Did i fry my Victron MPPT 😮‍💨…

[Cat-Sam]

I have a 2 x 120w install on my RV, 4mm cables and wired to a Victron MPPT 100 / 50. I wanted to upgrade the system and learning that my limitation seemed to be the factory installed 6g (4mm) cables i realised that if adding any additional panels that i would need to do so in series (like the existing 2 already installed. Added 2 more panels of 100w each today, all connected up and checked, seemed OK. Took the RV out of the barn to check that i was harvesting some watts and checked on the Victron app and immediately got an over voltage warning (it was running at 118v), drove the RV back in so they system ran for max 3mins. After that i disconnected everything just to make sure, then next step check on here with someone that has more PV knowledge than me (not hard..).

The 120w panels are rated at 20.5v and the 100w panels are rated at 20.4v so I’m a bit lost as to why they output over the max 110v of the MPPT ? It was cold today, around 5 degrees C.

I‘m assuming i fried the MPPT but will anything else likely be damaged ? Then i assume i need to upgrade the MPPT to a larger unit, any advice ? A straight swap out would be the Victron 150/35 i assume.

Many thanks and happy sun harvesting

 

[42OhmsPA]

The 120w panels are rated at 20.5v and the 100w panels are rated at 20.4v so I’m a bit lost as to why they output over the max 110v of the MPPT ? It was cold today, around 5 degrees C.

Your answer is more than likely in what you wrote. Voltage goes up as temp drops.

This thread has lots of good info.

Cold weather and Voc?

Is there an actual formula? I am running an experiment and have 4x180w panels currently in 4s. I have seen 82v so far. Temps 50 to 70. Tomorrow morning in the upper 30's. my panels are 21.6 plus or minus .5% My controller is 100/50 Could not find anything to show. Only cold weather blanket...

diysolarforum.com

Also are you referring to Voc or VMPP with your numbers above?
I'd expect your Voc to be ~26V for those size panels.

I'd try rewiring to 2S and see if you let out the magic smoke.

The 150 would work but if you see yourself continuing to expand the system the 250 might be better.

Welcome to the forum.

 

[Samsonite801]

Here's a calculator (at bottom of article) which I like to use a lot:

Solar panel maximum voltage calculator - How to work out the max voltage

To get the maximum solar panel voltage you should expect from your solar panel, use our solar panel maximum voltage calculator.

gold-coast-solar-power-solutions.com.au

Victron has a calculator on their website as well.

 

[upnorthandpersonal]

The 120w panels are rated at 20.5v and the 100w panels are rated at 20.4v

What is the Voc on those panels?

 

[Cat-Sam]

Your answer is more than likely in what you wrote. Voltage goes up as temp drops.

This thread has lots of good info.

Cold weather and Voc?

Is there an actual formula? I am running an experiment and have 4x180w panels currently in 4s. I have seen 82v so far. Temps 50 to 70. Tomorrow morning in the upper 30's. my panels are 21.6 plus or minus .5% My controller is 100/50 Could not find anything to show. Only cold weather blanket...

diysolarforum.com

Also are you referring to Voc or VMPP with your numbers above?
I'd expect your Voc to be ~26V for those size panels.

I'd try rewiring to 2S and see if you let out the magic smoke.

The 150 would work but if you see yourself continuing to expand the system the 250 might be better.

Welcome to the forum.

Thank you so much and thanks for the welcome

2 panels are Voc 25V and 2 are Voc 26V, seems i picked a bad or good day depending on how you look at it…

Yes I’ll rewire back to the original set up and see what happens

I assume the Victron MPPT‘s are not fused