Backup Power Calculator for a Condominium Association (OSBB)
Enter the total power of the critical loads and the required backup duration. The result is a guide for discussion, not a power supply design.
Your result
Fill in the form and press 'Calculate'.
Calculation example
Input data: Total power of critical loads: 3000 W; Required backup duration: 4 h; Connection: Single-phase; Simultaneity factor: 100 %.
| Indicator | Value |
|---|---|
| Continuous inverter power, at least | 3 000 W |
| Running apparent power, at least | 3 750 VA |
| Peak power with safety factor | 4 688 VA |
| Phases | single-phase |
| Indicator | Low | Target | High |
|---|---|---|---|
| Usable energy, kWh | 11,59 | 15,65 | 21,13 |
| Nominal battery capacity, kWh | 20,13 | 27,17 | 36,68 |
The result is indicative and is not a power supply design or a promise of backup duration.
Missing data:
- Power factor (cos φ): Aggregate load
- Insufficient data: an engineering calculation is required.
Calculation module version: 1.0.0.
How it is calculated
- Energy over the period = power × hours × duty factor.
- Usable energy = energy × (1 + reserve) / inverter efficiency.
- Nominal battery capacity = usable energy / allowed depth of discharge / (1 − temperature loss) / (1 − ageing reserve).
- Peak apparent power = (running apparent power − apparent power of the starting load + its starting power) × safety factor.
Assumptions (unconfirmed, replace with equipment data)
- A reserve of 20%, inverter efficiency of 0.92, depth of discharge of 0.8, temperature loss of 10%, ageing reserve of 20% and a starting safety factor of 1.25 are unconfirmed assumptions and must be replaced with data for the specific equipment.
- If cos φ is not given, 0.8 is used to convert W to VA; this is recorded as missing data.
Limitations
- The calculation does not account for several motors starting at once, harmonics, voltage drop, partial discharge on a schedule, or load changes during the day.
- Elevators, pumps and other electric motors require an engineering calculation.
- Installation, connection and selection of protective devices must be carried out only by qualified specialists.
Frequently asked questions
Is the result a power supply design?
No. It is an indicative estimate based on the data you entered. The design is prepared by a qualified designer.
Why does the result show a range?
The input data and assumptions are uncertain, so a low, target and high estimate are shown.
Can an elevator be backed up?
It depends on the drive type, the starting scheme and the manufacturer requirements; it is impossible to answer without an engineering survey.
Would you like to be contacted? (optional)
Leave your contact only if you agree. Data is not passed to SunEco or other suppliers automatically.