Inputs
Tip: change units to match field data.Example data table
Use these scenarios to sanity-check outputs during early planning.
| Scenario | Flow | Gross head | Losses | Overall efficiency | Estimated capacity |
|---|---|---|---|---|---|
| Run-of-river | 3.5 m³/s | 22 m | 5% | 0.83 | ≈ 627 kW |
| Canal drop | 1,200 L/s | 12 m | 1.0 m | 0.80 | ≈ 904 kW |
| High head | 45 cfs | 180 ft | 8% | 0.88 | ≈ 1,636 kW |
Formula used
The calculator estimates theoretical hydropower and then applies combined efficiency:
- ρ = water density (kg/m³)
- g = gravity (m/s²)
- Q = flow rate (m³/s)
- Hnet = gross head − head losses (m)
- η = turbine efficiency × generator efficiency × (1 − auxiliary losses)
Power is reported in kW and MW. Energy is estimated as: Energy = Power × Hours × Capacity Factor.
How to use this calculator
- Enter flow rate from gauging or design discharge.
- Enter gross head from survey levels or drawings.
- Select a head-loss method and provide losses.
- Set efficiencies using vendor data or typical ranges.
- Choose capacity factor and hours for energy estimation.
- Press Calculate to view results above the form.
- Use CSV or PDF export for reports and submittals.
Professional guide to hydropower capacity planning
Hydropower capacity is driven by three measurable site conditions: available flow, usable head, and the system’s ability to convert hydraulic energy into electrical output. In construction planning, a reliable capacity estimate helps you size civil works, select turbine-generator packages, and confirm that electrical infrastructure (switchgear, transformers, and transmission) matches the expected load. This calculator follows standard practice by converting your inputs into consistent units, subtracting head losses to obtain net head, and applying combined efficiencies to estimate realistic capacity rather than ideal hydraulic power.
Start with the best flow value you have: a gauged discharge, a design flow from hydrology, or a conservative percentage of seasonal availability. Next, confirm gross head from survey levels or drawings. Losses represent energy dissipated through intake screens, penstock friction, bends, valves, and the draft tube. Early feasibility can use a percent loss (often 3–10%), while design should move to calculated losses from pipe roughness, length, diameter, and fittings. Efficiency is equally important: turbines have peak efficiency at certain operating points, generators vary by rating, and auxiliary losses capture station service, controls, and transformer effects.
The result section reports total capacity and per-unit capacity to support equipment selection and redundancy planning. The energy estimate uses capacity factor and operating hours to approximate annual production for budgeting and feasibility. If you have a flow duration curve, choose a capacity factor that reflects the portion of the year your plant can operate near the target flow.
Use the exported CSV and PDF outputs for site reports, option comparisons, and early-stage submittals. Final design should be validated with vendor curves, penstock loss calculations, and measured head and flow under operating conditions.
FAQs
1) What is the difference between gross head and net head?
Gross head is the total elevation drop. Net head subtracts losses from friction, fittings, and intake or draft components. Net head is the value used to compute power.
2) Which flow should I enter for preliminary sizing?
Use a conservative design flow based on hydrology, minimum regulated release, or reliable seasonal discharge. If uncertain, run multiple scenarios to bracket the likely operating range.
3) What head-loss value is reasonable at feasibility stage?
A planning allowance of 3–10% of gross head is common, depending on penstock length, diameter, and appurtenances. Move to calculated friction losses once alignment and pipe sizing are defined.
4) How do turbine and generator efficiencies affect capacity?
Capacity scales directly with combined efficiency. If overall efficiency drops by 5%, power drops by about 5%. Use vendor curves where possible, especially for part‑load operation.
5) What does capacity factor mean in the energy estimate?
Capacity factor reflects how often the plant produces near its rated power over time. It captures seasonal flow variation, outages, and operational constraints, turning capacity into an annual energy estimate.
6) Can I use this for multiple turbines or units?
Yes. Enter the total site flow and head, then set the number of units. The calculator reports total capacity and per‑unit capacity to support equipment rating and redundancy planning.
7) Why do my results differ from a vendor proposal?
Vendors may model turbine curves, guaranteed net head at rated flow, temperature effects, and detailed losses. Use this tool for transparent estimates, then refine inputs using measured data and vendor performance curves.