- Client: Mona Energy
- Location: Urban bus depot, Hauts-de-France region (northern France)
- Challenge: Electrify the fleet with own DC infrastructure, optimising contracted grid capacity and making use of the 8+ hour overnight dwell time
- Solution: 5 × Floox Lyra 80 kW, dual connector, 7-metre cables — expansion to 10 units already planned
- Impact: Lower CAPEX vs. 120 kW alternative, reduced fixed grid costs, full charge with time to spare, and positioning as the regional benchmark for zero-emission public transport
Context: electrifying urban transit in northern France
Mona Energy is a French mobility and energy services operator active in the Hauts-de-France region — one of the most active urban transit corridors in northern France. A combination of the EU AFIR regulation, municipal decarbonisation targets and rising diesel costs accelerated the decision to install owned DC charging infrastructure at their main depot.
The site is well suited to overnight charging: buses return to the depot at the end of each service day and remain parked for over 8 hours before their next shift. That window is the foundation of the entire technical and commercial case for this project.
Site characteristics
- Fleet-only depot with planned rotations and regular overnight dwell periods
- Medium-size electric bus fleet with standard CCS2 charging ports
- Guaranteed overnight charging window of over 8 hours
- Variable distances between parking bays and charger positions — a key driver in cable length specification
Why act now?
- AFIR Regulation: mandates own charging infrastructure at passenger fleet depots
- Hauts-de-France regional decarbonisation incentives for sustainable mobility investment
- Dependency on third-party public chargers: high and unpredictable cost per session
- Growing demand for zero-emission transport contracts from regional municipalities
The challenge: getting the specification right from day one
The biggest risk in fleet electrification projects is not underspecifying — it is oversizing: paying for hardware capacity that will never be used and locking in a higher contracted grid tariff every single month. Mona Energy came to the initial conversation expecting 120 kW chargers, the option the market typically presents as the “safe” choice.
A joint technical analysis with the Floox team demonstrated that real operational data pointed in a different direction: with over 8 hours of overnight dwell time, an 80 kW charger — or even two buses sharing a dual-connector unit at 2 × 40 kW — delivered a full charge with time to spare. Oversizing was not just unnecessary — it was costly on two fronts simultaneously.
The hidden cost of oversizing
Installing 120 kW chargers in a depot with 8-hour dwell windows means 40–50% of installed capacity is never actually used. And that oversizing is not free — you pay for it twice. First in the unit price of the charger, which rises with power rating. Then every month, in the contracted grid capacity charge — the fixed line on the electricity bill whether the charger is running at full load or not.
The solution: Floox Lyra 80 kW — the intelligent choice
Following the real-use analysis, Floox specified 5 × Lyra 80 kW units with dual connectors and 7-metre cables. Choosing 80 kW over 120 kW was not a compromise — it was the technically correct specification for this site.
- Model: Floox Lyra 80 kW
- Configuration: Dual connector — 2 × 40 kW simultaneous or one bus at full 80 kW
- Cable length: 7 metres, comfortably reaching every bus charging port across the depot layout
- Units installed: 5 (full fleet coverage within the overnight window)
- Planned expansion: 10 units in total to support fleet growth
- Compatibility: CCS2 (Combo 2) — European standard for medium electric buses
- Connectivity: OCPP — integrated with the Floox management platform
Why 7-metre cables?
Bus depot layouts are not uniform. Short cables leave some bays unreachable or force additional manoeuvring. At 7 metres, each Lyra unit reaches the charging port of any bus within its coverage radius — no repositioning of vehicles, no depot modifications required.
80 kW vs. 120 kW: the analysis that changed the decision
| Criterion | Lyra 80 kW ✓ Selected | 120 kW alternative |
|---|---|---|
| Hardware unit cost | Significantly lower | Higher price per unit |
| Contracted grid capacity required | Lower — fixed monthly network charge | Higher — fixed charge whether used or not |
| Match to overnight dwell window (8 h+) | Full charge delivered with time to spare | 4–5 hours of installed capacity left idle |
| Real utilisation of installed power | High — capacity matched to actual use | Low — 40–50% chronically underutilised |
| Total CAPEX (5 units) | Lower initial investment | Higher investment with no operational benefit |
| ROI | Faster payback — savings on two fronts | Slower payback — double penalty |
Implementation: zero downtime, built to scale
All installation phases were scheduled around the fleet’s service shifts, ensuring buses remained fully operational throughout the project. Floox coordinated directly with the local certified installer and Mona Energy’s technical team from day one, covering everything from engineering design to OCPP integration and staff training.
Installation process
- Pre-engineering: depot layout analysis, distance mapping and installation point definition to maximise 7-metre cable coverage
- Civil works: conduit routing and connections — no structural changes to the depot, no operational bays affected
- Installation & commissioning: 5 Lyra units mounted, wired and configured; OCPP integration with the Floox platform and functional testing on live vehicles
Built to scale from day one
The electrical infrastructure and management backoffice were sized from the outset to support 10 chargers. The planned expansion — already agreed to meet fleet growth — will not require changes to the management platform or main switchboard. New units simply connect into the existing system. This future-proof approach was a decisive factor for Mona Energy.
Project economics: from scepticism to ROI
The economic case for right-sized overnight charging in public transport fleets is particularly strong. Savings materialise on two lines simultaneously: lower upfront investment and lower recurring network costs. Both contribute to a shorter payback and better long-term return.
Lyra 80 kW
units installed
Units in the
planned expansion
Overnight dwell
window available
Battery state at
start of every shift
Cable — full
depot coverage
Break-even point
The dual cost reduction — lower CAPEX per unit versus 120 kW and lower contracted grid capacity month on month — significantly shortens the amortisation period. With systematic overnight charging across the full fleet, the return is robust and predictable from the very first month of operation. The argument is straightforward: you pay less to install and you pay less every month to run.
Cumulative savings (vs. public charging)
0€10k€20k€30k€
JulAugSepOctNovDecJanFeb
Upward trend as operations mature
Energy dispensed (MWh / month)
05 MWh10 MWh15 MWh
JulAugSepOctNovDecJanFeb
Stable volume across full overnight charging cycles
Charging sessions vs. Energy
03570
07.5 MWh15 MWh
JulAugSepOctNovDecJanFeb
SessionsEnergy
Regular high-capacity sessions — deep overnight charging pattern
Growing cumulative savings · stable and increasing energy volume · regular high-capacity sessions consistent with systematic overnight full-charge cycles.
Business impact: more than a charger
The installation has transformed Mona Energy’s operational model. The depot has evolved from a passive parking facility into a smart, autonomous energy infrastructure that guarantees full fleet availability every morning — with no dependency on third-party networks.
Fleet always ready
Every bus starts its shift at 100% charge — no reliance on third-party infrastructure or availability
Dual savings
Lower upfront CAPEX and lower fixed monthly network costs — savings working on two fronts at once
AFIR compliance
Own infrastructure, fully documented and auditable in real time via the Floox management platform
Planned growth
Expansion to 10 units with no changes to platform or main switchboard
Regional benchmark
Mona Energy positioned as the reference operator for zero-emission urban transit in Hauts-de-France
Results
- ✓Correct technical specification from the outset: 80 kW proven to be the optimal choice for 8-hour overnight dwell windows, with no performance compromise whatsoever
- ✓Reduced total CAPEX versus the 120 kW alternative, with lower contracted grid capacity and greater investment efficiency across the full fleet
- ✓100% autonomous depot operation: the entire fleet charges every night with no dependency on third-party infrastructure or availability risks
- ✓AFIR regulatory compliance secured with own infrastructure — scalable and ready for the already-planned expansion to 10 units
- ✓Mona Energy consolidates its position as the reference fleet electrification operator in the Hauts-de-France region
