This note has no answer, and that is the useful part. Stop looking through the manual for a number that is not in it.
The SPF series manual covers wire gauge and terminal type. It does not give a torque specification for the battery terminal studs. Several installers have reported asking Growatt support directly and receiving no figure.
Why an undocumented torque spec matters
A loose DC lug on a 48 V battery connection is one of the more dangerous faults in an off-grid system. Resistance at the joint turns into heat, heat increases resistance, and the joint runs away from you. It is a recognised cause of fires in battery installations, and it is entirely preventable with a torque wrench and a number.
Overtightening is a real failure too. It deforms the stud or crushes the lug, which produces the same poor contact you were trying to avoid.
What people do instead
The common workaround is to use the torque rating for the stud size and connector type from the connector manufacturer rather than from Growatt. For the M6 studs on these units that generally lands in the region of 15 to 20 inch pounds.
Be clear about what that figure is. It comes from the hardware maker, it is not a Growatt specification, and it does not carry Growatt’s endorsement. This site will not present it as one.
What would close this
Any of three things. A Growatt document that states the figure. A written reply from Growatt support quoting it. Or a labelled torque marking on the unit itself, which some revisions carry near the terminal block.
If you have any of those, send it to info@solarspecdb.com with the model and revision, and this note gets replaced by a cited answer.
Meanwhile
Check the joint rather than trusting it. After the first week of operation, and then seasonally, feel the lug and the cable near it during a heavy charge or discharge. A joint that is measurably warmer than the cable running into it is telling you something. A thermal camera or an infrared thermometer makes this obvious in seconds and is worth owning if you run a system like this.
Status: unresolved. Recorded deliberately rather than filled with a guess. The 15 to 20 inch pound figure above is attributed to connector hardware ratings and is not a Growatt specification.