I started out with wanting to add solar just to keep my batteries charged when the RV is in storage…and then it grew from there!
I can get (3) 440w Panels JA Solar panels and I want to run them in parallel.
My batteries can only take 60A charging so my thinking is use a 100/50 MPPT but I’m concerned that the panels might feed it too much power. Victron seems to think it should have a 150/85 but these are pricey…and the batteries can only take 60A max anyway.
The panels are supposed to be 13.55A max current. Going parallel should mean 13.55 x3 = 40.65A so I’m not sure where the 150/85 recommendation is coming from but I’m probably out to lunch as I made the same system a few years back with 2 panels and saw it max the MPPT out at 50A in peak summer. Batteries are 12V
Any thoughts? This is my second solar install and it’s been years since I did the first…
I have a Multiplus 2x120, a Cerbo and a Shunt already installed.
Yeah, I think I’m going to have to go with the 150/85…
Now I’m wondering about what cable size I’m going to need…and it looks like I have to go series because the cable requirement for parallel seems to be 1/0…
You are at 12V and say that you can fit 3 x 440W panels = 1320W. At a nominal voltage of 12.0 this equates to 110A output to the battery. The default settings for the Victron MPPT Calculator is a maximum over panelling of 30%. An 85A output MPPT is the smallest fit as 85A x 1.3 = 110.5A.
What you need to do is go into features a d select oversizing allowed above 30%. Then it will offer you the 60A option.
30% oversized is an economical point for most installs, but boat or RV can often benefit from higher over panelling due to the flat orientation and unknown shading at various locations.
You can oversize more than 30% as long as you do not exceed the input voltage limit or the input short circuit current limit, the MPPT Calculator will make sure this is the case.
It seems that you’re saying the 150/85 is already on the small side. If so, then I feel better because I just ordered it It was much more than I was planning to spend.
I was originally going to go with two panels but got a deal on another one, only to find that cheap extra panel cost me a much more expensive controller!
The best way would be to use three Smartsolar 100/30 with one Module th each. Than you can use smaller wires and you have 3 MPPs. They can deliver at best sun 90A. But you bought a 150/85. Because that ist too much for the battery you can activate DVCC and limit the Battery current to 60A. Don´t limit the current in the MPP. But if you need power for a load, the Multiplus requests more power from DVCC and MPP will deliver full power. So you can use 30A for the load without decharging the battery.
This comes back to proper design and functionality and I really like the sounds of it. I can return the 150/85 and am already using DVCC.
What I don’t like about my design is all 3 are in series. I wanted parallel but this would not work due to cable size. Your design sounds like it’s the best!
How the heck would I wire that? Would it be literally 3 separate installations of solar right to the battery? I am interested in pursuing this because I want maximum performance and I really don’t like doing a series install.
I have 100’ of 10 AWG coming so I should have flexibility to change the design. Now is the time to do that. Can you help with some basic questions?
It was much more than I was planning to spend.