Community ProjectsEnergy SystemsUrban ProjectsVillage DevelopmentWater Harvesting

Micro-Hydro for a Slovak Village

A turbine with a 21 kWh generating capacity is the centrepiece of
a little village in the mountainous north central region of Slovakia

The village of Necpaly sits at 510 metres above sea level, on the eastern edge of the Necpalská Valley, in the Turiec region in the mountainous north of landlocked Slovakia. The area is filled with rolling hills and cascading valleys framed by mountain ranges peppered with deer, wild pig and bear. And, noteworthy for this particular article, the area boasts abundant flows of crystal clear water.

The village itself is ancient. Earliest written records/documents from Necpaly date back to the year 1266, but archeological evidence of habitation go back as far as the bronze age. I would describe the climate as cold temperate. The average annual temperature is 7.5°C and rainfall is around 830mm per year. Temperatures can reach as high as 42°C (108°F) in summer and as low as -25°C (-13°F) in winter. (As the climate warms the former, high temperatures are becoming increasingly common, and the latter lows almost not known any more.)

Entering the village of Necpaly

The other side of the turbine

I recently had opportunity to visit Necpaly to check out a micro hydro system that has been running there for three years now. The village has a population of around 850 people, with, I would guess, a little less than 200 houses. The turbine pictured at top has minimum/maximum generating capacities of 16 to 21 kWh, depending on seasonal water flow changes. This is enough power for more than twenty five houses, although its actual usage is a little more complicated, since instead of just feeding private residences the electricity powers street lights as well as the main community infrastructure buildings like the village hall, school, etc.

The micro hydro installation consists of a three hundred metre long diversion from the village stream, with the turbine situated part way along this man made channel. The diversion enables an artificially generated height advantage for increased head pressure, and runs for two hundred metres to create a four metre drop where the turbine sits, and then runs for another one hundred metres before it meets back up with the originating stream.

The intake for the diversion also has a few overflow spillway points to ensure the turbine doesn’t attract more water than it can handle. Excess water simply drops back down to the originating stream.

Part of the three hundred metre stream diversion

Where the diversion returns to its source there is an additional three metre drop where another, smaller, turbine could be installed. There is, in fact, a plan for two more smaller turbines to add to the success of the original.

The whole system is quite aesthetically laid out – with parts of it forming attractive water features for the village.

Most people looking at the turbine would intuitively assume the water powers the turbine from above. Instead, the turbine spins in an anticlockwise direction (if you’re facing it as per picture below).

The water drops four metres and is focussed through a smallish opening at
bottom of the boxed construction, forcing the water to rush upwards and fuel
the turbine from below

The installation cost €100,000 (US$140,000). Given its generating capacity alone, the system should pay for itself within ten years at the outside. But, it gets a little more attractive again in this instance, as excess generating capacity is sold back to electricity companies, in accordance with EU laws that require these companies to purchase excess renewable power. This is called a Feed-In Tariff, a mechanism that has had a lot of success in ramping up the uptake in renewables in Europe – Germany in particular, being the first European country to begin serious implementation of the system. This factor should decrease total payback time quite significantly.

The installation was financed by an EU subsidy as well as local shareholder investment in the project. Investors get a return by way of the above-mentioned sell-back of excess power as well as sale of base power to the villagers themselves.

Once established, maintenance for the system is low. Beyond the hardware connected to the turbine itself, winter and spring months bring leaves that need to be filtered out of the system, and the diversion itself can require a little patching to reduce leakage.

Some maintenance in spring is essential – clearing autumn leaves and branches
that wash down the valley into the system. This metal grid filters the leaves
and creates a collection point for them

Water can leak through the diversion channel

Mankind has harnessed water energy to power village life and labours for thousands of years, and there is no reason why this cannot still be the case for a great many places worldwide. A little further intelligent design of such systems could see other synergies incorporated. At the moment, for example, Necpaly villagers are toying with the idea of farming fish in the diversion channel, and another potential improvement could be to see overflows running into swales to subsequently and passively irrigate gardens, etc.

Tell us your micro-hydro tales!: I’d love to hear your micro-hydro stories. Not only for largish-turbine systems such as this, but also smaller power generating systems that might supply small house clusters, single houses, or even just aspects of a single house. Reading about these systems on the net is one thing, but getting practical insights and endorsement from people who’ve installed and/or tinkered with and tailored such systems speaks volumes more. Let us know either by comments below, or send a few pics and a short article to me on editor (at) for posting on this blog.

A Honey Buzzard patrols Necpaly – keeping the mouse population in check


  1. It would be helpful if information could be provided as to the where a bouts of vendors or suppliers of systems such as this could be included in the article.

  2. A few months ago i called an engineer of the german company Hydrowatt in Karlsruhe (southwestern Germany, near Strasburg). I wanted to know how it would be possible to resurrect thousands of old water power places which once were active in the beginning of the 20th century (about 60.000 – 80.000) in order to get more alternative power. Today there are only about 1000 – 2000 active.
    One big argument against is always that this constructions would harm fishs.
    But there are already a lot examples that these constuctions can even enhance the situation of the fishes.
    In the past there were no possibilities for fishes (i believe that, i don’t know it) to get around watermills. Today there are so called fish staircases. The water volume before the watermill (usually tens of cubicmeters) is a safe place for fishes in summer, when water is scarce.

    The engineer told me that for a 5kW you have to calculate about 50.000 Euros for the turbine, the generator, the control system etc. Another 50.000 Euros you need to built the sluice valve, the rake, walls etc.

    Here is the link for the company (specialised on small turbines):

    Some pictures of waterwheels:

  3. Well done with highlighting what other communities have been doing to supply their energy needs and protect the emnvironment. Ireland has so many streams and rivers that could be harnessed. The Archimedas Screw is used very effectively to both harness the power from falling water and still allow the fish to travel upstream and downstream.

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