Isolated photovoltaic systems are characterized by the total lack of connection to the national grid.
The off-grid systems are facilities that are not connected to the mains: all the energy produced is stored and used on site.
There are different types and dimensions of isolated photovoltaic systems that can go from the simple point light to the telecommunications station, or to the plant to power an entire town in remote areas.
In addition to photovoltaic modules, batteries, inverters and charge controllers are the main components of an isolated system.
Always more interesting and competitive
With the reduction of component costs and the spread of lithium technology, non-grid systems are always more interesting and competitive compared to systems that involve the use of fossil fuels.
The configuration and design of a system without a network requires a detailed analysis of the input variables in the system (average irradiation, equivalent hours of light, orientation, inclination, shading) and of the output variables (extraction of loads from the consumer, time of use, autonomy).
When there is no backup system from other sources, you cannot risk users being left without power – the important thing is to find a technician with sizing experience.
An example for a small network-isolated system in a house
Here is a simple example of a small isolated PV system installed in an isolated house found in the hills of northern Italy (used during the summer):
Consumption is given by a television, a small high-efficiency refrigerator and 3 LED lights. The total power of about 300W, and the house is used during weekends and summer time.
The expected energy demand is approximately 3500 Wh / week; Considering the system losses, we can assume that the required capacity for the batteries is 4000 Wh, guaranteed by 4 units of 15 Ah capacity.
During the time when the utilities are not used, the system will provide to charge the batteries.
The charging system will be implemented using 2 photovoltaic modules of 100 W and a 10 A charge regulator that, combined with the batteries and a 600 W inverter, guarantees the required performance.
The term isolated photovoltaic indicates energy generating facilities that are not connected to an electrical grid and exploit the accumulation of energy.
Isolated photovoltaic systems and their components
For a typical off-grid solar system, you need solar panels, charge controller, batteries, and an inverter. This article explains the components of the solar system in detail.
Isolated Photovoltaic: Components
An off-grid solar system is a bit more complicated and requires the following additional components:
- Charge controller
- Battery bank
- A connected load
- Solar panels
Instead of a grid-connected solar inverter, you can use a standard power inverter or an off-grid solar inverter to power your AC devices.
For this system to work, you need a connection to the batteries.
Optional components Off-grid solar system
Depending on your needs, there may be other components you need, including:
- A backup generator or backup power source
- A transfer switch
- AC load center
- A DC load center
These are the functions of each component of the solar system:
- PV panel: used to convert solar energy into electrical energy. When sunlight falls on these panels, they generate electricity that powers the batteries .
- Charge Controller – A charge controller determines the amount of current to be injected into the batteries for optimal performance. As it determines the efficiency of the entire solar system, as well as the life of the batteries, it is a critical component. The charge controller protects the battery bank against overcharging .
- Battery Bank – There may be periods when there is no sunlight. Cloudy nights, nights, and days are examples of such situations beyond our control. In order to provide electricity during these periods, the excess energy, during the day, is stored in these battery banks and used to power the loads when needed.
- DC-AC Inverter: A DC-AC solar inverter (or simply a “solar inverter”) is an electronic power device that is used to convert Direct Current into Alternating Current. The electricity generated by solar systems is direct current in nature, while most of our household loads require AC power. This conversion is carried out in real time with a very minimal time interval (currently the efficiency of the inverter goes up to 98%). DC loads can be powered directly from the solar system and do not require an inverter.
- Connected load: the load ensures that the electrical circuit is complete and that electricity can flow.
- Backup Generator – While a backup generator is not always needed, it is a good device to add as it increases reliability and redundancy. By installing it, you ensure that you do not rely solely on solar energy for your energy needs. Modern generators can be configured to start automatically when the solar array and / or battery bank does not provide enough power.
- Transfer Switch – When installing a backup generator, a transfer switch must be installed. A transfer switch helps you switch between two power sources. For example, if your solar system is backed by a diesel generator, a transfer switch helps you choose the source of electricity. Transfer switches can be automatic or manual.
- AC Load Center: An AC Load Center is similar to a panel board with all the appropriate switches, fuses, and circuit breakers that help maintain the AC voltage and current required for the corresponding loads.
- DC Load Center: A DC Load Center is similar and includes all appropriate breakers, fuses, and circuit breakers that help maintain the required DC current and voltage for the corresponding loads.
What is isolated photovoltaic?
Systems ailada photovoltaic PV are a convenient solution for electricity in places where it can not connect to the utility grid or the connection is expensive. Its applications are many and varied, allowing the electrification of houses, apartments, warehouses, farms, livestock …
An isolated photovoltaic installation network must guarantee the supply of energy even in the worst climatic conditions because there is no other source of energy.
There are isolated photovoltaic installations for a variety of network applications such as the use of pumping power transmission stations, electrification of museums, cabins, farms … in many parts of the country such as Valladolid, Palencia, Burgos, Ávila, Bizkaia, Tenerife (Spain and in other countries).
Our facilities have measurement visualization systems and control devices necessary to facilitate the monitoring of the plan that is carried out:
- Hydrometer: determines the density of the battery electrolyte.
- Charge indicator regulator
This installation has the following advantages in mounting:
- You do not need any permits from adjoining properties to avoid problems with neighbors and installation delays.
- The dimensions of the panels are small and can be easily installed on the facade, the roof, the structure or the ground … with the only requirement to receive sunlight.
- need to install a medium voltage power line or transformer.
The price per kWh in this type of installation is higher than that obtained in the conventional electrical grid, so in photovoltaic solar insulation it is necessary to optimize the energy consumption of the loads.
Applications of isolated photovoltaic systems
Photovoltaic energy is the direct transformation of solar radiation into direct current electricity. Solar radiation is captured by semiconductor devices called photovoltaic cells, which have the ability to absorb photons of light and emit electrons.
When these free electrons are conducted, the result is an electric current, also known as electricity. Therefore, photovoltaic energy is a renewable energy because it comes from an inexhaustible source of energy, the Sun, a source that is also a clean, sustainable and free resource.
We have photovoltaic systems that are directly connected to the main electrical grid and also that are isolated from the grid. These isolated systems of current generation do not need to be connected to a main electrical network to produce energy from the Sun, hence the term “isolated”. They are usually found in areas where access to electricity is restricted
Scheme of operation of an isolated photovoltaic system
Installation is simple and convenient and offers the ability to use free energy from the sun, avoiding generator noise and diesel fuel costs, as well as harmful exhaust gases. It is sustainable and respectful with the environmenWe produce electricity during the day that we consume instantly and, if we want, we can store it and consume it later.
Isolated installations must be designed according to the energy (electrical) needs of the user to optimize the photovoltaic plant.
It must be properly studied and designed to discover what specific types of devices and instruments are best for this consumption.
Regarding its implementation, as its name implies, it is mainly used in isolated areas without a power grid connection and where electricity is needed. It is highly recommended, sometimes almost essential, for the following applications:
SOLAR PUMPS FOR AGRICULTURE, LIVESTOCK, INDUSTRY AND COMMUNITIES.
The solar water pump starts to work directly during the hours of the day when the amperage produced by the solar panels is sufficient for the operation of the pump.
Solar PV Pumping System
The system consists of solar panels, a converter and a submersible pump that will draw water throughout the day and be stored in a swimming pool, storage tank or similar storage.
This system is used in gardens where the water is taken from a well to a storage place, thermos, tank or pool, which is filled and allows irrigation when necessary. Or the water can be automatically led into cattle canals. It could even be implemented to provide water to industries, or homes isolated from the main electrical network, or to transport water between tanks.
POWER SUPPLY FOR AGRICULTURAL, LIVESTOCK, INDUSTRIAL AND COMMUNITY USE .
This system offers energy supply for isolated areas without a main electricity grid, which is very important for developing countries and electrification of rural areas, with a low cost of installation and maintenance. It can also be used in ship lighting, greenhouses, refrigeration, window automation, milking systems, etc.
SIGNAL POSTS AND LIGHTING.
It is a very economical resource used for traffic lights, streetlights, warning signs on roads, airports and cities, oil rigs, tunnels, billboards, etc.
TELECOMMUNICATIONS AND CONTROL.
Radio and television antennas, telephone equipment, antenna, and transmitting stations for data, such as weather, seismic and watercourse levels, can be powered by isolated solar photovoltaic energy, which is safe and economical.
We can find another of its applications in industrial development, such as telecommunications, antennas, surveillance systems in oil and gas refineries, as well as in the cathodic protection of pipelines, oil pipelines and other types of pipes, highly reliable systems are needed.
Shelter equipment and leisure areas, battery charging for caravans and boats, etc.