How to best connect two different series of solar pannels. Autonomy
- one series of 4 400w 24v
- one series of 4 280w 24v
Right now they are connected on the same mppt, but. I onlyet about 1100w max
Can I have two mppts charging the same batteries? Do they talk to each other?
Thanks for your reply
Can I have two mppts charging the same batteries?
Yes.
Do they talk to each other?
For start, configure both MPPTs with the same charging settings.
Read about VE.Smart Networking. Pay attention to the requirements.
https://www.victronenergy.com/media/pg/VE.Smart_Networking/en/index-en.html
A better, but more expensive solution is to use a GX device (like Cerbo GX).
Hi, I think the best option is installing a MPPT RS 450/100, this divice it has two mppt that allow you to feed it with differents PV arrays with one unify output to your batteries. It works nice for a very similar case that I had. Best of luck.
Wirh only 4 Solarpanels in series he can run into trouble with it.
Better using two of the smallest VE.Can versions which can be interconnected ans synchronise them to the same charging voltage
You're right, he will only get 96V from each array. Maybe with two 150/50.
Hi @Kalou
If the 2 panel strings are similar in Vmp spec then it's unlikely you'd see much improvement in output from having separate mppts. Unless of course they face different directions, shade, etc. And even then, ??
Why you can't exceed 1100W is worth investigating before you choose. Both strings actually working?, batteries can't accept more? You need to provide more info to make a considered decision.
One is 28Vmp and the other 34Vmp. 6 Batteries are 750Ah.
Sorry forum has problems on my android it keeps adding spaces as I type
I've edited out the spaces. I think multiple 'Enters'.
To your panels. Not an ideal combo, but still shouldn't restrict you as much as you indicate. Usually mixing strings like that the mppt will track closer to the lower Vmp, so the higher Vmp string will take most of the production hit. A wild guess, maybe 20% or so reduction on one string. But even if it were much higher it wouldn't explain the 1100W you max at.
So there may well be something else at play. If you can isolate the strings, try testing each one separately. Give the mppt time to track, like 15 min or so if you do this on the run. Take care too, that's high panel V.
Still not much info for us to work on..
He does not mention which MPPT he has now.
The power could also be limited by the MPPT's output current.
Nominal battery voltage is also not mentioned.
I thought it was limited by the less powerful string (4×265w) which would make sense. No?
What we need to find out is what's wrong with your existing setup before you waste money on a 'perfect' arrangement.
The two string of panels go to a mppt 150/70 and charge 6 batteries Opzv before it is used through a 3000w victron converter/charger.
Thanks forbyoue interest
Ok, so it's the 12V batteries limiting you. And a 12V Multiplus, so stuck on 12V.
The only real option is to add another mppt, say a 150/100, which would be a good match for the 1600W string. The existing 150/70 fine for the smaller string. It's a Bluesolar, so can't be networked unless you have a GX device, but they'll still work ok together if they have the same settings.
And I'd wire the panels in 2x per string and have 2 strings per mppt. 4x panels in a series string I wouldn't trust to stay under the 150 Voc limit of the mppts.
Thanks a lot. Why not trust to stay under 150voc? What is the risk? Isn't there one model of mppt that could handle birh strings like it is said earlier on this discussion ?
The 150/ in the mppt name means 150V panel maximum. And that's the Voc, not Vmp. Exceeding it can destroy the mppt. You've mentioned your 2 strings are comprised of 28 and 34 Vmp panels. The Voc of the 34 one is likely around 40Voc, and 4x of those in a series string will exceed 150V. If they're actually wired in series now, then you've got away with it because the 28's have dragged the higher one down to it's level. Please don't be tempted to try the 34V string alone to see what happens. Might void warranty when it fails. Use this calculator to verify first.. https://mppt.victronenergy.com/
12V batteries come with the downside of needing a lot of mppt output power. Lets use a 14V charge V to do the calcs. Your existing 150/70 can do 70Amps, at 14V that's 1080W (about what you see now). A good match for your 4x 280(265?)W string. A 150/100, 100A@14V =1400V, ok for your 1600W string. The 170A total about as much as you'd want to put into that 750Ah of batteries anyway.
Forget the double-string mppt. Those are for high V strings (450/), and still only 100A for 2 strings. Great for 48V batts, not really suited to 12V. And more expensive!
It seems that the MC4 is cheaper : https://www.solaris-store.com/3613-smartsolar-mppt-150-100-mc4-vecan-12-24v-victron-scc115110512.html
You can use for the four 36V panels (which have probably a V0 of around 44V) the MPPT 250/100
I still have doubts, should i go for a 150/100 (is it enough) or a 250/100. They are pretty expensive
Thanks
