Charge RosterThe problem is not the number of EVs. It is the overlap in charging need.
A workplace can have ten EV drivers and three chargers without having a serious capacity problem. If most drivers need only part of the day to charge and their needs occur at different times, those three chargers may serve many vehicles.
The opposite can also be true. A workplace may have several chargers and still frustrate employees if everyone needs them at the same time, cars stay in charging bays long after charging is useful, or nobody can see when a charger will become available.
So start with a different question:
How often does a driver need workplace charging and fail to get a usable charging period?
That is more informative than simply comparing the number of EVs with the number of plugs.
Diagnose which bottleneck you actually have
Several different problems can all look like “we need more chargers”.
| Bottleneck | What it looks like | First response |
|---|---|---|
| Peak-time overlap | Everyone wants to charge after arriving in the morning | Spread demand across the workday where practical |
| Long occupancy | Cars remain in charging bays much longer than they need charging access | Use defined charging turns and clear end times |
| Unused reservations | Booked time stays unavailable after a driver changes plans | Make cancellation easy and return time to the schedule |
| Poor visibility | Employees repeatedly check chargers or message colleagues | Give everyone one shared view of availability |
| Parking friction | A finished vehicle blocks the physical charging space | Define when vehicles should move and who owns enforcement |
| Electrical constraint | The site cannot deliver enough simultaneous power | Involve the installer/electrical team and assess load management or supply |
| Genuine charger shortage | Valid requests remain unserved even after reasonable sharing | Plan additional charging capacity |
Do not use a scheduling tool to disguise an electrical problem. Equally, do not treat every scheduling problem as proof that another charger must be installed.
Measure charging time, not just charger count
A charger is available for many hours during a working day. That time can often be shared between more than one vehicle.
For example, four chargers available for eight hours provide 32 charger-hours of theoretical access. If most drivers need around two hours of workplace charging, the important question becomes when those two-hour needs occur and whether employees can use different periods.
The US Department of Energy's Alternative Fuels Data Center lists several established workplace-sharing approaches, including assigned charging buddies, reservations and time limits. The common idea is the same: when chargers become constrained, access can be managed as a shared resource rather than one car occupying one charger for the whole day.
See the DOE workplace charging guidance
Fix the avoidable losses first
Before approving a hardware expansion, look for charging time that already exists but is hard to use.
1. Make availability visible
Employees should know when a charger is expected to be available without walking to the car park or starting a message thread.
A shared schedule turns the day into visible charging periods rather than a set of plugs that may or may not be occupied.
2. Use realistic charging durations
If a driver normally needs two hours, reserving the charger for an eight-hour workday removes six hours from everybody else.
A maximum duration can help, but it should reflect real commuting and charging needs rather than an arbitrary rule.
3. Return cancelled time immediately
A cancelled charging turn should become available to other drivers. Unused time is capacity that already exists.
4. Make the end of a charging turn clear
A schedule is useful only if drivers understand when the shared resource should become available again. Workplace rules should explain what happens when a charging turn ends and whether the vehicle needs to move.
5. Decide what happens when everything is full
A workplace can use another available period, a waitlist, a queue or another site depending on how employees work.
A queue answers who is next. A reservation answers when do I get to charge. They solve different planning problems.
ChargePoint, for example, uses a waitlist model for busy shared stations and reports that its waitlist customers have seen effective station utilisation increase where demand was already high. That is a hardware-connected implementation, but the operational lesson is broader: visibility and an explicit allocation process reduce the scramble around scarce charging access.
Read ChargePoint's workplace waitlist explanation
Use unmet demand as the expansion signal
High utilisation is not the same as insufficient capacity. A charger that is busy most of the day may simply be doing its job well.
The stronger signal is unmet demand:
- a driver needs charging during the working day;
- no suitable charging period is available;
- the need cannot reasonably move to another available time;
- and the same pattern happens repeatedly.
Track at least:
- which days and periods run out first;
- how much charging time drivers were trying to obtain;
- whether alternative periods existed;
- how often cancellations returned useful capacity;
- whether the shortage is growing over time.
This turns “the chargers always feel busy” into evidence that can support an infrastructure decision.
When should you add another charger?
Additional hardware becomes easier to justify when several conditions are true at once:
- valid employee charging needs are repeatedly left unserved;
- existing chargers already use sensible charging durations;
- unused bookings are being returned to the schedule;
- employees can see and use alternative periods where those alternatives are practical;
- the same peak shortage continues across multiple days or weeks;
- the number of employees depending on workplace charging is increasing.
At that point, the next decision is technical as well as operational. A qualified installer or electrical professional should assess charger power, site supply, load management, cabling, parking layout and installation cost.
A simple decision sequence
- Map demand: who needs workplace charging, on which days, and at what times?
- Expose availability: can employees see the charging time that already exists?
- Tighten sharing: are bookings, time limits, cancellations and end-of-turn rules sensible?
- Record misses: which legitimate requests still cannot be served?
- Separate electrical and scheduling constraints: is the shortage plugs, power, parking, or coordination?
- Expand when the evidence stays red: add capacity when reasonable sharing no longer solves the recurring shortfall.
Where Charge Roster fits
Charge Roster is designed for the coordination stage after workplace chargers already exist. Employees see available charging times and reserve access, while the workplace can see the shared schedule and requests that the schedule could not accommodate.
That does not create electrical capacity and does not control the charger hardware. It helps answer the operational question that comes before a hardware decision: can the chargers we already have serve more people if their time is shared better?