Hello. I am planning of connecting multiple solar panels in series, which will amount to ~226 volts. The MPPT can only handle 250 volts. My question is, what can I use to limit the solar input voltage, so it does not go above 250 volts on cold winter days?

I found this circuit breaker on amazon, I am wondering if this would work for my needs.

Quote

2P 250V Circuit Breaker Distribution and Control Devices Circuit Breaker Low Voltage DC Circuit Breaker (40A)

https://www.amazon.de/-/en/Circuit-Breaker-Distribution-Control-Devices/dp/B09XVN4FGP/

 

Speaking of my solar panels, I will be connected 7 solar panels in series, each 32.4v and 12.4Amps. I really don't want to connect less than 7 solar panels, just because I need that additional solar power. Thanks.

13 minutes ago, NoahAndArk said:

Speaking of my solar panels, I will be connected 7 solar panels in series, each 32.4v

You would have to look at the Voc for your panels and look at the temperature co-efficient formula and based on your expected minimum temperature, calculate out what the Voc of your panels could come up to, to determine whether you will be exceeding the MPPT's max Voltage... the Circuit breaker would trip if you exceeded the current, 40A, for some time, this would not and could not prevent a higher voltage from reaching your MPPT.

Hello. Thanks for this valuable information. Turns out, according to a calculator, I can only connect 5 solar panels in series. Would you mind taking a look at the specifications of the solar panel, it is the 440T model?

https://static.csisolar.com/wp-content/uploads/2022/09/09154049/CS-Datasheet-TOPHiKu6-TOPCon_CS6R-T_v1.7_EN.pdf

 

Your panel's VOC = 39,4V at 25°C
It then states a deviation of 0,25%/°C
39,4V X 0,25% = 0,0985V/°C
Let's assume a winter panel temp at 0°C and clear skies with full sun at a perfectly angled and clean panel.
That means 25 X 0,0985V = 2,4625V increase, i.e. your panel would have a VOC of 39,4V + 2,5V = 41,9V
With 6 panels that would be 251,4 , i.e. just above your MPPT limit.  This of course assumes that your panels are at the ideal angle for the winter months and that you would have 1000 W/m² at 25°C , which I doubt you will have.
So yes, 5 panels will be on the safe conservative side. 

Edited December 31, 20241 yr by zsde

5 hours ago, NoahAndArk said:

Hello. Thanks for this valuable information. Turns out, according to a calculator, I can only connect 5 solar panels in series. Would you mind taking a look at the specifications of the solar panel, it is the 440T model?

@zsde did the calculations for you. 6 panels, if 250V is your Voc limit, would probably be too much, but you did not specify where you are located, or what your minimum expected temperatures are, here I can expect maybe -6degC on a really crappy cold winter morning, but right now, 46.5degC in the shade, we have more a high temperature rather a low temperature problem. Last winter, I think the lowest I saw, was -2degC, and that was briefly before we headed towards our 20-odd peak for the day.

Also what inverter or MPPT charge controller have you got, how much power can it handle and how much current, assuming it only has single PV input. Maybe 4S2P with 8 panels in total may be doable and give you more potential power that way around...