Quick definition
A string inverter is the classic, straightforward approach to solar inverter architecture: multiple panels get wired together in series into one string, that string's combined DC output travels to a single central inverter, and that one inverter converts everything to AC power at once. It's mounted separately from the panels, typically at ground level near the utility meter or in a garage, rather than distributed across the roof.
This is the simplest, most established inverter architecture, and remains a genuinely practical choice for many installations, particularly roofs without significant shading challenges.
At a glance: string inverters generally cost less upfront than microinverter systems, since only one central unit is needed rather than one device per panel, making them a common default choice for straightforward, unshaded installations.
Why it matters
For a roof without significant shading concerns, a string inverter often represents the most cost-effective, straightforward path to a solar installation. Fewer individual components, easier access for maintenance at a single ground-level or garage-mounted location, and lower total equipment cost make it a genuinely practical default choice for many homes. That single unit will likely need replacing once during the system's life: a Bern University of Applied Sciences survey of more than 2,100 residential inverters found that over 65% had no yield-relevant fault through their 15th year, though the researchers noted the devices studied skew older than today's market.
The tradeoff is real, though: because all panels in a string share the same current, a single shaded panel can meaningfully limit the entire string's output, dragging down every panel wired into it, not just the shaded one. The string mismatch loss calculator puts a number on how much a weak panel costs the rest of its string. This is exactly why roofs with meaningful shading challenges more often move toward microinverters or power optimizers, architectures specifically designed to prevent one panel's reduced performance from affecting its neighbors.
Understanding string inverter architecture also helps explain some practical system realities, like why installers sometimes split an array across multiple strings tied to separate MPPT inputs on the same inverter. Different roof sections with different orientations or shading conditions often perform best when managed as genuinely separate strings, each independently tracked, rather than forcing every panel into one combined string regardless of its specific local conditions. It also puts real weight on that one central unit: NREL research on inverter reliability notes that the inverter subsystem receives the largest share of service calls for operation and maintenance in a PV system, which is why the equipment's warranty terms and accessibility deserve attention up front.
Where you'll see this
The central inverter vs string inverter cost tool compares string inverter architecture against a central inverter approach for larger installations.
If you're weighing whether shading conditions justify a different architecture, the microinverter vs string inverter output tool compares expected output for your specific roof.
This term comes up in nearly every residential solar system design conversation, in inverter equipment spec sheets, and any comparison between the major inverter architecture choices available for a new installation. The Department of Energy's page on inverters and grid services explains the different inverter designs, including string inverters.
Frequently asked
Generally yes, since a string inverter system only requires one central unit rather than a separate inverter or optimizer for each panel. For roofs without significant shading challenges, this cost advantage often makes a string inverter the more economical choice.
Not as well. Since panels in a string inverter system share current, a shaded panel can drag down the output of the entire string it's wired into, a limitation microinverters and power optimizers are specifically designed to address.
This depends on the specific inverter model and how many independent MPPT inputs it has, commonly one to four or more, each capable of managing a separate string with its own optimal operating point.
Generally easier for repairs, since there's just one central unit to access, typically mounted at ground level or in a garage, rather than many individual units scattered across the roof. If the single string inverter fails, though, it can affect the entire connected string at once.