Hybrid inverter for solar panels: the choice and principles of the device

Power supply systems with simultaneous use of traditional power supply and electricity from the sun - economically sound solution for private household, cottage, holiday villages and industrial premises.

An indispensable element of the complex is a hybrid inverter for solar cells, which determines the voltage supply modes, ensuring uninterrupted operation and efficiency of the solar system.

For the system to work efficiently, you need not only to choose the optimal model, but also to connect it correctly. And how to do it - we will analyze in our article. Also consider the existing types of converters and the best offers on the market today.

Evaluation of hybrid inverter features

The use of renewable solar energy in combination with a centralized power supply provides several advantages. The normal functioning of the solar system ensures the smooth operation of its main models: solar panels, charge controller, the battery, as well as one of the key elements - the inverter.

A solar system inverter is a device for converting direct current (DC) from photovoltaic panels into alternating electricity. It is on the current voltage of 220 V works household appliances. Without an inverter, power generation is meaningless.

It is better to evaluate the capabilities of the hybrid model in comparison with the peculiarities of the work of its closest competitors - autonomous and network "converters".

Network converter type

The device operates on a common electrical load. The output from the inverter is connected to consumers of electricity, the speaker network.

The scheme is simple, but has several limitations:

• operability at availability of alternating current in the network;
• the mains voltage must be relatively stable and correspond to the operating range of the converter.

The variety is in demand in private homes with the current "green" tariff for electrification.

Autonomous device option

The device is powered by batterywhich receives charge from the solar panels through the MPPT controller. The system uses different types of batteries, including high-tech lithium batteries.

At the maximum “filling” of the accumulator, excess energy is transmitted to the input of the inverter, the output of which is connected to the end users of the AU.

In the case of a lack of solar activity, energy is taken from the batteries and is "converted" through the voltage inverter.

Features of the autonomous installation:

• the possibility of independent operation in the absence of mains AC;
• some models support the mode of operation at the "green" tariff;
• Efficiency of installations - 90-93%.

To ensure the absolute autonomy of the object requires accurate power calculation of heliopanels and sufficient battery power consumption.

Hybrid inverter type

The model differs from the above described devices by a special “architecture” of manufacture. Inside, there is a special wiring diagram that allows the converter to operate in parallel with the current source (network, generator).

At the same time, the load is powered from the central network and solar cell, with the priority function assigned to the DC supplier.

Competitive advantages lie in the versatility of hybrid type inverters:

1. Network - a kind of roomy battery with an efficiency of 100%. All surplus produced by photovoltaic plates can be redirected to the central grid at a "green" tariff.
2. Uninterrupted power supply. When the main power supply is disconnected, the system is rebuilt into an autonomous mode, protecting all consumers from voltage surges.
3. Increase the network power limit during peak loads by adding energy from the battery-inverter complex.

When the heliocomplex consumption declines, it switches to charging mode and after a while is again ready for use. The double power function may be indicated: Smart Boots, Power Shaving, Grid support.

Adding power occurs according to the following principles:

• if the power used is lower than the maximum network consumption, then in addition to the load power, the storage battery is charged;
• in the absence of voltage in the network consumes electricity generated from the battery and converted by the inverter;
• if the load exceeds the limit value of the network power, then the deficiency is compensated by the accumulated electricity from the solar battery.

The listed modes of operation are capable of supporting hybrid models with a charger.

Varieties of current transducers

Choosing the "heart" of the autonomous power supply system, you should correctly compare the tasks assigned to the equipment with its potential.

The main features of the classification of hybrid inverters are: an algorithm for changing operating modes, the shape of the output voltage and the possibility of servicing a single or three-phase network.

Comparison of BBP and hybrid installation

Some companies involuntarily mislead the consumer, calling the uninterruptible power supply (FOB) unit a hybrid inverter. It would seem that both devices perform similar tasks, but there is a significant difference.

BBP is a charger inverter. The module primarily ensures the expenditure of energy from the photovoltaic plant, and when it is deficient, it switches to power consumption from the network.

The functioning of the system in the "jerk" mode provokes an additional cycling of the battery and accelerates its wear. In most low-cost BBPs, the threshold voltage is set without the possibility of regulation.

In hybrid inverter models for solar cells, such jumps are excluded - the unit adjusts to the required power and works simultaneously with different current sources.

You can independently choose priority consumption. As a rule, the emphasis is on the expenditure of energy from solar panels. In some hybrid units, there is an option to limit the power coming from the city network.

Varieties of inverter waveform

Solar cell current transducers are classified by type of output signal.

There are:

• pure sine wave;
• modified sine (quasi-sinusoid);
• meander.

The last option is practically not used in practice, since a sharp change in polarity causes malfunctions in the equipment.

What is a pure sine wave?

The converter provides a high quality signal that exceeds the shape of the network current. This is the best option to ensure the operation of "sensitive" equipment: heating boilers, compressors, electric motors, medical equipment and devices based on transformer sources power supply.

Quasi-Sine Features

Transmission of energy signal in the form of a modified sine wave can reduce the efficiency some appliances, provoke noise, cause interference or cause damage equipment.

When powering low-frequency transformers, asynchronous, synchronous motors seen loss of power by 20-30%. This "defect" is converted into thermal energy, overheating the devices.

Inverters with a pseudo-sinusoidal signal are compact and affordable. Their use is appropriate for powering devices without inductive loads, designed to consume the active components of electrical power.

This group includes: thermoelectric heaters, incandescent lighting systems and other resistive structures.

The shape of the output signal is indicated in the passport of the inverter or bespereboynik. Possible notation: “Back” - a guarantee of the absence of a pure sine, “Smart” - the probability of obtaining a quality current at the output.

Some manufacturers in the accompanying document note the harmonic coefficient (nonlinear distortion index). If the parameter is less than 8%, then the unit produces an almost perfect sine.

Single phase and three phase models

Single-phase inverters are predominantly embedded in a household photovoltaic system with a standard voltage of 220V.

The range of the output voltage when connected to one phase in different models ranges from 210-240V, the output frequency is 47-55 Hz, the power is 300-5000 watts.

Single-phase inverters are available for standard battery voltage values ​​of 12, 24, and 48 V. In order for the converter not to function at the limit of possibilities, it is necessary to coordinate the power of the “converter” with the voltage of the solar battery or battery.

Three-phase inverters are used to supply three-phase current, providing power to the electric motors. Primary application - production, workshops, commercial purpose.

Three phase inverters are distinguished by high power (3-30 kW), a wide range of output AC voltage (220V / 400V).

On the market there are also combined models. These include single-phase inverters with the ability to synchronize the outputs of the converter with a phase shift - this allows you to supply three-phase loads. We considered all types of technology for current conversion from solar panels in our other article.

Solar inverter selection options

The efficiency of the converter and the entire electrical supply system largely depends on the correct choice of equipment parameters.

In addition to the above characteristics should be evaluated:

• output power;
• type of protection;
• operating temperature;
• installation dimensions;
• Efficiency;
• availability of additional functions.

Consider further all these characteristics in more detail.

Criterion # 1 - device power

The value of the "solar" inverter is selected on the basis of the maximum load on the network and the estimated battery life. In the starting mode, the converter is capable of delivering a short-term increase in power at the time of commissioning capacitive loads.

This period is typical when turning on dishwashers, washing machines or refrigerators.

When using lamps of lighting and the TV the low-power inverter on 500-1000 W will approach. As a rule, the calculation of the total power of the equipment being operated is required. The desired value is indicated directly on the instrument case or in the accompanying document.

Criterion # 2 - level of protection

A quality solar inverter should have several protection levels. Possible options: forced cooling system, short circuit warning, protection against failures and voltage surges in the network.

It is important - the presence of a sealed reinforced case, preventing the ingress of dust particles, moisture. The electrical equipment protection rate is standardized according to IEC-952 standardization.

For conditions of operation in the open air, models with the IP65 index are suitable - the strength and reliability of the inverter allows its use in the external atmosphere.

Criterion # 3 - working temperature and dimensions

A wide range of values ​​is an indicator of decent quality of the inverter assembly. The value of the indicator is particularly relevant when placing the converter in an unheated room.

Weight is an indirect indicator of the quality of the inverter. There is an opinion - the heavier the converter, the more powerful it is. This is due to the presence in the high-power equipment of the transformer.

In "lightweight" models, the absence of a transformer can cause the inverter to break when a high starting current is applied.

Criterion # 4 - Efficiency

Experts recommend purchasing "converters" of current with an efficiency of 90%. Only with such a parameter will the solar system work efficiently, and its arrangement is expedient. Loss of 10% of solar energy is an unacceptable "luxury".

Additional functionality. Advanced features affect the cost of equipment and are not always in demand. However, some options justify the money spent.

The useful and necessary "devices" include:

• automatic addition of inverter power to the electricity network;
• adjustment of the charging period of the battery;
• selection of the priority current source;
• maintenance of work with batteries of different types (alkaline, lithium iron-phosphate, helium, AGM, acid);
• possibility of combined work with a network converter;
• setting the voltage indicator - warning of "surges" of the mains voltage;
• the possibility of upgrading the inverter by updating the firmware.

Modern converters can be connected to a PC for programming and monitoring.

Overview of popular hybrid converters

Among consumers, good reviews were received by inverters of foreign companies: Xtender (Switzerland), Prosolar (China), Victor Energy (Netherlands), SMA (Germany) and Xantrex (Canada). Domestic representative - MAP Sine.

Xtender Multifunction Inverter Line

Xtender's hybrid Studer transducer is the epitome of Swiss quality standard in power electronics. Solar inverters of the Xtender series are distinguished by their exponential strength characteristics and extensive functionality.

Variety of models: ХТS - low-power representatives, HTM - medium power models, ХТН - high-power inverters.

Each series of hybrid converters Xtender has the following characteristics and options:

• pure sine wave feed;
• "Mix" power to the network from the battery;
• while reducing the mains voltage consumption from the central power supply is reduced;
• two priority selection modes: the first is “soft” with network feed within 10%, the second is full switching to the battery;
• variety of instiller settings;
• management of the backup generator;
• standby mode with a wide range of regulation;
• remote monitoring of system parameters.

In all versions there is a Smart Boost function - connection to different “suppliers” of power (generator set, mains inverter) and Power Shaving - guaranteed coverage of peak loads.

Prosolar Optimum Converters

The Chinese-made model has good characteristics and an acceptable cost (about 1200 cu). The converter optimizes the operation of solar cells, saving unused energy in the battery.

Distinctive features:

• option tracking the point of the boundary power of the solar battery;
• information LCD display with display of system operating parameters;
• 3-level battery charger;
• adjustment of the maximum current up to 25A;
• communicator inverter.

The converter is connected to the PC via software (supplied as a set). It is possible to upgrade the inverter through innovative flashing.

Sinusoidal inverters Phoenix Inverter

Phoenix inverters meet high requirements and are suitable for industrial applications. The Phoenix Inverter series is released without a built-in charger.

Converters are equipped with a VE.Bus information bus and can be operated in parallel or three-phase configurations.

The power range of the model range is 1.2-5 kW, the efficiency is 95%, the voltage type is a sinusoid.

Competitive advantages:

• technology "SinusMax" supports the launch of "heavy loads";
• two energy saving modes - load search option and lower idle current;
• presence of alarm relay - warning of overheating, insufficient battery voltage, etc .;
• Setting programmable parameters via PC.

To achieve high power, parallel connection to the phase of up to six converters is possible. For example, a combination of six devices with a nominal value of 48/5000 is capable of providing an output power of 48kW / 30kVA.

Domestic devices MAP Gibrid and Dominator

MAP Energia has developed two versions of a hybrid converter: Gibrid and Dominator.

The equipment power range is 1.3–20 kW, the time interval for switching between modes is up to 4 ms, the possibility of “pumping” electricity into the city network is provided.

General characteristics of voltage converters Gibrid and Dominator:

• a torus-based transformer;
• input voltage stabilization is absent;
• power swap mode;
• output - pure sine;
• generation of excess energy in the network;
• limiting the current consumption at the input of the AU;
• class IP21;
• consumption in the "sleep" mode - 2-5W.

The efficiency of converters reaches 93-96%. The devices have successfully passed tests for use at ultra-low temperatures (the limit value is -25 °, a short-term reduction to -50 ° C is permissible).

Possible wiring diagrams

When building a photovoltaic complex combined with a central network, there are various options for connecting the inverter.

Option # 1 is a circuit with a DC charge controller

The most popular option, where the charging of the battery is carried out through the solar controller MRRT (analysis of the peak power point).

Solution features:

• efficient use of renewable energy in the presence / disconnection of the network;
• the ability to activate work from the solar system after the battery is low.

And another solution is to slightly increase the energy conversion losses in the “controller-battery-inverter” segment.

Option # 2 - hybrid and network converter circuit

Network converter at the output of the battery inverter. According to the diagram, two converters are connected to different solar batteries.

The hybrid converter is connected to an optional photovoltaic panel for recharging the battery, the mains is connected to the main solar module.

System Features:

• smooth operation regardless of the presence of a central network voltage;
• high efficiency and minimization of losses on the DC side due to the sufficient voltage level of the solar battery;
• batteries almost always function in a buffer mode, which increases their service life;
• the use of hybrid inverters, designed to charge the battery from the output;
• the need to adjust the network inverter

The total power of the mains converter should not exceed the power of the hybrid "converter" - this allows you to recycle the energy of solar panels in the event of battery discharge, disconnection of the network.

Regardless of the chosen scheme, when connecting the inverter should consider a number of nuances:

1. Wired connections for DC should not be long. It is desirable to place the inverter in proximity (up to 3 m) from solar panels, and then “build up” the main line with AC.
2. The converter must not be mounted on combustible materials.
3. The wall inverter is located at eye level for easy reading of information from the display.

There are special requirements for connecting models with a capacity of more than 500 watts. The connection must be tight with reliable contact between the instrument terminals and the wires.

Also on our site there are other articles on solar energy and the connection of individual components and modules when building an autonomous system.

We recommend to read the following materials:

• Connection diagram of solar batteries: to the controller, to the battery and the systems served
• Solar battery charger: the device and the principle of operation of charging from the sun
• How to make a solar battery do it yourself: ways to assemble and install a solar panel

Conclusions and useful video on the topic

The concept of "hybrid inverter", its device, functions and versions:

An overview of the features, modes of operation and efficiency of using the 3 kW InfiniSolar multifunction converter:

Designing a solar power system is a complex and demanding task. It is better to entrust the calculation of the required parameters, selection of the composite components of the solar complex, connection and commissioning to professionals.

Mistakes can lead to system failures and inefficient use of expensive equipment..

Selecting the best converter option for the functioning of an autonomous power supply system based on solar energy? Do you have questions that we have not touched on in this article? Ask them in the comments below - we will try to help you.

Or maybe you noticed inaccuracies or inconsistencies in the material presented? Or do you want to supplement the theory with practical recommendations based on personal experience? Write to us about it, share your opinion.