Device type
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Autonomous inverter. Voltage and power converters that are not connected to an external electrical network. They are supposed to be used as part of autonomous photovoltaic systems - such inverters generate electricity, which is spent exclusively for the needs of the household. It can be consumed directly by household appliances or accumulated in batteries. This type of inverter is often called off grid.
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Network inverter. Inverters operating synchronously with the external power supply network. They are designed to convert solar energy into alternating power with the parameters of the general network. Grid-connected inverters are used in battery-free systems - all generated energy is used for own consumption, and the excess is transferred to the network at a “feed-in tariff”. To do this, some indicators of generated electricity are adjusted, in particular, amplitude differences are eliminated, the network frequency is equalized, etc. Grid-tied inverters are also known as on-grid inverters.
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Hybrid inverter. Battery-grid inverters are peculiar hybrids of autonomous and network converters. Actually, this is where the name hybrid comes from. Inverters of this type work with battery chains, and excess electricity is sent to the general network. This ensures the energy independence of the system based on solar panels with the ability to use the energy a
...ccumulated in the batteries without disconnecting from the network. For example, if DC power is prioritized, power is primarily supplied from batteries, and any energy shortages are supplied from the external grid. This comes in handy in case of bad weather conditions or insufficient power generated by solar panels. If electricity is generated in excess, the excess energy is released into the general network at a “feed-in tariff”.
— Inverter for campers (motorhomes). Such narrow-niche inverters usually work in conjunction with a branded charging station - while staying at a campsite, it charges the vehicle’s battery. And while driving, such inverters are connected to the car’s alternating power generator and with their help, the energy reserves in the battery cells of the charging station are replenished.Maximum charge current
The maximum amount of direct current in amperes that the inverter can convert. If the solar panel produces a current exceeding this value, the inverter simply does not use it. This is often justified when connecting an inverter to high-power solar panels - the maximum input current of the inverter is reduced to acceptable values so that moderate-sized wires can be used to transmit energy.
Total battery capacity
The total capacity of the batteries connected to the inverter, expressed in ampere-hours (Ah). The larger the capacity, the longer the battery life will be, all other things being equal. For example, a 100Ah battery can theoretically deliver 100A for one hour, or 10A for 10 hours.
Separately, we note that batteries with the same rated voltage can be compared by capacity in ampere-hours - this is due to the characteristics of the ampere-hour as a unit of capacity. If you need to compare batteries of different capacities, you need to use data in watt hours (see below). And using special formulas you can calculate the capacity in Wh based on the capacity in Ah and the rated voltage of the battery.
Total battery capacity
The total capacity of the connected batteries in watt-hours (Wh). In fact, this is the amount of energy that is supposed to be stored in the battery. The larger the capacity, the longer the battery life of the connected equipment will be, all other things being equal. On the other hand, this parameter also affects the dimensions, weight and price of the battery. Based on the capacity in watt-hours, batteries can be compared with each other.
Max. power
The maximum allowable input power from solar panels, expressed in kilowatts (kW). Let us remember that 1 kW contains 1000 W.
When selecting an inverter based on this indicator, they are based on the total power of the solar panels involved in generating electricity. Moreover, it often makes sense to select models with an inverter input power slightly less than the maximum power of solar panels - for example, if they are shaded part of the time or for other reasons do not receive enough sunlight during the day. The power of the solar battery should not exceed the power of the inverter by more than 30%. However, for some inverters the excess can be only 10%, while for others it can be up to 100%. It is better to clarify this point in advance.
Operating voltage PV
The operating range of the inverter is usually located between the starting voltage and the maximum voltage. This interval is indicated in volts.
Control interfaces
Connection interfaces provided in the inverter design for solar panels.
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RS232. A specialized communication interface used to directly connect the inverter to a computer. As a rule, the interface provides the ability to monitor solar generation systems around the clock using a local network. Also, the RS232 connector can be used to communicate several inverters with each other, or, less often, for software updates or service testing.
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RS485. A connector often used to connect several inverters to a central hub, which, in turn, connects to a computer. This connection can be useful for setting up a solar generation system or sending monitoring data over the network.
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USB. A standard USB port is often used for configuring equipment via a wired connection to a computer or for inverter firmware updates.
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LAN (RJ45). The presence of a LAN connector (RJ45) in the inverter design. Such ports are standardly used for wired connections in computer networks using a twisted pair cable.
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Wi-Fi. Wi-Fi communication module for wireless connection of the inverter to a computer, laptop or mobile phone. Using specialized software, you can receive monitoring data from the inverter directly “over the air” - transmitting information over a Wi-Fi network eliminates the
...fuss with wires.
— Bluetooth. Option to wirelessly pair the inverter with smartphones, tablets or laptops via Bluetooth. Thanks to data synchronization, the user will be able to monitor equipment performance and remotely control the inverter within range of the Bluetooth wireless network.Protection
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Overload protection. A protection system against connecting an off-design load whose power consumption exceeds the capabilities of the inverter for solar panels. In such situations, the power to the outlets is automatically turned off, since overloading the device promises failure and even fire. Triggering of the protection is usually accompanied by a sound and/or light signal.
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Overheat protection. This protection is triggered when the temperature inside the inverter rises critically. When such situations occur, the device turns off, which avoids breakdowns. In the future, some models will automatically turn on when the temperature normalizes, while others must be turned on manually. Note that overheating is caused not only by malfunctions, but also by completely normal reasons - for example, long-term operation at high air temperatures. Typically, overheating protection is accompanied by a sound and/or light signal.
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Protection against ↑ or ↓ battery voltage. A protection system that prevents the inverter from being supplied with excessively high or excessively low voltage from the batteries. When the operating voltage range is exceeded, the device automatically turns off to avoid breakdowns and other troubles. A sound and/or light signal can warn of protection activation.
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Short circuit protection. Protec
...tion that is triggered when the output current increases critically (for example, due to a foreign metal object getting between live parts of the load). To avoid breakdowns and failure, the power at the inverter output is automatically turned off. Triggering of the protection system is usually accompanied by a sound and/or light signal.
— Reverse polarity protection. Protection system in case of incorrect polarity of connection. If the “plus” and “minus” do not match, the inverter is disconnected from the power supply in order to avoid damage to the electronic components. Notification of protection activation is often provided by a sound and/or light signal.
— Protection class. The class of protection against dust and moisture provided by the inverter housing for solar panels. Indicated according to the IP standard by two numbers: the first (from 1 to 6) means resistance to penetration of foreign objects and dust, the second (from 1 to 8) - protection from moisture. The higher the number, the higher the level of protection provided. Also note that instead of the first digit in the designation of the protection class, “X” may be indicated - for example, IPX7. In this case, the device is not certified for dust protection, although in fact the level of such protection may be quite high. So, in the example with moisture resistance “7”, the case can be completely immersed in water - which means it is closed very tightly from dust.
The IP protection level is especially important to consider when choosing models for outdoor use and installation in rooms with high humidity levels - they are the ones most susceptible to adverse environmental influences. A high IP class will guarantee stable operation of the inverter for solar panels in such difficult conditions.Operating temperature
The range of ambient temperatures in which the solar panel inverter is guaranteed to maintain normal operation. Here it is necessary to focus on the expected minimums and maximums of temperatures. Moreover, for operation in the cold season, it is worth paying close attention to models with the ability
to operate at sub-zero temperatures.