In this blog, we will cover the common types of Grid-Tied or Grid Connected Solar Inverters used in roof-top Solar Power Plants, their Pros and Cons
Solar Power Plants that use only utility grid as a complementary source of power are called grid-tied or grid-connected systems. In a grid-tied system whenever there is a shortfall in power production from solar due to external conditions, the grid power will compensate the shortfall.Similarly, if the power production by a solar PV system installed in a facility, is more than that of the consumption in the facility, based on inverter setting the excess power is
- Either pumped back to the grid by the inverter as export
- Or the inverter will limit the power production from Solar PV so that there is no export of Power
Inverters are incredibly important pieces of equipment in a rooftop solar system. Depending upon few key functions like DC Power Extraction, Inversion of Power from DC to AC Inverters are classified into three types,
- String inverters
- Microinverters
- Power optimizers
- String Inverters
In a string inverter system, the DC Power Extraction Unit (MPPT) and the Inversion unit are bundled in a single box. In such systems solar modules are connected in series using DC cables to form DC strings of high DC voltage (up to 1000 V / 1500 V). The strings are then connected in parallel to the MPPT of the Inverter. In a string Inverter, a single MPPT typically manages a large number of modules.The life of a string inverter is typically between 7 to 10 years.
String Inverter pros:
- Standard inverter
- Cost is Comparatively low
- Performs well with no shade
String Inverter cons:
- No ability to monitor each panel individually
- Overall production decreases if one panel is damaged or shaded
- Not optimal if your solar panels are facing different ways
- Increasing power needs are more difficult and may require second central inverter installation
- Microinverters
Microinverters as the name indicate are miniaturized inverters. Microinverters are small units built into each individual solar panel that convert power. Enphase pioneered the Microinverters technology in 2006. In micro-inverter architecture each Solar Module is connected to one Microinverter. The micro-inverters are then connected in parallel to form AC branches.
Microinverter pros:
- Micro-inverters architecture is highly efficient, reliable and safe compared to traditional inverter architecture.
- The system can effectively handle any mismatch in solar power production among solar modules
- An inverter failure in a micro-inverter system only impacts that Inverter and module
- Increasing power needs are easier and less expensive than installing a second central inverter
- Good for rooftops where solar panels may face different directions
- Shade from any object won’t reduce the whole solar panel system power output
- Individual panel monitoring available ensuring ease in maintenance and warranty claims
Microinverter cons:
- Higher initial cost
- Not necessary if all panels face the same way and are not shaded
- ower Optimizers OR Optimized String Inverter System
We cannot speak of Power optimizers system without mentioning SolarEdge. SolarEdge established in 2006, pioneered the Optimizer Technology. Power optimizers are somewhere in between string inverters and micro-inverters both in how they function and in price. As with micro-inverters, power optimizers have a component (the “optimizer”) underneath and within each solar panel. But rather than change the DC to AC right there on site, these inverters optimize the current before sending it to one central inverter. This is more efficient than a string inverter, as any sluggish production from one panel doesn’t slow the whole system, but more cost-efficient than a standard micro-inverter setup.
Power optimizer pros:
- More efficient than string inverters
- Less expensive than micro-inverters
- Individual panel monitoring available
Power optimizer cons:
- Higher initial cost
- Not necessary if all panels face the same way and are not shaded