Inputs
Example Data Table
| Scenario | Avg Load (kW) | Peak (kW) | Daily Energy (kWh/day) | PSH | Autonomy (h) | Solar Share | Wind Enabled | PV (kW) | Battery (kWh) | Inverter (kW) |
|---|---|---|---|---|---|---|---|---|---|---|
| Camp buildout | 40 | 120 | 720 | 5.0 | 4 | 70% | No | ~210 | ~420 | ~170 |
| Night-shift works | 55 | 150 | 990 | 4.6 | 6 | 60% | Yes | ~160 | ~770 | ~215 |
| Critical-only backup | 18 | 60 | 0 (auto) | 5.5 | 8 | 40% | No | ~50 | ~340 | ~85 |
Formula Used
Otherwise:
Eday = Pavg × Hop
Ypv = Derate × (1 − Loss)
PV size (kW):
Ppv = (Eday × fsolar) ÷ (PSH × Ypv)
Ewind,kW = 24 × CF
Wind size (kW):
Pwind = (Eday × fwind) ÷ (24 × CF)
Eride = Pcrit × Haut
Nameplate (kWh):
Ebatt = Eride ÷ (DoD × ηrt)
Aging allowance scales nameplate upward.
Pinv = Ppeak × (1+Surge) × (1+Reserve) ÷ ηinv
Generator (optional): peak plus margins and any charging power.
How to Use This Calculator
- Start with your load: enter average and peak demand. If you know daily energy, enter it and leave “Operating Hours” as-is.
- Set reliability targets: choose critical load fraction, autonomy hours, and reserve margin based on outage tolerance.
- Tune renewables: pick solar and wind shares that match your site’s resources and space constraints.
- Check assumptions: derate factors and efficiencies strongly affect results—use conservative values when uncertain.
- Export: after calculating, download CSV for spreadsheets or PDF for a quick design memo.
Load Characterization for Construction Sites
Microgrid sizing begins with measured demand. Construction sites usually have equipment-driven peaks and a smaller overnight base. Record average kW, peak kW, and daily kWh. As a quick check, 40 kW across 18 hours equals 720 kWh/day—typical for a mid-size camp and tools.
Solar Production Assumptions and PV Yield
PV output depends on peak sun hours and a net yield factor. With 5.0 PSH, 0.78 derate, and 5% loss, net yield is 0.741. If PV is set to cover 70% of 720 kWh/day, the target is 504 kWh/day and PV capacity is about 136 kW.
Battery Storage for Ride-Through and Power Support
Storage is sized for energy and power. Energy uses critical load and autonomy, then adjusts for DoD, round-trip efficiency, and aging. A 120 kW peak with 60% critical fraction gives 72 kW critical. At 4 hours, ride-through is 288 kWh; with 80% DoD, 90% efficiency, and 10% aging, nameplate is ~444 kWh.
Inverter, Surge Margin, and Backup Generator Strategy
Inverters must serve peak AC demand plus surge and reserve. For 120 kW peak with 25% surge and 15% reserve, required AC is 172.5 kW; at 96% efficiency, choose ~180 kW. Generators add resilience, cover low-renewable days, and can include extra kW for battery charging.
CAPEX Benchmarking and Scenario Comparison
Use unit costs to compare scenarios and choose a realistic BOS uplift for installation and commissioning. Export CSV to compare options across sites, and PDF to attach to approvals, scopes, and tender packages.
| Example Input Set | Value | Example Output | Result |
|---|---|---|---|
| Avg / Peak Load | 40 kW / 120 kW | Daily Energy | 720 kWh/day |
| Solar Share / PSH | 70% / 5.0 | PV Size | ~136 kW |
| Critical / Autonomy | 60% / 4 h | Battery Nameplate | ~444 kWh |
| Surge / Reserve | 25% / 15% | Inverter Rating | ~180 kW |
FAQs
1) Should I enter daily energy or average load?
Use daily energy when you have metered kWh/day. Otherwise, enter average load and operating hours for an estimated daily energy. Accurate energy input improves PV and wind sizing.
2) What is a good reserve margin for construction microgrids?
Many projects use 10–20% to cover uncertainty, expansion, and equipment derating. Higher margins increase capital cost but reduce the risk of overload and nuisance trips.
3) How do I choose critical load fraction?
Identify loads that must continue during outages, such as safety lighting, IT, dewatering, and accommodation. Express their combined peak as a percentage of total site peak.
4) Why does battery nameplate exceed ride-through energy?
Nameplate capacity is increased to account for depth-of-discharge limits, round-trip losses, and aging. These factors protect battery life and help ensure the autonomy target is still met over time.
5) When should I enable wind sizing?
Enable wind only when you have reasonable site wind data or a defensible capacity factor. Without local measurements, treat wind as a scenario option and keep assumptions conservative.
6) Does the inverter size need to match PV size?
Not necessarily. Inverter rating is driven by peak AC demand plus surge and reserve. PV can be larger or smaller depending on energy targets, curtailment strategy, and battery charging needs.
7) Are these results suitable for final procurement?
Use them for early design and budgeting. Final equipment selection should include detailed load studies, protection coordination, power quality checks, interconnection requirements, and vendor-specific derating and warranty constraints.