Repsol YPF

These systems charge batteries through different energy sources: solar, wind, hydraulic, through a generator or using the electricity grid. The batteries can run using numerous resources, from renewable energy to biofuels, or natural gas, propane, butane and many more besides. Furthermore, integrating these modules with the other components optimises stand-alone energy generation systems in real conditions. 

They are used to produce heat, generate cold, manage data… In reality, these stand-alone systems can be adapted to any place but, above all, they guarantee energy in isolated places, such as farms. They feed off one or more combinations of energy sources. Their designs often implement technologies based on diesel or gas cogenerators. 

Technical description 

These systems are usually hybrid. Then can use mini-plants (wind, hydraulic, photovoltaic, etc.) which supply them with uninterrupted energy. They combine, depending on the type, the force produced by the turbines which move renewable energy sources, with that of a diesel or other generator, always processed by mechanisms which operate continually. 

For example, the energy produced by a diesel engine is used to produce heat for heating and hot water, to light up a room or to air condition it. A typical installation can be composed of a cogeneration group, a converter, an inverser, various electronic systems and the necessary accumulators. Nowadays, the latter, thanks to technical progress, do not require maintenance. 

A mechanism, called a measuring transductor, informs the central control unit of electricity, heat and mechanical parameters so that it can act on them, either directly or by activating the control servosystems. That way, the diesel generator is switched on or turns off so that it only produces the energy required, which may be the difference between that coming from the engine and that produced at the time by a windmill, solar panels or another renewable energy source. 

In other words, if consumption reduces or stops, the generator stops and the accumulators continue to provide the supply. A regulator maintains the accumulators with the appropriate load, prolonging its useful life by protecting it from overloads and underloads. The parameters and the servocontrol function are recorded and the data can be viewed.

Selection criteria

It is about obtaining the maximum output and the greatest energy efficiency, as well as prolonging the useful life of the entire system as much as possible. Although it seems complex, all of the abovementioned elements use sufficiently established technologies, are reliable and are available on the market. 

Meanwhile, the electricity installation of somewhere powered by a stand-alone energy generation system needs two lines: one triphase, connected to the production machinery, and another monophase, allocated to lighting, domestic appliances and other appliances that need uninterrupted power, such as computers, the video, the television, etc.

The technology for this type of system is usually modular, expandable and adaptable depending on the consumer’s needs. In order to design these systems, the professionals weigh up criteria concerning energy sources and their capacity. The analysis they consider includes studies on existing renewable energy sources at the site. Solar radiation atlases and windspeed and distribution measures, as well as an estimate of the property or warehouse’s consumption, are key when deciding which energy sources will power each stand-alone system. Consumption depends on the number of appliances and light fittings that must be powered and how long they are used for each day.

Saving energy is very important where stand-alone systems are concerned, since this lowers the maintenance cost and investment. Nevertheless, the incorporation of several energy sources makes the use of renewable energy sources profitable. As such, mixed stand-alone systems are considered to be environmentally-friendly. 

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