Mppt gets hot

DIY
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1

Hello. The mppt gets quite hot. Is it common to use a ventilator? Or is there nothing to worry about? Thanks in advance

2

Yes, its normal for the MPPT to get hot, and generally nothing to worry about. A cooler unit will theoretically last longer, but they are designed to have a long life even when run hot.

There are a couple of mitigation systems already built in;

  • There is a huge heat sink (basically the whole bottom of the unit), so if you mount it the right way, convection of air will help move that heat away from the heat sink
  • The mppt will derate (temporarily lower the Max charge current) when it gets too hot

There are a couple of options you have too;

  • Some users have added always-on fans or temperature controlled fans to move more air past the heat sink which can have a significant effect on the running temperature.
  • You can “turn down” the max current which in turn keeps the unit cooler. In VictronConnect, go to the gear wheel (Settings), Battery, look for “Max charge current”. This will default to the units design max (e.g. 20A for a 100/20) but can be set as low as you want.
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3

Thank you for your response! Very helpfull :slight_smile:

4

One last note about manually derating the controllers;

If you derate a 100A controller to 70A, you are not losing 30% of your production, you are losing 30% of your production during the period of the day when the controller would otherwise hit 100A which for most people is NEVER, and for some people is VERY SELDOM, and for others it is probably NOT WORTH CALCULATING.

Its important to realise this, and realise that in an off-grid setting, you will almost never be punished for derating a controller.
Consider the day when you need every drop of power - an overcast day or a raining day, where you need to make your daily quota (the amount of power you use per day) otherwise your battery will be starting each subsequent day lower than the day before, until you crash (or have to use a generator).
Lets say your daily usage is 10kwh. Your array is probably 10kwp, so on a good day you make 60kwh, on an overcast day you make 20kwh, and on a rainy day you only make 10kwh.
On a rainy day, your current will be so low that you won’t be anywhere near 100A - probably peaking at 30A if you are lucky.
On a great day, you will hit 100A, but you will have already filled your battery by about 10am, so throttling back to 70A, and therefore not being full until 10:30 makes no difference.