Solar systems around the world are developing at a tremendous pace. The International Energy Agency in its annual report noted that in 2016 the number of commissioned solar power plants for the first time exceeded the number of coal.
The heart of the solar energy system is an inverter for solar panels, the task of which is to transform a constant type of current into alternating current. We will tell you how to choose the best option for the device and how to correctly install it. Based on our recommendations, you can assemble an impeccably functioning mini-power station.
Types of inverters for solar panels
Without an inverter, the energy generated by the solar system will be completely useless for domestic needs. There are 3 types of inverters by type of use:
- autonomous;
- network
- multifunctional.
Inverters of the first type are designated “off grid”. They are connected to the solar module, are part of a separate photovoltaic system and do not in any way contact with an external electrical network. Their power varies between 100 - 8000 watts.
Synchronous or network inverters operate synchronously with a centralized power supply system. Converters with the designation “on grid” not only perform the role of a converter, but also correct such network parameters as amplitude differences, frequency indicators, and others.
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To organize an autonomous solar power station, a complex of equipment is required, one of the components in it is an inverter
The duty of the inverter is to convert the direct current received by the solar solar station to the alternating current required to power household appliances
The operation of the inverter in the scheme of systems with solar batteries can perform a conventional frequency converter, which is dusting dust on mezzanines. However, buying it specifically for the device of a mini-power plant on solar panels is pointless, it has more functions than necessary
Solar panels generate energy on average of 12 and 24 V, a maximum of 48 V. However, to power most household units, you need 220 V, which provides an inverter
If the inverter is equipped with an uninterruptible power supply, it will automatically switch the system to power from a centralized network on cloudy days and translate it back into solar
You can do without an inverter if the energy received by the solar battery is needed only for charging mobile devices, welding machines, street lighting on solar panels
The modular connection principle allows the use of a group of inverters instead of a single device, if there is a need for a current supply of 380 V
The presence of a transformer in the inverter circuit is not necessary. Because of it, the price rises and the system becomes more complicated. True, if you need a high quality signal, it is better to buy an inverter unit with it
A complex of equipment for a solar power station
Equipment for converting direct current to alternating current
Standard frequency converter
Two-panel solar power station
Uninterruptible Inverter
Operation of the solar panel without inverter
Ability to use a group of inverters
Inverter device with transformer
If there is a problem in the external network, the inverter will automatically shut down. Such inverters accumulate electricity in batteries.
If the total power of the devices used in the house is less than the potential capabilities of the solar power station, then the excess generated electricity goes into external electrical networks. If the power is not enough for the normal operation of household appliances, then recharge from the outside is carried out.
The inverter parameters on the AC side are determined based on the total power consumption of all devices connected to the consumer's electrical network. On the DC side, the inverter is selected based on the rated power of the solar panels
In the absence of voltage, power is supplied from a charged battery. In the case when batteries are not included in the system, the energy produced by the solar power plant goes into a common network.
Network photoelectric inverters with high efficiency use the energy received from solar panels. They are a guarantee of stability of power supply and are characterized by high efficiency exceeding 90%
Hybrid or multifunction inverter - reliable equipment. It combines the properties of the first two converters, has a large number of settings. This is the best option for building a home solar station, but also the most expensive.
All existing solar inverters are divided into types and according to the output voltage. Depending on this parameter, they are sinusoidal and meander. Since the first value of the output voltage is almost the same as that of the power supply network, this is a good option when there is a highly sensitive technique in the house.
The constant voltage value is a guarantee of safety for home electrical equipment. Graphically, the waveform at the output of such a sinusoidal type inverter is depicted as a pure sine wave.
When operating the equipment, the best shape of the meander is the perfect sine. This is especially important for telecommunication equipment, medical equipment, high-precision measuring devices, therefore, even despite the high price of complex inverters, there are no other options in this case. Manufacturers indicate information about the shape of the output signal in its characteristics
Meander or non-sinusoidal converters, unlike sinusoidal ones, have a signal geometry at the output in the form of rectangular pulses, the so-called modified sine. Inverters of this type cannot be used for certain types of load, but for devices using the active component of power, they are quite suitable.
Inverter selection criteria
When choosing such a solar system element as an inverter, not only the geometry of the output signal is important, but also its power. Experts advise to equip solar panels with converters whose rated power is higher than the total power available in the technology volume by 25-30 percent.
It is also necessary to take into account the load arising from the simultaneous switching on of several devices with high starting power.
Another criterion when choosing an inverter is its efficiency, which determines the energy loss of the accompanying processes. Depending on the model, it has a different value, which is in the range of 85-95%. The best choice is an efficiency of at least 90%.
Inverters are both single-phase and three-phase. The former are of lower cost, but their choice is justified when the power consumption is less than 10 kW. The voltage they have is 220V, and the frequency is 50Hz. Three-phase inverters have a wider voltage range - 315, 400, 690V.
Manufacturers of quality equipment complete their products with output transformers. There is a relationship between the weight of the inverter and its technical characteristics - if for every kg of its mass there is 100 W of power, then the transformer is included in its circuit
The number of inverters in the system may also be different. In this matter, the following recommendations should be guided: if the power of solar panels does not exceed 5 kW, then one inverter is enough for such a system. For larger batteries, 2 or more inverters may be required. It is optimal when one inverter is needed for every 5 kW.
Hybrid inverters are used to operate in a network that combines the use of standard electricity and the energy supplied by solar panels. The features of the device and the rules for their selection will be introduced by our recommended article.
Converters can differ from each other in circuits, output signal geometry, and other determining quantities. Separate converters are equipped with chargers. If one of the inverters fails, the system will not stop its operation.
Features of connecting the inverter
The efficiency of the entire solar system depends on the correct connection of the solar inverter. The main thing is to observe the rule: a cable that transmits direct current must have a minimum permissible length and a maximum cross section.
If the consumer is far from solar cells, extend by increasing the electric cable transporting alternating current 220 V. The length of the wire between the inverter and the solar panel should vary within 3 m and not more.
The best option when the inverter is located near the solar panel. Particularly stringent conditions have to be met when connecting inverters that exceed 0.5 kW in power.
The wire connection must be solid, as insufficiently tight connection causes sparking, which can cause a fire. When installing an autonomous inverter to ensure uninterrupted power supply to the facility, the DC circuit must be equipped with circuit breakers.
The best solution when connecting the inverter is to use a hybrid type strapping for both direct and alternating current. The principle is based on a special order of turning on the converter. It includes a controller for solar panels after the batteries are charged.
This solution increases the quality of the equipment. In regions where electricity is often turned off, or in houses located in areas where cloudy weather prevails, this option works very efficiently.
Overview of Inverter Models
Converters for solar panels are produced by many manufacturers, both domestic and foreign. All equipment has different characteristics, quality levels, its own set of functions and technical capabilities.
Inverters from a domestic manufacturer
A wide range of these products with a power of 800 - 1200 W is produced by the Russian manufacturer MAP "Energy".
The company produces several lines of inverters:
- Sine wave inverters with a pure sine waveform - MAP SIN.
- Sine-wave converters with the function of selecting an additional amount of energy from batteries - MAP HYBRID.
- Three-phase inverters - MAP HYBRID 3 phases.
Inverters manufactured by this company can charge all types of batteries. To do this, they have a large capacity charger.
The achievement of the company is an inverter of record power - 20 kW, withstanding the largest load of 25 kW. This model can provide reliable power to a large apartment building with many appliances.
Inverters MAP "Energy" is used not only in private households, but also in many industries. They are used in medicine, construction, weather stations
Schneider Electric Conext Converters
The French company Schneider Electric produces inverters with high performance characteristics that allow them to be used in different climates.
The coating of the body, which has high corrosion resistance, allows you to successfully pass testing with salt fog. They are designed for solar panels installed both on the roofs of private cottages and apartment buildings.
The manufacturer checks the reliability of his equipment using various methods and tests. The design of Conext inverters lacks electrochemical capacitors, which is a guarantee of long-term operation.
Conext inverters, even at maximum loads, have an efficiency of 97.5%. Separate models are equipped with a distribution block, so there is no need to install an external electrical panel
A wide range of products allows you to choose the right model for solar systems with a capacity of 3 - 20 kW.
TBS Electronics Inverters
This Dutch company, which has been present on the market since 1996, produces both low-power and more powerful sinusoidal converters for Poversine solar panels with a rated power of 175 to 3500 watts.
The photo shows a model of a professional inverter Powersine PS3500-24. It can be used to provide uninterrupted power to heating boilers, pumps, computers, and other small loads. It is equipped with reliable electronics, a high-strength metal housing
The Powersine line is characterized by a very pure sine wave at the output, so the use of these inverters guarantees the competent and long-term operation of highly sensitive devices. The equipment is equipped with protection against short circuit, temperature surges, overloads. With these inverters, loads up to 500V can be launched with a starting force that exceeds tens of times the rated power.
Kostal Network Inverters
The company produces innovative high-quality inverters with power from 1.5 to 20 kW, both single and three-phase. The design includes an AC switch that works automatically, MPP trackers, monitor, S0 counter and many other options in the basic configuration. All this makes it possible to introduce an inverter into the "smart home" system.
Kostal inverters are simple both in operation and in installation. Built-in panel - informative and understandable, allows you to monitor its operation
Due to the high quality of the housing material, the converter is installed both outside and inside the house. The assembly is carried out in Europe, so the quality meets European standards. Manufacturer's warranty - 5 years.
ABi-Solar Inverters from Taiwan
These inverters, manufactured in Taiwan, are represented in our market by a series of autonomous SL / SLP converters, autonomous network hybrid inverters (NTR), and a line of NT hybrids.
Autonomous converters are equipped with solar charge controllers. This equipment is endowed with triple functionality - it works as an inverter, controller, charger.
The design includes a liquid crystal display that allows you to control the main parameters of the solar system. The efficiency of SL / SLP inverters is about 93%. The SLP models have dust protection.
The inverter from the new ABi-Solar HTP series belongs to the budget option. It works only with a battery. The NT series is particularly popular, including single and 3-phase hybrid inverters, which stand out for their excellent build quality.
Converters SL0912 and SL1524 are also low-cost. They work in 2 modes - household uninterruptible and with solar panels. They have 2 modes of voltage maintenance: from 180 to 260V and from 100 to 300V.
The second mode allows you to increase the battery life due to less use, but can only power equipment that is not very sensitive to the quality of electricity.
The ABi-Solar SL 1012 PWM inverter has a capacity of 800 V. The output current has an unmodified sine wave. It can be used for sales produced by solar panels of electric energy at the “green” tariff.
ABi-Solar inverters make it possible to increase the operating temperature range of batteries and automate the charge-discharge process.
GoodWE Network Inverters
This Chinese company produces network inverters of various capacities and delivers them to the market at a low price.A special program is attached to the inverter, which allows you to calculate the solar system taking into account the location of the solar panels in relation to the cardinal points and other landmarks.
It is possible to monitor the operation of the converter via a tablet or smartphone, but first you will have to install an application specially designed for this based on the Android operating system.
Here, the manager of the selling company talks about the principles of choosing an inverter:
This video highlights the inverter connection issue:
The photoelectric network inverter, as an integral part of the solar system, allows you to get complete independence from centralized power supply and rising prices for electric carriers.
Smart systems, including a network converter, make the process of energy consumption affordable, reliable and manageable. At the same time, comfort in the house is not disturbed in any way.
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