge the battery, running far fewer hours than it would on its own. If you do have a supply, even a small one, the battery can charge from it and remove diesel completely.
What is a hybrid BESS and when would I use it?
A hybrid BESS is a unit that combines a 38 kVA Stage V generator with a lead-carbon battery bank in one container. It suits sites with no grid supply: the battery runs the site and handles peaks of up to 240 kVA, and the engine only runs to recharge it. Several units can run in parallel.
Can I add solar?
Yes. Every Pramac LFP unit has a solar input built in, and solar can be part of any microgrid we design.
Tell us about your site
Send us your setup and we'll come back with a transparent cost comparison and quote within one working day. No obligation.
Request a quote
We never share your details.
Loading the form…
All savings figures are estimates based on typical site conditions and the assumptions stated. Actual results depend on your loads, usage pattern and energy costs. Case study figures are taken from the projects named. © 2026 WOLFF Onsite, part of the Wolffkran Group.