Construction Battery Energy Calculator
⚡ Construction Battery Energy Calculator

How much is your
generator costing you?

Construction sites could save up to £50,000 a year by switching from diesel to battery electric. This calculator works out your site's exact figure — then shows you what the switch looks like. No jargon. Just the numbers.

£30–80k
Typical annual diesel bill,
100–200kVA generator
2 yrs
Typical BESS payback
vs ongoing diesel cost
DIESEL GENERATOR
1
2
3
What are you powering?Generator setupYour results
What are you powering?
Each application has a different load pattern — tell us which fits best. You can always adjust the numbers on the next page.
🏗️
Tower Crane
High peaks, low average — classic BESS territory
🏢
Site Office
Steady all-day load — lighting, computers, welfare
🧱
General Construction
Mixed tools, equipment and plant on a working site
EV Plant Charging
Electric dumpers, telehandlers, compact plant
Your generator setup
Move the sliders to match your site. We've pre-filled based on your application type — adjust if needed.
Generator Size
120 kVA
20 kVA500 kVA
Running hours per day
10 hrs
4 hrs24 hrs (continuous)
Typical site load (% of rated capacity)
25%
10% (barely ticking)90% (flat out)
⚠️ Below 25% load — this is the wet-stacking zone. Fuel efficiency is about twice as bad as it should be, and you're accelerating engine wear. This is very common and very expensive.
Diesel price per litre
£1.28
£0.90£1.80
Default: UK commercial diesel average, May 2026
How long does the site run? (total duration)
6 months
1 week2 years
ℹ️ We'll show you both total project costs and annualised figures — so the numbers are useful whether you're planning a short contract or a long-term site.
Your estimated diesel cost — this project
£0
Based on your inputs
Annualised spend
£0
per year if this site ran for 12 months
Could you go 100% battery?
☀️
Calculating...
0
Litres / Year
— litres/day
💰
£0
Annual Saving
— fuel reduction
🌍
0t
CO₂ Saved / Year
⚡ Recommended Allye System
Payback Period
vs annual diesel saving
Key assumptions: Generator fuel efficiency varies with load factor — at 25% load, a diesel genset burns ~0.42 L/kWh, almost twice as inefficient as 75% load (0.27 L/kWh). This is the biggest lever in the calculation. CO₂ factor: 2.68 kg/litre (DEFRA 2024). Payback based on Allye installed cost at £550/kWh and fuel saving only — does not include generator hire, maintenance, or fuel price inflation. Lifetime saving over 15-year BESS life.

🔋 Answering the questions you probably have

✓ No ADR Required — Allye systems
ADR (Agreement on Dangerous Goods by Road) is a European regulation governing the transport of hazardous materials — including large lithium battery systems. Most BESS on the market require ADR-compliant transport: specialist vehicles, trained drivers, paperwork. This adds cost and complexity every time the system moves.

Allye's systems are specifically designed so that transport does not trigger ADR requirements, meaning they can be moved using standard vehicles and drivers. This is a significant operational advantage for construction sites where the BESS needs to follow the project.
The BESS charges from whatever power is available — grid connection, solar, or even the generator itself (in hybrid mode). On a site with a grid connection: the BESS charges overnight at off-peak rates, then powers the site all day. On a fully off-grid site: a much smaller generator runs at a constant, efficient load to keep the BESS charged — the BESS handles all the peaks and variable loads. Typical charge time: 4–8 hours depending on system size and charge rate.
Yes — Allye systems use Lithium Iron Phosphate (LFP) chemistry, which has a significantly higher thermal stability threshold than other lithium chemistries. LFP doesn't undergo thermal runaway in the same way as NMC or NCA cells. All Allye units include a Battery Management System (BMS) that monitors cell temperature, state of charge, and health in real time, cutting power if anything goes wrong.

UK guidance from the NFCC recommends a 10-metre separation distance for larger BESS deployments. Engage your local Fire and Rescue Service for larger installations. Standard BS 7671 electrical connection requirements apply.
The system is sized to prevent this — your BESS energy capacity is calculated with a margin above your expected daily load. The Battery Management System will warn you well before reaching the lower discharge limit. In hybrid mode, the generator kicks in automatically to recharge before this point. For full-replacement mode, standard practice is to charge the BESS overnight so you start each shift with a full battery.
Yes. This is one of the strongest use cases for BESS. A tower crane's hoist motor might draw 150–250 kW for a 30-second lift, but averages just 10–15 kW across a shift. A conventional generator has to be sized for the peak — meaning it runs at 5–10% load most of the day, burning fuel and wet-stacking. A BESS stores energy during the idle periods and discharges it instantly for each lift. This is called peak-shaving and it's where the numbers get interesting.
Much less than a generator. No engine oil, no fuel filters, no cooling water, no exhaust systems. LFP battery cells are highly stable and the main maintenance tasks are: software/firmware updates (remote), periodic visual inspection, connection checks, and thermal management system servicing. Allye provides remote telemetry and monitoring as standard. Typical O&M cost: 1.5–2% of installed cost per year.

Get Your Accurate Quote

Fill in your details and a specialist will contact you with a site-specific assessment, accurate pricing, and payback analysis. No obligation.

All figures are estimates for indicative purposes. Fuel efficiency based on published diesel genset curves. CO₂: DEFRA 2024 (2.68 kg/litre). Payback based on £550/kWh installed cost and fuel saving only. Actual site conditions vary.

⚡ Ask about battery storage
For site managers, project managers & procurement teams
SilentSite Assistant
Hi there. Ask me anything about battery storage for construction sites — how it works, how it charges, transport, safety, costs, tower cranes, planning. Whatever you need to know.