Plan backup capacity for critical site operations. Tune depth of discharge, voltage, and safety margin. Get clear sizing, then export it to your team.
Size battery storage for jobsite daily energy needs. Account for surge loads, autonomy, losses, and reserve. Download CSV or PDF results for faster crew planning.
| Scenario | Critical kW | Peak kW | Hours | Days | Voltage | Nominal kWh | Capacity Ah | Modules (5.12 kWh) |
|---|---|---|---|---|---|---|---|---|
| Concrete pour night shift | 5 | 8 | 10 | 1 | 48 | 106.10 | 2210 | 21 |
| Crane standby and lighting | 3 | 5 | 12 | 2 | 48 | 152.78 | 3183 | 30 |
1) AC energy required
EAC (kWh) = Critical kW × Backup hours × Autonomy days
2) Loss-adjusted energy at the battery
EDC = EAC ÷ (Inverter eff × Battery eff)
3) Usable storage required (temperature adjusted)
Eusable = EDC ÷ Temperature availability
4) Nameplate storage to install
Enom = Eusable ÷ DoD × (1+Reserve) × (1+Future)
5) Approximate capacity in amp-hours
Ah = (Enom × 1000) ÷ DC voltage
This sizing is energy-based. Check current limits, cable sizing, and allowable C-rate for your selected battery modules.
Battery sizing starts with a realistic load profile. Separate critical loads such as lighting, pumps, controls, communications, and safety systems from optional tools. Use nameplate power only as a check; measure typical kW with meters or equipment logs. If loads cycle, estimate duty factor and average kW over the backup window. A clean profile reduces oversizing and avoids unexpected brownouts.
Runtime is the second driver. Multiply average critical kW by backup hours and the number of outage days you want to cover. For construction, autonomy often depends on delivery schedules, fuel restrictions, and local grid reliability. Short, frequent outages may favor fewer hours with higher surge capability. Long outages push energy capacity higher and may require staged load shedding to keep essentials running.
Stored energy is not fully delivered to AC loads. Inverter conversion, battery round‑trip losses, and cabling reduce usable energy. Temperature also matters; cold mornings and hot enclosures can lower available capacity. The calculator converts AC energy to DC energy using efficiencies, then derates with a temperature availability factor. Conservative values protect performance when conditions are worse than planned.
Reserve margin is practical insurance. It covers forecast error, seasonal temperature changes, and battery aging that reduces capacity over time. Future expansion accounts for added trailers, extra lighting towers, or a new pump. These factors are applied as multipliers on the nameplate kWh requirement. For projects with tight deadlines, higher reserve reduces the risk of downtime and costly work stoppages.
After selecting nominal kWh, confirm hardware limits. Verify continuous and surge inverter ratings, battery module current capability, and acceptable C-rate. Check DC bus voltage, breaker sizing, and conductor ampacity for the estimated peak and surge currents. Finally, translate total kWh into module counts for procurement, allowing for spares and maintenance access. Always validate the final design against manufacturer specifications. Document assumptions and review them with the superintendent before ordering.
Critical load, backup hours, and autonomy days drive energy. Peak load and surge factor guide inverter and current sizing. Efficiencies, depth of discharge, and temperature availability convert usable energy into required nameplate capacity.
List essential equipment, note typical watts, and apply duty factors for cycling tools. Use clamp meters or temporary submeters when possible. Convert to kW and average across the backup window.
Using only part of nameplate capacity improves lifespan and keeps a buffer for unexpected demand. The calculator divides usable energy by the planned depth of discharge to obtain installed capacity.
For uncertain loads or harsh weather, use 10–25%. If downtime is expensive, increase it. If you have accurate metering and stable loads, a lower reserve may be acceptable.
It converts total required kWh into an estimated number of battery modules for procurement. Enter your module’s rated kWh and the tool rounds up to the next whole module.
No. It is an energy-based sizing estimate. Confirm breaker ratings, cable ampacity, ventilation, enclosure temperature, and manufacturer limits for continuous current, surge current, and allowable charge and discharge rates.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.