Hey everyone! I'm working on expanding my off-grid solar system, and I have a question about wiring. Right now, I've got one MPPT hooked up to my inverter, but I'm planning to add a second one to boost my solar capacity. My inverter is a Victron MultiPlus II with a 120amp limit, while my MPPTs are Victron 250/100 and 100/50 models, all running on a 24v system.
So, can I connect both MPPTs directly to the inverter's DC terminals without using a busbar? I know the inverter can technically serve as a busbar, but I'm worried since the peak output could hit 150 amps while the inverter is rated for only 120 amps. I've seen setups using a busbar to keep things stable, but this seems like it would simplify my wiring. Has anyone connected multiple MPPTs this way? Were there any problems? Or should I stick to using a dedicated busbar for better safety? Thanks for the input!
3 Answers
Also, I noticed there’s no mention of a battery in your setup. You should definitely consider how that ties into your overall system, especially with the load and capacity you're discussing.
It’s not a big issue as long as everything is secure and the wiring can handle 150a. Still, I’d recommend transitioning to a busbar system or a combined busbar and fuse holder setup. This approach cleans up your wiring and can prevent issues down the line. Just make sure you have the right components like a battery disconnect switch to keep everything safe.
The original MPPT and inverter were set up using the terminals, and that was for 100A. Now, I'm bumping it up to 150A, and it feels like I'm going to have to redo everything just to add this second MPPT. I’m just a bit frustrated!
You could connect both MPPTs to the inverter terminals, but just because it's possible doesn't mean it's the best choice. Using the inverter's terminals like a busbar can lead to issues since those posts are usually sized for the inverter's own consumption, not for handling power from two sources plus the loads. It’d be better to use a dedicated busbar for a few reasons: it helps with proper circuit protection, allows for emergency disconnects, and lets you use the appropriate wire sizes without overloading any single connection. Plus, with 150A flowing through those posts, don't underestimate the heat they can generate!
Is any busbar rated over 250A good enough? I can find a bunch on Amazon for around $20, but a better one, like from Blue Sea Systems, is closer to $50-60. I just want to add this second MPPT and the original install was done by a professional who used the inverter terminals, which is why I'm asking if it's worth the hassle of changing it all.
Is this busbar from Amazon a good option? It looks solid and is rated for the current. Just want to make sure I’m getting something reliable before switching things around.
I do have a 25.6v 280ah LFP battery in the system.