Expanding your facility: can your grid connection keep up?
New equipment may fit inside a factory while still requiring changes to its electrical installation and grid connection. A facility adding two EV chargers illustrates how to assess power requirements, operating schedules and expansion plans before ordering equipment.
Energy consumption and power requirements are different
Energy, measured in kWh, tells you how much electricity is consumed over a period. Power, measured in kW, describes demand at a given moment. A business may have moderate annual consumption but a high peak when several devices operate simultaneously.
Check approved connection capacity, measured peak demand and the installation's technical capability before expansion. Interval data helps establish the load profile, but brief starting events may require additional measurements and engineering calculations. Unused approved capacity alone does not confirm that new equipment can be connected safely.
Why is adding rated power not enough?
An equipment list is a useful starting point, but devices do not always operate simultaneously or at full power. Some equipment also draws additional current briefly at start-up. A designer must assess operating patterns and equipment characteristics.
A facility reaches 180 kW and two planned chargers could add a combined 44 kW. If both demands coincide, the initial total is 224 kW.
This is a starting point for analysis, not a design calculation. Other loads, operating patterns and installation capacity still need checking.
Which options should you compare?
Scheduling equipment or managing charging power may sometimes limit peaks. Other cases require installation upgrades and increased grid-connection capacity. The choice depends on which loads can be deferred and how critical reliable supply is to the process.
Solar output varies with weather and time of day, so it cannot simply be subtracted from maximum power requirements. A battery helps only within its power, available energy and control limits. Assess both against the actual operating profile.
When should you involve the network operator?
If the analysis indicates a capacity increase, consult the responsible operator early. HEP ODS describes the procedure for obtaining connection approval for an increase in connection capacity in Croatia. Documentation and steps depend on the proposed works.
HEP ODS guidance on increasing connection capacity (Croatian)
What should you prepare for the technical discussion?
- Existing grid-connection approval and electrical-installation documentation.
- Available consumption and peak-demand measurements.
- New equipment specifications and intended operating patterns.
- Further expansion plans, deadlines and acceptable downtime.
An early check allows equipment selection, electrical works and the operator's process to be planned together. The expansion decision can then include the infrastructure required for reliable operation.
How does managed charging change the picture?
Continue the example with an assumed approved capacity of 200 kW and an existing facility load of 180 kW. Two 22 kW chargers at full simultaneous output bring the initial total to 224 kW, or 24 kW above the assumed approved capacity.
The arithmetic difference is 20 kW. A control system could limit total charging power according to measured site demand. However, 20 kW is not automatically the correct design setting: the installation, load distribution, system response and suitable margins require assessment.
Delivering a total of 80 kWh to two vehicles at a constant 20 kW takes an ideal 80 ÷ 20 = 4 hours. At 44 kW, it would take about 1.8 hours, but that power is not available alongside the facility load in this scenario.
Actual duration depends on the vehicles, losses and changing available power. The business question is whether vehicles can remain connected long enough.
Four checks before procurement
- Approved capacity and grid conditions. Check the connection approval and conditions applying to the site.
- Existing installation. A qualified designer should assess relevant cables, distribution equipment, protection and other components. Contracted capacity alone does not prove suitability for the new use.
- Actual operating patterns. Identify overlapping loads, activities that can move to another time and processes that must not stop.
- Future expansion. Include known later phases when assessing staged upgrades.
How can you compare possible solutions?
| Option | Worth considering when | Main limitation |
|---|---|---|
| Load scheduling | Some processes can run at different times | Production schedules and deadlines |
| Managed charging | Vehicles remain connected long enough | Energy required before departure |
| Battery storage | Short peaks have a defined coverage requirement | Power, available energy, recharging and cost |
| Higher connection capacity | A sustained increase cannot practically be rescheduled | Operator conditions, works, timelines and costs |
These options can be combined. Consider operational availability and total cost, as well as equipment purchase price. Include solar in the site-profile analysis, but do not treat its output as constantly available power.
Technical value and financial value are different
Limiting peaks may have technical value even without a separate peak-demand charge. Financial benefits depend on the tariff model. HEP ODS lists peak active-power charges for certain models; other models do not include this as a separate component. Check your tariff structure (Croatian).
Your first step: before ordering equipment, list planned loads, required power, operating hours and deadlines. Ask the technical assessment to state what the existing site can accommodate, which works are necessary and what must be confirmed with the operator.
Procedure source: HEP ODS, linked above. The technical scenario is illustrative and does not replace an engineering design calculation. References to connection procedures and tariffs relate to Croatia. Content reviewed on 15 September 2026.