question

jakecloss avatar image
jakecloss asked

Panel wiring

Hello.

I'm trying to workout best way to wire up my panels I have a victron 150v 100a mppt Controller, my panel have a maximum voltage rating of 30.5v.

So sould my strings of panels strings in series be made up of 4 or 5 panels.

My system is 48v

I'm guessing that as my panels are used I could get away with 5.


4 panels 122v

5 panels 152.5v


Solar Panel Watts 255

Maximum Power Voltage - Vmpp(V)30.5

Maximum Power Current - Impp(A)8.37

Open Circuit Voltage - Voc(V)38.1

Short Circuit Current - Isc (A)8.83

Panel Efficiency (%)15.67

Height (mm)1640

Width (mm)992

Thickness (mm)40

Weight (KG)18.5

Cell TypePoly

wiring
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
viktor avatar image
viktor answered ·

Hello.

You can use the online Victron calculator for charge controllers:

https://www.victronenergy.com/solar-charge-controllers

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

viktor avatar image viktor commented ·

For calculation voltage of your system you must use open circuit voltage of solar panel Voc, and also you need to consider temperature coefficient of solar panel. But if you don't familiar with this calculation, just use Victron calculator:)

0 Likes 0 ·
Justin Cook avatar image
Justin Cook answered ·

@Jakecloss, given that the 150v input voltage limit on the MPPT 150/100 is a HARD limit, I strongly advise playing it safe. I realize that the panels are old, as you say, but we must always plan for worst-case scenario. Taking into consideration that your VOC (the most important measurement here, not the Vmpp) is 38.1, you should not connect more than 3 panels in series (114.3 VOC) to the MPPT to ensure that even in case of failure and the panels going open circuit, the voltage will not overload the controller.

Limit your series connections to strings of 3; the upside is that this gives you more panels to play with for parallel connection. You didn't list how many panels you have, but you can run quite a number of parallel strings of 3 in series with this controller.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.