question

friaras avatar image
friaras asked

Does the MPPT 150/35 Controller have Over Voltage protection if the Max input is over 150?

Hello, I have a Victron 150/35 MPPT controller, and 7 x 100 Watts panels in series, the panels OCV is 21.6v The Victron app shows at peak hour a max of 135 volts input since is a 150v max can I add another 100 watts panel same as the other 7 and will it exceed the max, will the controller shut down if it does?

Here is a basic description of the system.

7 x 100 Watts HQST-100D-SS (older model) newer model have a few different specs.

12/2 x 25' of marine wire from panels to MPPT.

Victron 150/35 with BT adapter.

5kW LiOn battery at 36v

Would like to add another same model as the other 7. Will it be better/safer to change configuration to 2 parallel strands of 4 panels each? Thanks in advance.


MPPT Controllers
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4 Answers
Elimac avatar image
Elimac answered ·

You are already on the limit with your current 7 panels, as far I'm concerned. Remember that the peak voltage can go higher in lower temperatures. And in top of that, if it happens when the battery is full or low consumption... you can easily go near 150V in the future, even with those 7 panels.

In my opinion, yes, if you want to add an 8th panel, you should make two strings of 4 to be safe. And in this case you have margin to make 2x strings of up to 6 panels (12 in total), if you have the space.

No, as far as I know, the MPPT does not shut down. You can just burn the input stage.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @friaras@gmail.com,

Exceeding the maximum PV input voltage rating will destroy the MPPT.

It is also important to be aware of the role that temperature plays with panel voltage. Increasing voltage, as temperature decreases. So even if a system appears to work for some time, if you are too close to the limit it can appear to be working and then, the conditions for a particular day can destroy the MPPT.

There is a MPPT sizing calculator here that will estimate the maximum voltage of your PV array, taking temperature and panel characteristics into account.

https://www.victronenergy.com/mppt-calculator

Note the general advice for a safe maximum number of cells for the 150V unit is 216 (6 x 36 cell 12V panel in series). This is documented on page 6 of the manual.

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adev avatar image
adev answered ·

As others have said, changing the configuration to 2 strings in series of 4 panels in parallel (or indeed 2 strings parallel of 4 panels in series) is the way to go. This will bring both the current and voltage to levels well within the range of that controller’s specifications.

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lega4 avatar image
lega4 answered ·

I've just tried with my 100/30 controller to connect 5 panels (19V) in series and actually the Victron App directly told me "input voltage exceeded". So at least to some extend there is a protection here and you will not "burn" the controller when connecting more volts than needed. Of course this might not work if you exceed it too much, but I think you should be fine trying out.


And of course, I also agree with others saying it's better to make a parallel connection of a series to balance voltage vs amperage.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

I've just tried with my 100/30 controller to connect 5 panels (19V) in series and actually the Victron App directly told me "input voltage exceeded".

Do not confuse an overvoltage alert, with an overvoltage protection.

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kevgermany avatar image kevgermany ♦♦ commented ·
You are very lucky that you're not buying a new controller.

There are other posts here saying there is a small tolerance for over voltage, but the real answer is to prevent it from happening. I.e. correct design and installation. @klim8skeptic is perfectly correct.


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