Off-Grid Photovoltaic System (Isolated)
One of the numerous advantages of solar energy is that it is present all over the place. Off-Grid photovoltaic technology can be used to generate your electricity.
There are two types of photovoltaic systems, according to their connection to the public electricity distribution network:
1 – Isolated Photovoltaic System, also known as Off-grid Photovoltaic System.
2 – Photovoltaic System Connected to the grid, also known as On-Grid Photovoltaic System (in the network).
The concept of an on-grid photovoltaic system and Off-grid photovoltaic system emerged only after the use of the inverter technology to directly connect the photovoltaic solar panels to the grid, without the energy passing through a bank of batteries; which would eliminate one of the most costly (and least durable) components of an isolated photovoltaic system (Off-grid photovoltaic system), which is the battery.
An Off-grid photovoltaic system basically has the following structure:
1 – Photovoltaic Arrangement (the set of photovoltaic solar panels): responsible for the capture of solar radiation and conversion into electric energy.
2 – Battery bank: responsible for the storage of the converted electric energy, allowing its use at any time, including at night.
3 – Charge controller: an electro-electronic device responsible for charge management of the battery bank and, in some cases, for the management of the energy used by the electric energy consumers.
4 – Solar Inverter (Autonomous): it is the component responsible for the transformation of the direct current generated by the solar panels and stored in the batteries in alternating current, allowing the use of electric energy in equipment made to operate connected to the electric grid. When the equipment works only with direct current (as is the case with most telecommunication devices) there is no need to have an “autonomous inverter” in the isolated photovoltaic system (Off-grid photovoltaic system).
Use of off-grid photovoltaic systems
Nowadays, the use of Off-grid photovoltaic systems is mainly to ‘bring electrical energy to locations not served by the grid’ or to keep some equipment out of the grid, in order to continue operating even when there is a lack of energy in the grid. Public network.
Not recommended use
The electrification of a residence in an urban center through an Off-grid photovoltaic system, while fully possible, is not so attractive from a financial point of view. This is because the costs of the electricity supplied by the public distribution network are much lower than the costs of installing, operating and maintaining an isolated stand-alone photovoltaic system (Off-grid).
However, in a residence in the rural area, when considering the costs of the other options (eg, liquid fuel motor-generator, fuel costs over the years of generator operation, or the costs of providing the network, including the posts, the cables, the transformer, etc.), it may be much more feasible to adopt an Off-grid solar photovoltaic generator. This is why the distributors chose this option to attend the Light for All Program.
Sizing the Off-grid photovoltaic system
An off-grid photovoltaic system can be designed to power any type of load, any power value and any amount of energy. Of course, the more powerful the equipment is to be electrically powered, and the longer the use time, the more energy it consumes, and the greater the Off-grid photovoltaic system should be to meet your energy needs.
And the more powerful an Off-grid system, the greater the financial investment for its deployment. Therefore, it is much more common to feed small loads, such as lighting, telecommunication, and small household items. Feeding a large “irrigation pivot” requires a very costly work, which can make the choice of a liquid fuel motor generator an even cheaper option (even if the fuel and maintenance cost over five years ends. is higher than the cost of installing and operating an off-grid photovoltaic system).
Requirements for designing the components of an Off-grid photovoltaic system
The electrical energy needed to power the electrical equipment that will be used and the available solar radiation at the system installation site.
The first component to be dimensioned is the battery bank, and the following factors must be considered:
1) All energy to feed energy-consuming equipment must be in the batteries; the function of the photovoltaic solar panel is to restore the energy consumed of the batteries (recharge the batteries).
2) Batteries must provide the necessary power for periods of full use of the equipment, ie there must be power to meet the set of equipment for a full day.
3) Batteries must be able to store at least two full operating periods, ie they must store energy for two days of operation, even in cloudy or rainy weather.