Hello, Building out a solar system for our motorhome and Im looking at using the Victron MPPT 150/100 solar controller with six 200W solar panels. Panel configuration would be three parallel sets of two solar panels in series. This would push 73 volts and 19.2 amps into the controller (it accepts 150v and 100a). I thought that with these numbers coming in at less that half the controller’s capabilities, that I could later upgrade with additional solar panels if I chose to. However, my installer says my configuration maxes out this controller, and that I’d need another controller if I increased the system’s size. Can someone explain this for me? Thanks…
So, the controller can put out 100A, not accept 100A - that’s not strictly relevant here since you’re nowhere near its input current limit in any case, but it’s important to note in general. The second number in controller names is the maximum output current.
Assuming you’re charging a 12v Nominal battery bank, 1200w of solar input / average charging voltage output = 88A of charge current, meaning that adding more solar panels to the setup wouldn’t get you much. You could add another two panels if you wanted, but no point beyond that.
If you’re charging a different nominal voltage, like a 24vNom battery bank, that changes the math.
Victron’s MPPT Calculator can help you with the math on things to work out what kind of array and controller combinations would be best to achieve your desired results: https://mppt.victronenergy.com/
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The 150/100 is obese. You could fit 2x 100/50 in the same area. If you leave room for another 100/50 that will allow you to expand another 600w in the future.
The MC4 version is only 30A in. That might be the limitation. You might only be able to add more in series, which may not be the best for shading etc. If you partially shade one panel in series, the array performance drops significantly.
Personally, I would install smaller arrays and controllers vs one big one.
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Going to assume then you have a 12v system?
12v x 100A is 1200watts
You are installing 6 x200w - that is 1200w.
So technically, yes on paper you are near the max the controller can do.
PS there is some variation for example the battery does operate at 14 so 1400w is also possible.
And also rhe panels only produce 1200w in the perfect temperature and orientation conditions.
So you can add another string to maximise the chances of the full 100A output continually. (The spec sheet shows a max input current limit - it is not 100A)