I have a 100/30 mppt and I’ve over panelled it with 1200watts of solar on 24v system.
It’s on the flat on a motorhome roof and it’s working well but seems to average 25amps in full sun in the middle of the day. It can sometimes hit 30amps for brief moments.
Is this the most I can expect from 1200w panels on the flat or is the 100/30 limiting them below the 30amps claimed?
In optimal conditions the MPPT 100/30 has no problem providing 30A. Check the manual for possible reasons it underperforms. Also most panels derate quite a bit when they get warm.
That’s good to know the mppt easily puts out 30amps. I suppose it must be the heat limiting the system then. It is about 28c today. From 11am they have hovered around 24amps till 4 or 5. . I’ll read through the manual too.
Also check if the MPPT is hot, above 40 degrees C it derates.
It does get fairly hot but not crazy hot.
This is the output, misty morning but then full sun all day. The graph looks flat for the mid part of the day, is that normal or does it look like it’s being limited? I’ve got nothing to reference it to because my last controller wasn’t a victron.
The critical question is what is the output voltage of the controller when it is running at 25A compared to the absorption voltage in the settings. If it is under absorption voltage then the MPPT is limiting, if it is at absorption voltage then the battery or MPPT to battery cabling is limiting. Show us a screenshot of the status page when this is first happening during the day and you battery settings.
Does this help? These are all from today, full sun after morning mist cleared, batteries at 38% victron lfp 200ah # 24v reached 100% by the evining but didn’t reach float.
That definitely confirms that it is not the battery or battery cable limiting the power. It is therefore either the mppt throttling back due to temperature as discussed above or some issue with the panels or panel cabling. See if you can blow air over the MPPT to cool it down.
Thank you. The panel wiring is four mm2 and about 12m run. I wanted to swap it to 6 but when I upgraded the panels but it’s a big Job to re run it.
I’ll try to get a fan on it when I can. I was also thinking of fixing it to some bits of aluminium extrusion as well to act as an extra heat sink. I’ll report back my findings.
Your input voltage to the MPPT in showing as 30V in your first screenshot, so at 600W into the battery that is 20A. For full output it would be 25A. A voltage drop calculator give the voltage drop as 3V, which is higher than desirable but with 1200W available should not be limiting.
How does the 30V compare to the panel spec for max power and open circuit voltage (Vmp and Voc).
Do you have your panels in parallel, could you try them connected in series, higher voltage, lower current.
