An overshot water mill is characterized by a higher head and a smaller flow rate. Between 2 and 7 kW of electricity can be generated. The efficiency is good espacially at high heads
At the watermill in Geijsteren an old undershot wheel has been replaced by a Sagbien water wheel. A wheel with superior efficiency and graceful beauty.
An undershot (or breasthot) waterwheel is used with a smaller head and a larger flow rate. The power is often high (5-15 kW). The efficiency is average, but due to the large amount of water this is often not an issue.
Many water mills are not in use anymore, but have not fallen into disrepair yet. In those cases can add a generator. This is always custom work. As a result, an excellent return on investment can be obtained.
A water mill must perform at its maximum in order to generate as much electricity as possible. An automatic control with a PLC is then the right solution.
More and more mill owners want to get zero on the meter or be independent of the grid. Then energy storage is a solution. Gratia Hydro uses Victron's ESS system for this.