Both topologies convert PV output from DC to AC. A string inverter serves one or more strings and may provide several MPPT inputs. A microinverter sits at module level and controls that module's operating point. See AC vs DC solar panels for the full energy path.
Compare the actual design
- String and MPPT allocation: identify every module on each string and tracker. Do not describe a multi-MPPT inverter as controlling the whole array at one operating point.
- Shade: trace when and where shade lands. Bypass paths, module layout and inverter controls affect the loss; a topology label cannot provide a reliable percentage.
- Electrical limits: verify cold open-circuit voltage, operating voltage, current, power and permitted string lengths using the exact documents.
- Monitoring: confirm whether module-, string- or system-level data is available to the installer and owner, and whether access depends on a gateway, account or subscription.
- Service boundary: record what stops when a device, branch, gateway or shared inverter fails, and what roof access a replacement requires.
Field decision
Module-level conversion may suit a layout with different operating conditions or a requirement for module-level visibility. A string inverter may suit a design that can be grouped cleanly across its available MPPT inputs and where accessible central service is valuable. Neither statement is a rule: product limits, network settings, rooftop conditions and the service model can change the result.
Before accepting either proposal
- Match the model numbers on the quote, datasheets and design.
- Mark roof faces, shade windows, strings, MPPTs and AC branches.
- Check operating limits and the intended export-control arrangement.
- Read the exact product and performance warranties, including labour, access and transport terms.
- Confirm how commissioning data and later diagnostics will be accessed.
- For an Australian SRES installation, confirm the exact models are on the approved product lists and installed before the relevant listing expiry.
Use the topology to ask better questions. Use the documented site design to make the decision.