Auto-stringing is the automatic assignment of solar panels to inverter strings and MPPT inputs. This guide covers what it is, how string sizing and MPPT matching work under AS/NZS 5033, the mistakes to avoid, and how Solar Proof produces a valid configuration in seconds.
The short version
Auto-stringing assigns panels to strings and MPPTs so the array stays inside the inverter's voltage and current limits across temperature extremes. Done by hand it's fiddly and error-prone; done automatically it's fast and consistent, but still worth a designer's review.
What is auto-stringing?
A solar inverter has one or more MPPT (Maximum Power Point Tracking) inputs, and each accepts one or more strings of panels wired in series. Auto-stringing is software working out, automatically, how many panels belong in each string and which MPPT each string connects to, while keeping every string inside the inverter's allowed voltage and current range.
Why string sizing matters
Panel voltage changes with temperature, rising as it gets colder and falling as it gets hotter. String sizing has to account for both extremes:
- Too many panels in a string and the open-circuit voltage on a cold morning can exceed the inverter's maximum, risking shutdown or damage.
- Too few panels and the operating voltage on a hot afternoon can drop below the MPPT window, costing production.
- Unbalanced strings on one MPPT can drag down performance, so strings on a shared MPPT usually need matching lengths.
The Australian rules
In Australia, AS/NZS 5033 governs PV array installation, including how maximum array voltage is calculated using the lowest expected cell temperature for the site. A compliant design has to satisfy both the standard and the inverter manufacturer's stated voltage window. This is exactly the kind of calculation that's easy to get subtly wrong by hand.
How Solar Proof automates it
Pick your panel & inverter from the product library.
Lay out the array on the roof in the designer.
Auto-stringing runs, assigning panels to strings and MPPTs within the voltage window.
Review & adjust if needed, then carry it through to the SLD.
Common mistake: trusting any auto-stringer blindly. It gives you a valid starting point fast, but always sanity-check against the specific inverter datasheet and site temperature extremes before installing.
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Frequently asked questions
What is auto-stringing in solar design?
It's the automatic assignment of panels to inverter strings and MPPT inputs. Software works out how many panels go in each string and which MPPT they connect to, keeping the design within the inverter's voltage and current limits.
Why does string sizing matter?
It keeps the array within the inverter's MPPT voltage window across temperature extremes, too few panels and voltage drops too low on hot days; too many and it exceeds the maximum on cold mornings.
What rules govern string sizing in Australia?
AS/NZS 5033 sets the requirements, including calculating maximum voltage from the lowest expected temperature. The design must satisfy both the standard and the inverter's voltage window.
Does auto-stringing remove the need to check the design?
No. It gives a valid starting configuration fast, but a competent designer should still review it against the inverter datasheet and site conditions.
