Frequently Asked Questions of Micro Hydro Power

1. What is micro-hydro power?

Hydropower systems that generate up to 100 kilowatts (kW) of electricity are often called micro-hydro systems. Most of the systems used by home and small business owners would qualify as micro hydro systems. In fact, a 10 kW system generally can provide enough power for a large home, a small resort, or a hobby farm.

2. How does a micro hydro system work?

Micro hydro systems use the energy in flowing water to produce electricity or mechanical energy. A portion of a river or stream’s water is diverted to a channel, pipeline, or pressurized pipeline (penstock) that delivers it to a waterwheel or turbine. The moving water rotates the wheel or turbine, which spins a shaft. The motion of the shaft can be used for mechanical processes, such as pumping water, or it can be used to power an electric generator.

The basic principle of hydropower is that if water can be piped from a certain level to a lower level, then the resulting water pressure can be used to do work. If the water pressure is allowed to move a mechanical component then that movement involves the conversion of the potential energy of the water into mechanical energy. Hydro turbines convert water pressure into mechanical shaft power, which can be used to drive an electricity generator, a grinding mill or some other useful device.

3. What are the system components?

Small hydro power systems consist of these basic components: Water conveyance-A channel, pipeline, or pressurized pipeline (penstock) that delivers the water; a turbine or waterwheel, which transforms the energy of flowing water into rotational energy; an alternator or generator, which transforms the rotational energy into electricity; a regulator, which controls the generator, and wiring, which delivers the electricity.

4. What are the advantages of using a hydro system?

Although there are costs in buying and installing the system, a hydro power system will typically last a long time and maintenance is usually not expensive. In addition, there are a variety of financial incentives available on the state, utility, and federal level for investments in renewable energy systems. They include income tax credits, property tax exemptions, state sales tax exemption, loan programs, and special grant programs.

5. Is micro hydro practical for you?

To build a small hydropower system, you need access to reliable flowing water. A sufficient quantity of falling water must be available, which usually, but not always, means that hilly or mountainous sites are best. There are specific methods for calculating whether the water flow you have is sufficient to power a turbine.

6. How do I know if I have a good microhydro site?

If you have enough head and flow and have designed the catchment, distribution and generating system so that it can’t freeze (or to prevent its operation in freezing weather) and have connected the generator to a suitable energy storage system, then you should have the covered the basics for a useful micro hydro installation.

Quantitative measurement of both head and flow must be done in order to know how much energy your hydro site is capable of producing. Also, since there will be considerable seasonal variation in the flow rate of area streams, it is important to know how the flow rate will vary over time. Month-to-month and even year-to-year variability needs to be estimated in order to make even a rough approximation of total energy output from a hydro source.

In the end, it is usually some combination of actual measurement and estimations that yields a final number. Indeed, uncertainty in micro hydro potential often discourages its consideration as a feasible renewable energy option. On the other hand, equipment costs can be the lowest among renewable options, which may offset this uncertainty factor.

As with other renewable energy options, a site evaluation is recommended to assess the feasibility and the costs.

7. Is it legally feasible?

Most water is regulated by government, in some form or other. Before constructing anything you should consult with local and regional government offices regarding permits and restrictions.

8. How much does it cost?

On a per watt basis, micro hydro generators are not as expensive as photovoltaics or wind turbines. Combine this with the fact that hydro is often a constant-output, 24/7 resource, and you have a compelling argument to invest if you have the resource available to begin with.

Total costs including labor for a small off-grid micro hydro system (with inverter, batteries, load panel and code-compliant safety equipment) may run between $10K and $30K, where labor is the largest variable.

For remote locations, the outlay to acquire grid interconnection will likely make a robust micro hydro site very appealing. For a home or business already connected to the grid, micro hydro may also be advisable, depending on the power available at the site.

As with the other renewable energy options, a Site Evaluation is necessary to assess the feasibility and the costs.

9. Can I sell my power?

You can usually sell any excess power to your local utility. If you decide to sell, you’ll need to contact the utility to find out application procedures, metering and rates, and the equipment the utility requires to connect your system to the electricity grid. (It’s generally best to do this before you purchase your hydro system.)

10. What’s the environmental impact?

Hydropower is a very clean source of energy. It is one of the most environmentally benign energy conversion options available, because unlike large-scale hydro power, it does not attempt to interfere significantly with river flows. After use, the water is available for other purposes (although on a lower horizontal level). And unlike traditional power stations that use fossil fuels, micro-hydro generators have practically no impact on the environment. In fact, by reducing the need to cut down trees for firewood and increasing farming efficiency, micro-hydro has a positive effect on the local environment.


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