Microinverters Vs. String Inverters
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Solar inverters have a great impact on the yield of electricity. Your choice between a microinverter and a string inverter impacts your system’s performance. But choosing between both kinds can be challenging. In this article, I have shared some tips on how to make this decision.
For domestic purposes, string inverters are preferred over microinverters. But in commercial systems, microinverters are more useful. However, the choice depends on certain factors but let’s first understand the basic differences between microinverters and string inverters.
String Inverters
Most residential solar power systems use string inverters as they are cheaper and easier to maintain. With one string inverter, a series of solar panels are connected. Only one string inverter is responsible for the power management of all the connected solar panels.
Connection Between String Inverter and Solar Panels
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As one inverter is connected to a string of solar panels, it is called a string inverter. This connection of solar panels can be either in series, parallel, or a combination of series and parallel to acquire a compatible voltage range. Generally, residential string inverters operate at 300-600 volts, whereas, in commercial systems, string inverters operate at up to 1500 volts. This range of voltages is also a risk.
String inverters are suitable for areas where all the solar panels are properly exposed to sunlight. If one of the panels is in a shaded region, it may affect the overall power output, as most panels are connected in series. So, string inverters do not yield well if one of the solar panels is not performing well. However, with DC optimizers, this problem can be dealt to some extent.
Microinverters
Microinverters are more common in commercial applications as they are more expensive and require more maintenance. They are dedicated inverters for each solar panel. Suppose a system has 20 solar panels installed, each connected to a microinverter. The output of all microinverters is then combined and utilized. Which also makes it easier to monitor the performance of every solar panel.
Connection Between Microinverters And Solar Panels
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Since every panel has a dedicated microinverter, if one of the solar panels stops working due to shade, it does not affect the performance of other panels. This makes microinverters suitable for regions that are often exposed to shade. Moreover, as each microinverter is connected to just one panel, the microinverter operates at low voltages, which is safer.
Besides, if you ever plan to expand the system, all you have to do is install one microinverters with every new panel. So microinverters also add the flexibility of expanding existing systems.
Since microinverters convert DC power to AC on the spot, microinverter-based solar power systems are slightly more efficient. However, efficiency comes at a price, several inverters have to manage, and the installation cost is also higher.
Now that you know both solar inverters have benefits and drawbacks, let’s discuss which is more suitable for you.
String Inverters Vs. Microinverters
Even though the function of both inverters is the same, converting DC power into AC power but both inverters have differences. You need to consider the following factors when making a decision.
● Efficiency
● Cost
● Viability
● Ease of maintenance
● Scalability
● System life
Now let’s discuss how and why these factors vary in both cases.
Efficiency
Generally, microinverters are 2-3% more efficient than string inverters. As they convert the power on the spot, power losses are low. Moreover, each inverter has to deal with less load, making it more efficient. However, given the cost of microinverters, adding one more solar panel to the system makes string inverters equally efficient at a lower cost.
Cost
String inverters cost less than microinverters. One string inverter of 20KW costs less than 20 microinverters of 1KW each. Besides that, the installation of one string inverter is also lesser than the installation of 20 microinverters.
Viability
For systems that are partially exposed to shading do not perform well with string inverters. Microinverters are more suitable for such systems. However, string inverters can be used if the solar panels are installed at height and there is no shading problem.
Ease of Maintenance
Taking care of one string inverter is far easier than 20 microinverters. However, maintenance is feasible in commercial solar power systems, and microinverters are more suited. Microinverters enable the monitoring of each solar panel, and if one of the panels is not performing well, it can be easily detected.
Maintaining multiple inverters for domestic consumers is not feasible regularly, so string inverters are more suited.
Scalability
Once a string inverter of 20KW is installed and solar panels of the same capacity are installed, the same inverter cannot be connected to more panels. If the consumer plans to expand the system, another string inverter has to be installed.
However, in the case of microinverters, as one dedicated inverter is installed with each panel, more sets of panels and inverters can be connected to the same system.
System Life
Microinverters serve for a longer period compared to string inverters. This is why microinverters typically have a warranty period of 25 years. Whereas string inverters have a warranty period of 8-12 years.
| Microinverter | String Inverter |
| 2-3% higher efficiency | Slightly lower efficiency |
| Suitable for systems exposed to partial shading | Suitable for systems that are never exposed to partial shading |
| Expensive | Cost-effective |
| Enables monitoring of each panel | Provides stats of overall system |
| Safer as input voltages are low | Input voltages are higher which can be risky |
| Up to 25-year warranty
|
8-12 year warranty |
Table: String Inverter Vs. Microinverter
Final Thoughts
Given all the above factors, string inverters are cost-effective and also provide almost the same output. However, if your panels are exposed to frequent partial shading, microinverters can serve better than string inverters.