Health facilities have a number of technology options available to supply reliable electricity, including Photovoltaic (PV), Wind, Reciprocating Engines (generators), Hybrid Systems, and Grid Extension.

Ideally, health facilities would receive low cost reliable power from the grid. Unfortunately, this is rarely the case and health facilities must rely on a variety of on-site technologies to provide reliable, high quality power. Technologies typically involve some combination of energy generation, storage, and power conditioning capabilities.

Below is a short summary of some common energy generation and storage technologies. In general, renewable energy options will have higher capital costs than diesel or other fuel based electricity generating options. However, over the long term, renewable systems often have lower operating costs and produce fewer or no emissions. Hybrid systems are an excellent choice for many off-grid health facilities.

Refer to this table for an illustration of key characteristics of energy generation technologies, and an illustration of the estimated cost of various energy technologies for a range of clinic sizes. Refer to the health facility load calculation and system optimization tool for a comparison of the lifecycle cost of different technology configurations.

Batteries and Battery Management

Batteries are a critical component of almost all energy systems which involve an intermittent power generation source – including a diesel generator, solar PV system, wind, or intermittent grid. Batteries provide a means to store energy which can be used to power the health facility when the intermittent power supply source is not operational (e.g. when the sun is not shining, the wind is not blowing, or the grid power is off). Batteries have proven to be one of the most challenging components of an energy system to keep operational.

Electrical distribution poles carrying power lines to a home.

Grid Extension

Grid Extensions connects the facility to the local utility grid. If available, grid power is typically the most cost effective power supply, although the cost of extending lines to rural facilities can be prohibitively expensive. The quality of grid power in developing countries is often poor, so on-site technologies are often required regardless of whether a facility is connected to the grid or not.

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Hybrid Systems

Hybrid Systems employ a number of different technologies. A system could include photovoltaic panels, a wind turbine, batteries, and a generator. With reliable solar and wind resources, this system would rarely need to rely on a generator. Since the generator can recharge the batteries during prolonged periods of inclement weather, the battery bank in a hybrid system can be significantly smaller than a PV-battery system, perhaps only needing to store one or two days' worth of energy. Diesel/PV/battery or Diesel/battery hybrid systems should be seriously considered for all but the smallest of off-grid health facilities.

Inverters

Inverters convert DC to AC power. This capability is needed because batteries produce DC power while most common electrical applications and devices require AC power. DC-only systems are appropriate for health facilities with limited loads such as lighting, communication, and refrigeration.

Photovoltaic (PV) Systems

Photovoltaic (PV) Systems generate electricity from sunlight collected by solar panels. Energy collected in this manner can be used to supply direct power to electrical equipment, or it can be stored in batteries to provide indirect power.

Reciprocating Engines (Generators)

Reciprocating Engines (small generators) are the most common form of small generator. In generator-only systems, the generator must be sized to handle the peak expected load, but the system frequently runs at lower loads at reduced efficiency. It is common to find oversized generators at many development country health facilities. Running an oversized generator is expensive and inefficient and should be avoided.

Wind Turbines

Wind Turbines generate emissions-free electricity from a renewable energy resource. Situating a wind turbine on a site requires careful measurement of wind patterns. While extensive maps of solar resources exist, the same is not true of wind resources. Small wind turbines are available with capacities in the range of a few hundred watts. Larger turbines offer significant economies of scale. Similar to PV systems, wind turbines must be connected to the grid or to a battery system to provide continuous power.

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Last updated: September 28, 2011

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