Proper sizing of solar controller

[Mike Lewis]

I have three solar panels mounted flat on the roof of my trailer, totaling 355 watts of rated power. Before my next long trip I intend to buy a portable panel as well, which may be up to 100W. My total solar "capacity" would then be 455W, assuming I deploy the portable panel.

The datasheet for the Victron SmartSolar MPPT controllers says that their 100/30 controller is rated for nominal 12V PV power of 440W, and their 100/50 controller is rated for 700W. So my total planned solar panel capacity slightly exceeds the rating for the 100/30 controller. Do I need to get the 100/50 controller instead? I'm thinking that the angle of the sun will always keep the rooftop panels below capacity and the total below the 440W limit, but I'd like to hear other opinions.

[Jim Bennett]

Remeber you are quoting the maximum capacity, a point you are likely never to get near, and if you deploy the temporary panel it would likely be because your permanent setup is producing very little.

Minimally, you could monitor the current coming in from the panel to see if you are anywhere near maxing out, and if by chance you are getting close then you could get a larger controller.

[Tin]

Mike, you should be fine but if you want a little cushion try the SmartSolar MPPT 150/35
https://www.victronenergy.com/upload...-150-35-EN.pdf

[tdf-texas]

Originally Posted by Mike Lewis

I have three solar panels mounted flat on the roof of my trailer, totaling 355 watts of rated power. Before my next long trip I intend to buy a portable panel as well, which may be up to 100W. My total solar "capacity" would then be 455W, assuming I deploy the portable panel.

The datasheet for the Victron SmartSolar MPPT controllers says that their 100/30 controller is rated for nominal 12V PV power of 440W, and their 100/50 controller is rated for 700W. So my total planned solar panel capacity slightly exceeds the rating for the 100/30 controller. Do I need to get the 100/50 controller instead? I'm thinking that the angle of the sun will always keep the rooftop panels below capacity and the total below the 440W limit, but I'd like to hear other opinions.

If you think you may ever have the need for two portables or that new Lensun 200 watt portable looks nice, that would make the choice easier. So 100/30, no additional panels could be added - 100/50, more panels! Up to you but I hate when I paint myself into a corner.

[Mike Lewis]

Originally Posted by tdf-texas

If you think you may ever have the need for two portables or that new Lensun 200 watt portable looks nice, that would make the choice easier. So 100/30, no additional panels could be added - 100/50, more panels! Up to you but I hate when I paint myself into a corner.

You have a good point. There is room on the roof of my trailer for one more panel, if I so desire. Hmm. I want to "future-proof" my setup as much as possible.

This includes placing the new electronics (B2B charger, solar controller) under the bench seat battery area so that I don't have to move them again if I ever acquire more than two batteries. I spent much of today trying to get this right. Although I know the dimensions of the components for planning, I'll know more when I have them in my hands.