Properties of Solar Micro Inverters

Engr. Dr. Muhammad Nawaz Iqbal

An inverter made specifically to work with a single PV module is known as a solar micro-inverter. Each panel’s output of direct current is changed into alternating current by the micro-inverter. Its layout enables the modular parallel connecting of numerous independent modules. Compared to normal inverters, microinverters provide a number of benefits. The key benefit is that they electrically isolate the panels from one another, so that even a full module failure or minor quantities of shade, debris, or snow lines on one solar module do not significantly diminish the output of the entire array. Each microinverter tracks the maximum power point for the connected module to capture the most energy. With the introduction of the microinverter solution, additional safety, lower amperage cables, easier stock management, and simpler system design are further aspects.

Since each inverter must be put next to a panel, one of the main drawbacks of a microinverter is that it has a greater initial equipment cost per peak watt than a central inverter of similar power (usually on a roof). Due of this, they are also more difficult to maintain and expensive to take apart and replace. Some manufacturers have developed panels with integrated microinverters to overcome these problems. A central inverter, which will need to be replaced during the life of the solar panels, often has a shorter lifespan than a microinverter. As a result, a short-term financial disadvantage may eventually turn into a benefit.

Direct current is generated by solar panels at a voltage that varies depending on the lighting and module configuration. Modern modules with 6-inch cells typically have 60 cells and generate 24–30 V nominally. (Therefore, inverters are prepared for 24-50 V. A panel’s output efficiency is also significantly impacted by the load the inverter applies to it. Maximum power point tracking is a method that inverters employ to assure optimal energy harvest by changing the applied load. The proper load that the MPPT system should apply, however, is affected by the same problems that result in output varying from panel to panel. A string inverter only notices the total change if a single panel operates at a different point and adjusts the MPPT point to match. This causes losses for all the panels, not just the darkened panel. In some cases, shading of as low as 9% of an array’s surface might result in a 54% reduction in system power. However, as was already said, these annual yield losses are only modest, and string inverters equipped with modern technology can greatly lessen the effects of partial shadowing.

The location of the device and the requirements for heat dissipation are two additional difficulties with centralized inverters. Usually, large central inverters are actively cooled. Location of the inverter in relation to workplaces and occupied areas must be taken into consideration because cooling fans produce noise. Additionally, because cooling fans contain moving parts, contaminants like moisture, dust, and dirt over time may degrade their performance. Although quieter, string inverters can make a humming sound in the late afternoon when inverter power is low. It is possible to isolate and fine-tune the output of a single panel using a microinverter that is connected to it. Any underperforming panel has no impact on the panels nearby. In that scenario, the overall output of the array is up to 5% more powerful than it would be with a string inverter. These benefits can become significant when shadowing is taken into account, if it is, with manufacturers typically claiming 5% better production at the very least and up to 25% better in some situations. In addition, a single model can be applied to a wide range of panels, and additional panels can be added to an array at any moment without having to match the existing panels’ rating.