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wolfandy avatar image

Would this panel setup risk damaging the 150/35 MPPT?

Hi all

would this panel setup pose a long-term risk on the 150/35? Voltage is still within limits, but Amps is higher. I understand that the MPPT would limit to 35A - but would running a higher current pose a risk of damaging the MPPT in the long-term?

solar.jpg

Thanks, wolfandy

MPPT - Solar Charge Controllermppt smart solar
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2 Answers
lehrling avatar image
lehrling answered ·

From the Blue Solar MPPT 100/35 manual:

1a) If more PV power is connected, the controller will limit input power.

From the VictronConnect manual:

Max charge current

Allows the user to set a lower maximum charge current.

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seb71 avatar image
seb71 answered ·

5 degrees C is minimum temperature you can have there?


Even so, 147.5V is quite close to the maximum limit (150V). I would be more worried about this.


What is the actual VOC of that PV panel?

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Yeah, I live in Cape Town and that's about as cold as it gets here in winter. And that's also night-time temp. During the day it is around 13-16 degrees (@13deg it would be 143.9V)

VOC of the panel is 46.2V


Ah. I think it's OK then.

When the Sun is high in the sky (summer), it will be also very hot.

Unfortunately your low temps are out of range..

You might want to re-work your Voc calculations..
cape-town-weather-stats.png

Thanks for the input :-)

If I take the Record-Low temp, then I would end up at 150.1V. If I take the Mean Min temp, I get 149.2V

But my question is how relevant these temps are in reality - because typically I would assume that the Low temps were recorded during night-time. The Daily Mean in the table is always at least 10deg higher than the Mean Min - which means that when the sun is out, the voltage should be below 150V. Plus in winter time we get significant more clouds, which means less solar irradiation (and hence also less V, or not?)

"But my question is how relevant these temps are in reality -"

I have done these sums endlessly... (really)

In the 10 years I was on grid, my array went overvoltage once that I noticed.

It should not have happened, I had 100 years of weather data,, and I have a good grasp of my panels temp coefficient. My installer was ok with the array Voc @ local temp data.

Voc @ local record lowest temperature should be reflected in calculations for proposed arrays.



Ok - thanks

At -1deg I would be at 150.1V and at 0deg at 149.7V. So extremely borderline...

So that means you would not recommend putting the panels in 3S? My idea was to try to extend my solar day by going 3S instead of 2S

You have done the sums... records are made to be broken... then smoke comes out of mppt's.

2 series looks logical for a 48v batt..

;-)

Thanks for your help :-)