Model PV, loads, and battery limits quickly today. See optimal peak shaving and reserve targets. Download reports to share with project teams easily now.
Use this example to validate your inputs and expected outputs.
| Scenario | Battery (kWh) | Initial/Reserve SOC (%) | PV (kW) × Sun (h) | Load (kWh/day) | Peak (kW × h) | Peak Covered (kWh) | PV to Recharge (kWh) |
|---|---|---|---|---|---|---|---|
| Typical site | 20 | 70 / 20 | 6 × 5.5 | 24 | 4 × 4 | ≈ 9.2 | ≈ 9.9 |
| Higher peak demand | 20 | 80 / 25 | 6 × 5.0 | 28 | 6 × 4 | Limited by discharge power | Depends on PV surplus |
| Cloudy day | 15 | 75 / 25 | 5 × 2.5 | 22 | 3.5 × 3 | Often SOC-limited | Often PV-limited |
Example outputs are approximate, because the model simplifies intraday profiles. For exact dispatch, use measured hourly data and inverter controls.
1) Usable battery capacity
Usable_kWh = Battery_kWh × (DoD% ÷ 100)
2) Energy available above reserve
Stored_usable_kWh = Usable_kWh × ((SOC% − Reserve% ) ÷ 100)
3) Split round-trip efficiency
η_rt = RoundTrip% ÷ 100
η_charge = √η_rt and η_discharge = √η_rt
4) Deliverable energy to loads
Deliverable_kWh = Stored_usable_kWh × η_discharge
5) Peak demand energy
PeakNeed_kWh = PeakLoad_kW × PeakHours
6) Peak covered by battery (limited)
PeakCovered_kWh = min(PeakNeed_kWh, Deliverable_kWh, MaxDischarge_kW × PeakHours)
7) PV energy estimate and surplus
PV_kWh = PV_kW × SunHours
AvgLoad_kW = DailyLoad_kWh ÷ 24
LoadDuringPV_kWh = AvgLoad_kW × PVWindowHours
PVSurplus_kWh = max(0, PV_kWh − LoadDuringPV_kWh)
8) PV used to recharge after peak shaving
Battery room is approximated as the energy drawn from storage to cover peak:
StorageDraw_kWh = PeakCovered_kWh ÷ η_discharge
PVNeededForRefill_kWh = StorageDraw_kWh ÷ η_charge
PVToCharge_kWh = min(PVSurplus_kWh, PVNeededForRefill_kWh, MaxCharge_kW × PVWindowHours)
9) Savings estimate
Savings_peak = PeakCovered_kWh × PeakRate
ExportCredit = PVExported_kWh × ExportRate
The calculator is intentionally simplified for early design and planning. If you have hourly data, you can refine the PV window and load assumptions.
Tip: If results look optimistic, reduce sun hours and increase peak load. If results look conservative, raise initial SOC or reduce reserve SOC.
Construction sites often experience variable daytime demand from tools, lifts, lighting, and temporary offices. This calculator converts practical inputs into a daily dispatch plan: how much energy can be delivered from the battery above a reserve, how much peak demand can be covered, and how much solar can refill the battery afterward. It supports early-stage sizing decisions, method statements, and contractor coordination when grid capacity is constrained.
Peak windows typically align with utility tariffs, generator fuel peaks, or site demand spikes. The model estimates peak energy need from peak kilowatts and peak duration, then caps coverage using inverter discharge limits and available state of charge. The output highlights residual peak import so teams can decide whether to adjust schedules, increase reserve, or stage additional storage for critical operations.
Battery health depends on depth of discharge, reserve targets, and efficiency losses. The calculator applies a usable capacity based on depth of discharge and estimates deliverable energy using discharge efficiency. Reserve state of charge is treated as untouchable for reliability, improving outage readiness for safety systems, dewatering pumps, communications, and security loads.
Solar energy is estimated from array size and sun hours, then compared with concurrent site consumption during the PV window. Surplus solar can recharge the battery, limited by charge power and the refill energy required after peak discharge. Any remaining surplus is treated as exported energy, allowing a quick check of potential export credits or curtailment risk.
Because procurement and commissioning require clear documentation, the calculator stores the latest run and generates downloadable CSV and PDF summaries. These reports help align the electrical subcontractor, PV installer, and energy manager on assumptions, limits, and expected savings. For field verification, compare results to metered hourly data and tune inverter control setpoints accordingly. Include weather adjustments, seasonal sun hours, and generator integration when the site evolves.
Dispatch is the planned charging and discharging of the battery across the day. The model prioritizes peak shaving while keeping a reserve for backup, then estimates how much PV can recharge after the peak period.
Round-trip efficiency includes both charge and discharge losses. Splitting it evenly gives a practical approximation for planning energy flow, without needing detailed inverter curves or temperature-dependent efficiency data.
Set reserve based on critical loads, outage risk, and site safety requirements. Higher reserve improves resilience but reduces peak coverage. Use the autonomy section to test reserve levels until supported backup hours match your target.
The PV window assumes average consumption. If loads spike at midday, reduce PV surplus by increasing daily load or shortening the PV window. For accuracy, use metered hourly load profiles and adjust assumptions.
Export rises when PV energy exceeds concurrent load and the battery cannot accept more charging due to power limits or limited refill needs. Increase charge power, expand battery capacity, or add flexible loads to absorb surplus.
Yes, as a planning proxy. Treat generator output as reduced grid import by adjusting load or effective tariff, then compare scenarios. Final settings should be validated with site controls, fuel costs, and emissions constraints.
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.