A string inverter is a type of inverter which is connected to a string of solar panels. The term ‘string inverters’ refers to ‘central inverters’ as well. It is used in solar photovoltaic applications. A string of solar panels is also called a solar array.
During the inverter’s operation, the DC power received from each solar panel is combined and, at the same time, converted into AC power. The number of solar panels that can be connected to a string inverter is determined by the string inverter’s input voltage rating.
These inverters have been around for decades, are relatively affordable, and meet the needs of most small-scale solar installations.
It is recommended that string inverters be installed on roofs that have a uniform southern exposure without any shading problems. A shaded panel limits the energy production of the entire string because the output of the worst-performing panel determines the output of the entire string.
Consider the case of a large pine tree that covers one or two of your solar panels in the noon. Considering that all the panels are connected in a string, if these one or two modules are shaded, then the output of all the other panels will be adversely affected.
The use of string inverters with solar PV systems has several advantages and disadvantages. Our objective here is to provide you with information regarding string inverters.
Advantages and Disadvantages of String Inverter
Advantages of string inverters
A string inverter has several distinct advantages over other types of inverters. The following are a few of them to consider:
1. String inverters are typically mounted on walls in a common room. Therefore, troubleshooting does not require frequent trips to the field, which facilitates ease of maintenance. It is of great benefit in places that experience extreme cold or heat.
2. The use of string inverters has been around for decades, as mentioned earlier. Due to this, most string inverters are reliable, and electricians are familiar with this technology.
3. In terms of costs, string inverters are currently more affordable than microinverters. Microinverters require one inverter per panel, whereas string inverters only require one inverter per installation.
Disadvantages of string inverters
The following is a list of string inverter disadvantages/drawbacks to consider.
1. An inverter failure will render the entire solar array unusable. There could be a substantial loss in electricity production as a result of this event.
2. When a string of solar panels is connected to the string inverter, the performance of each panel is equal to the performance of the worst-performing panel. Due to this, if one panel is obstructed by dirt or shade, every other panel attached to that inverter will produce at a reduced capacity.
3. There is no way to expand the capacity of a string inverter in the future unless you purchase one that is oversized since once an inverter has been installed for a specific rating, the rating of the inverter cannot be changed. It would be necessary to purchase an additional inverter in this scenario.
4. The roof of your building is also constantly exposed to high-voltage electricity. Due to the fact that the energy is converted at the end of the row of panels and not at the panels themselves, high voltage (up to 1,000 volts) DC electricity is transferred across the roof. The risk of arc-faulting and fire can be seriously increased by this situation.
Final thoughts
Ideally, string inverters would be suitable for roofs with a uniform pitch and abundant southern exposure. Having been used for decades in the home solar industry, these panels are affordable and have proven to be durable and reliable.
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