Measure the shortfall
Add the existing coincident demand to the additional load that will operate at the same time. Subtract the modelled import limit. The positive difference is the power support required. For example, 240 kW of existing demand plus a 150 kW additional load against a 300 kW limit creates a 90 kW shortfall. The headroom calculator treats these as user-entered assumptions, not verified site readings.
Power and duration must both work
A 90 kW shortfall lasting two hours requires 180 kWh of delivered energy. A battery with enough stored energy can still fail this test if its inverter cannot deliver 90 kW continuously. Conversely, a high-power battery may run out of energy before the peak ends. Deduct any reserve that must remain available for backup or other duties.
Think about the next event
Supporting one peak is only part of the story. The battery needs enough time and import capacity to recharge before the next event. Closely spaced peaks can leave less energy available than the first-event calculation assumes. Temperature derating, maintenance, outages and degradation can reduce support. Our tool assumes the entered usable output is available at the start of one event and does not simulate a whole time series.
Understand what a kW model cannot prove
Some connection limits are expressed in kVA or amperes, and power factor or phase imbalance may matter. Our calculator uses active power in kW and assumes a common measurement point. It does not calculate voltage, fault level, harmonics, protection coordination or compliance. Do not treat a green model result as confirmation that network reinforcement is unnecessary.
Move from screening to engineering
For a real project, give your installer interval data, the agreed connection parameters, the new-load schedule and the proposed battery specification. Ask for a robust control strategy and a DNO-agreed arrangement where needed. An energy management system can coordinate assets, but its commercial and technical duties must be designed for the complete installation.
Sources & further reading
Use current documents and confirm the requirements with your own network operator.
Created by Arcgrid. Educational information for commercial sites in Great Britain, not an engineering design or a guarantee of savings. Scenarios are illustrative. Northern Ireland has different connection arrangements.
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