Solar Panel System GuideEvery grid-tied solar array needs to turn the direct current its panels produce into the alternating current a house runs on. That job belongs to the inverter. The two main approaches, a central string inverter and per-panel microinverters, behave very differently once part of the roof falls into shade. Facts here come from EnergySage and from the Enphase IQ8 datasheet.
What the inverter does
The Department of Energy describes the first half of the process at the panel. When the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells, and this energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.
That flow leaves the panel as direct current. The Department of Energy notes that solar photovoltaic modules are where the electricity gets generated, but are only one of the many parts in a complete PV system. The inverter is the part that converts the panel's DC output into the AC power a home and the grid actually use.
How that conversion is arranged, at the string or at each panel, is the design choice that shapes real-world output.
String inverters and the weakest-panel effect
EnergySage describes a string inverter setup as one where an installer arranges the solar panels into groups connected by wires referred to as a string. Multiple strings of panels are then connected to a single inverter, which is called a centralized inverter.
That shared wiring has a catch under shade. EnergySage states that every panel connected to a string is limited to the output of the weakest panel. So a single shaded or soiled panel can pull down the whole string's production.
The monitoring picture is coarser too. EnergySage notes that string inverters can only optimize power output at the string level, not at the individual panel level, and that they only offer string-level monitoring.
Microinverters and per-panel behavior
Microinverters take a different approach. EnergySage notes that microinverters are connected to each individual panel, usually mounted onto the back of the solar panel, though they can also be placed next to the panel on the racking system.
Because each panel has its own inverter, the power output of each panel is optimized independently. That is why a shaded panel does not cap its neighbors, and why microinverters allow you to monitor the performance of individual solar panels rather than only the whole string.
Enphase publishes hardware numbers for its IQ8 microinverters that show the scale of these units. Across the IQ8 family, peak output power runs from 245 to 384 VA per unit, with peak efficiency of 97.4 to 97.6 percent. Enphase also states the IQ8 series can produce power even when the grid is down, when paired with the required Enphase system controller.