All grid-connected inverters must be anti-islanding, as required by international standards and specifications. Why? Because the islanding effect is dangerous. If the grid suddenly goes down and the inverter is not island-proof, it will continue to supply power, creating an island effect. When the power grid is restored, it may generate a large surge current, which can damage the inverter and power equipment, and may also injure maintenance personnel.
From the technical specifications, class B inverters must be able to find the islanding situation quickly, and immediately cut off the connection with the grid, this action should be completed within 2 seconds, but also send a warning signal. Moreover, the islanding protection has to work well with the line protection on the grid side.
Therefore, the grid-connected inverters now have an anti-islanding function, which is to ensure the safe operation of the photovoltaic system must have the function!
Some people think that solar inverters have to be repaired frequently and cost a lot of money, which may discourage many people from using solar systems.
It is quite the opposite when it comes to solar inverters. These devices are structured to be very robust, inexpensive in maintenance, and highly reliable. They could even withstand very bad weather conditions and usually bear a general warranty of up to 10 years or more. Daily maintenance is so simple: just wiping off the dust from the inverter, taking a glimpse of whether it has bumps and damages, and seeing that the ventilation is good enough so as not to have the inverter covered. Occasionally, check the cables for assurance that they are plugged in and not loose. If the solar inverters makes some uncommon noise or reflects certain fault codes, then that could be the signal to call for help.
Overall,solar inverters are not a hassle to maintain and don't cost much money.
Most of the specifications for inverters give the "AC output voltage," and that makes many think that is the voltage this device generates by itself. That is not the case at all. No voltage is produced by the inverter but rather its grid voltage as a guide, and its main functionality is to perform the conversion of electrical energy from one form to another. Precisely, most inverters convert DC into AC or change one voltage level of electricity into another. An solar inverters does not generate its voltage; it follows the grid voltage.The inverter is a current-source device and has to be connected with a grid to get the electricity out safely. During operation, it constantly monitors the grid voltage V and frequency F. Whether the inverter can output smoothly depends on whether it can synchronize with these parameters of the grid.
Solar Energy Systems:
Solar panels produce direct current (DC) electricity. An inverter converts this DC power to alternating current (AC) to power home or commercial electrical equipment, or to feed excess power back into the grid.
Battery energy storage systems:
Batteries store electricity that is also direct current (DC). An inverter converts the DC power from the batteries to alternating current (AC) to power electrical devices when needed.
Power adapter:
Many electronic devices (e.g., laptops, cell phones, etc.) require direct current (DC) power, while home outlets provide electricity in alternating current (AC). The inverter in a power adapter converts AC to DC to provide the right voltage and current for the device.
Many people mistakenly believe that solar inverters stop completely during a power outage, but it's not that simple. It's true that most grid-tied solar systems automatically shut down during a power outage for safety reasons, preventing harm to the crews servicing the grid.
But some inverters, such as hybrids or inverters with batteries, will still operate when the power goes out.
These special inverters are partnered with energy storage devices such as batteries. Normally, they convert solar energy into usable electricity, charging the batteries in the process. Once the power goes out, they seamlessly switch to battery-powered mode, allowing your home's solar power to continue to shine without a hitch.
Not necessarily. While a higher DC string voltage can improve the overall efficiency of your system, that doesn't mean it will always result in more power generation. Here are a few key points to explain this phenomenon:
MPPT operating voltage range:
The inverter has a specified MPPT operating voltage range. Within this range, the inverter can most efficiently convert the DC power generated by the solar panels. If the DC string voltage falls within that range, then the inverter will be more efficient, hence potentially increasing the amount of power generated. But if the voltage becomes too high or too low, the efficiency of the inverter falls and it produces less power.
Rated Operating Voltage:
Each solar inverters has its rated operating voltage, and at around the rated voltage for the DC string voltage, efficiency is the best. For example, for a single-phase 220V output inverter, the rated input voltage is 360 V; for a three-phase 380V output inverter, the rated input voltage is 650 V. If the voltage of the string is much lower or higher than the rated voltage of the inverter, efficiency is reduced.
Voltage range and module configuration:
In sum, the conditions regarding the module configuration and string voltage are relevant to the generation of power. If the latter has a high enough string voltage, it means the inverter's maximum input voltage will already be exceeded, in which case an inverter fails or breaks down. Other inverter models allow a maximum input voltage of 1100VDC. That opens up a few options when designing but is very problematic to surpass such a voltage range.
It doesn't mean that the higher the voltage, the more power it will generate, even though higher DC string voltage sometimes provides better efficiency to an inverter. That means DC string voltage operates within the MPPT operating voltage of an inverter and as close to the rated operating voltage as possible. Besides, module configuration, installation condition, and maintenance will affect the power generation. Therefore, it should be taken into consideration during designing the solar system to ensure the efficient operation of the system.
