How to Build Your Own Small-Scale Hydroelectric Generator

Building your own small-scale hydroelectric generator can be a fun and rewarding project. With some basic materials and tools, and a good understanding of the principles involved, you can harness the power of flowing water to produce clean, renewable electricity for your home or cabin.

What is a Small-Scale Hydroelectric Generator?

A small-scale hydroelectric generator uses the energy of flowing water to spin a turbine connected to a generator to produce electricity. The amount of power produced depends on the volume and speed of the water flow.

Small-scale systems are defined as producing up to 100 kilowatts of power. They are suitable for providing electricity to remote homes, cabins, or small communities. The key components are:

Siting Your Hydro System

Finding the right location to build your hydroelectric generator is key. Look for a site with:

Ideally the site will allow you to:

Water Flow Measurements

To size your system right, you’ll need to measure the water flow available at your site:

Intake Design

The intake structure diverts water from the stream into your hydro system. Key factors in intake design include:

Penstocks and Piping

Penstocks are pipes that deliver water from the intake to your hydro turbine. The most common materials used are PVC plastic, HDPE plastic, steel, and concrete:

Key factors for penstock design:

Choosing a Turbine

There are two main types of hydro turbines suitable for home systems:

Impulse Turbines

Impulse turbines are driven by water jetted from a nozzle directed at the turbine's buckets or blades. Advantages:

The main impulse turbine choices are:

Reaction Turbines

Reaction turbines sit directly in flowing water driven by the reaction force as they redirect the water past their blades. Advantages:

The main reaction turbine options are:


The turbine shaft spins an internal rotor inside the generator to produce AC electricity. Key generator factors include:

Batteries and Inverters

Most home hydro systems use batteries to store energy and inverters to convert the generator's DC current to standard 120/240-volt AC current for home use.


If designing your own system from scratch seems daunting, there are kits with all components like this available to simplify construction while still allowing custom configuration:

{{< img src="" title="Example small scale hydroelectric generator system components kit" alt="photo of a kit containing pipes, turbine, battery box, and other parts" width="400px" >}}

For a custom build, follow these general steps:

  1. Construct water intake system and connect to penstock piping.
  2. Install turbine and generator equipment inside protective housing.
  3. Set up storage batteries, inverter, and electrical system.
  4. Integrate monitoring and control systems.
  5. Connect water source to turbine then turbine to electrical load.
  6. Test system operation and efficiency. Troubleshoot any issues.
  7. Perform final optimizations for long-term operation.

Permitting and Regulations

In most locales, some form of permitting or registration is required for diversion of water flows. Research your local regulations and contact agencies early in the planning process. Key permits may include:

In Conclusion

Building a small scale hydroelectric generator takes research, careful planning, and a fair bit of effort to implement correctly. But with a good reliable water source and the right components selected, you can be producing your own clean, renewable electricity for minimal operating cost for years to come.