Types of Microhydro Systems

Types of Microhydro-Electric Systems

As with wind- and solar-electric systems, hydro-electric systems can be divided into four configurations:

• On-grid without batteries. This a simple and efficient system that sends any surplus energy back into the grid to be credited to you for use at other times. These systems typically do not provide backup for utility outages.
• On-grid with batteries. This system type also sells back surplus electricity, but also provides backup during utility outages. The amount of backup will be determined by the system’s capacity and the battery size.
• Off-grid without batteries. This configuration is generally for larger, AC-generating systems. The peak load capacity (how many things you can operate at once) is determined by the hydro system’s peak generating capacity. This configuration is generally not used for systems that generate at less than about 2 kW.
• Off-grid with batteries. This is the most common off-grid option, and is similar to off-grid solar- or wind-electric systems. The charging source puts energy into a battery bank, while loads are run from the batteries—directly, if DC; via an inverter, if AC.

Microhydro-electric systems can power most, if not all, electrical loads, depending on the size of the resource. The smallest systems may only provide for lighting, electronics, and basic refrigeration. But with sufficient head and flow, these systems can run heating and cooling systems, tools, and even commercial equipment in a modern, on-grid home, ranch, or business. The head and flow are the limitation, and it all comes down to how much power (wattage) and energy (kilowatt-hours) you have at your disposal.

While people with solar-electric and small wind-electric systems may be pushed toward serious efficiency and conservation measures because of the cost of these renewable kilowatt-hours, small hydro systems frequently have ample resources behind them, and can be more generous with their output. However, using your energy wisely can mean using less water and smaller equipment, which means lower environmental impact and lower cost.