I’m experimenting for the first time with solar and I have a SmartSolar MPPT 100/30 being fed by a single Renogy 24V 200W panel. I’m planning on adding two further panels, but I have a concern. The Victron app is showing me that the current panel produces approximately 30-32V, with occasional values of up to 34.56V. I’m assuming that this means with 3 panels in series, there is the potential for an input voltage to the charge controller of 103.68V. This is above the 100V max for the controller, but can the controller cope with this? I know I could connect in parallel, but I was hoping that I might get to 6 panels at some point (3 in series linked in parallel with another 3 in series). I guess the question is: How robust/tolerant is the MPPT 100/30?
Thanks.
There is 0 Tolerance. It is a absolut-maximum-do-not-exceed-rating (Including Voc, not only Vmppt). Also mind that voltage of solar will increase with temperature falling. Usual rating is about -0.5% per °C, so at -10° (assuming you have 20° now) you’ll see about 15% higher voltage.
(For the exact rating, check the panels datasheet)
Thanks for such a quick (and definitive) response 
Obviously, it’s not what I was hoping for, but at least I know what the situation is.
This must be quite a common issue. Is there a generally accepted and/or easy way to limit the voltage into the controller to avoid any potential damage?
If not, I’ll just have to restrict my plans to 2 panels in series in parallel with another 2 in series.
Yeah, it is recommended to leave a nice headroom there. Sometimes also the panels voltage may be a bit above it’s rating, having 3 in series may even (worst case) have 3times a +X manufacturing tolerance.
Different panels have different voltage / current combinations. So the MPPT has some headroom on either rating to allow different panels to be connected. But you don’t have to max-out on both (voltage and current) to reach the mppts maximum capability.
For instance the MPPT 100/30 has limits of 100V and 35A, which would be 3500W and by far exceeding the maximum of 880W. (Charging 30A at 29.3V)
So, to reach a 880W Input to saturate the MPPT a PV-Array doing 50V and 16A would be sufficient, without coming close to any of the maximum input-ratings.
(Quick maths, hope did it right)
That’s great information. Thanks. 
To connect 6 panels, you could - depending on current - eventually do 2 series, 3 parallel.
However, more than 2 parallel strings requires more detailed review of the specs, as every string needs to be able to withstand a “reverse-current” equaling the sum of the two other strings.
If they don’t support that, you’ll need to add string-fuses to ensure reverse-current occurring won’t damage panels and/or leading to a fire.
But 6 panels is highly overcomissioning a 100/30 most likely. You’d better get a second mppt there to also be able to utilize that power during peak times.
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