Micro-Hydro Power Calculator

Enter your site's head (vertical drop), flow rate, and pipe length to calculate the estimated power output of your micro-hydro system. You'll get results for gross power, net power after friction losses, and estimated annual energy value — everything you need to assess your small-scale hydroelectric potential.

ft

Vertical distance the water falls from intake to turbine. Measured in feet.

Volume of water passing through the turbine per unit time.

Length of the penstock pipe from intake to turbine. Used to estimate friction losses.

%

Typical micro-hydro systems operate at 50–70% efficiency. Use 60% if unsure.

$/kWh

Your local electricity rate per kWh. US average is ~$0.13.

Results

Net Power Output

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Gross Power (Before Losses)

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Annual Energy Generation

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Estimated Annual Energy Value

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Estimated Friction Loss

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Net Head Used

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Flow Rate Used

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Power Breakdown (Gross vs Losses vs Net Output)

Frequently Asked Questions

What is 'head' in a micro-hydro system?

Head refers to the vertical distance (pressure difference) between the water intake and the turbine. It's typically measured in feet or meters. A higher head means more potential energy available per unit of water flow, which directly increases power output.

What flow rate do I need for a viable micro-hydro system?

Even small streams can power a micro-hydro system if combined with sufficient head. As a rough guide, a system with 30 feet of head and 50 GPM of flow can generate several hundred watts. Your exact needs depend on your electricity demand and site conditions.

What efficiency should I use for my calculation?

Most micro-hydro turbines operate at 50–70% overall system efficiency, accounting for turbine, generator, and penstock friction losses. If you're unsure, 60% is a commonly used planning estimate and is the default in this calculator.

What is the difference between gross power and net power?

Gross power is the theoretical maximum energy available from the water before any losses. Net power is what you actually get after accounting for pipe friction losses and turbine/generator efficiency. Net power is the figure you should use for planning your system.

How do friction losses in the penstock affect output?

Friction in the penstock (supply pipe) reduces the effective head at the turbine. Longer pipes and smaller pipe diameters increase friction losses. This calculator estimates friction loss as a function of pipe length relative to head, giving you a conservative net power figure.

Can I use a micro-hydro system if I have low head but high flow?

Yes — low-head, high-flow sites can still generate useful power, but they typically require different turbine types such as Kaplan or crossflow turbines. The power formula accounts for both head and flow, so enter your specific values to see what's feasible.

How is the annual energy value calculated?

Annual energy (kWh) is calculated by multiplying net power (kW) by 8,760 hours per year, assuming continuous water availability. This is then multiplied by your local electricity rate to estimate the annual financial value of the energy generated.

Is it feasible to use a turbine powered by a pump-driven water system?

Almost always no. Installing a turbine in a system powered by an electric pump causes the pump to work harder, consuming far more electricity than the turbine could ever generate. Micro-hydro systems are only cost-effective when using naturally flowing or gravity-fed water sources.

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