Help! Controllers for 2 solar arrays to 1 battery bank

[mvweebles]

I believe Nigel Calder is doing something along the lines of multi-source power management, but much more robust. I watched a video and while it seemed interesting, was also pretty complex.

But I agree - you'd think there would be a way to bond the MPPTs together and use a master charge controller. From the Victron video on the smaller Battery Sense monitor, it shows a fair amount of flexibility in configuring the system. Still hard to believe that two 3-stage chargers hooked together would be a good thing though.

Again, many thanks

Peter

[rslifkin]

With multiple chargers, they may not do equal work when the batteries get closer to full. But that's ok. And you have to be a bit careful about how they determine when to drop to float. But it can all be made to work well enough.



Personally, I went all Victron for the stuff I'm putting in so that it can all talk. I'm using one of their GX devices, however, so all of the communications are wired, nothing needs to work wirelessly.

[mvweebles]

Originally Posted by rslifkin

Personally, I went all Victron for the stuff I'm putting in so that it can all talk. I'm using one of their GX devices, however, so all of the communications are wired, nothing needs to work wirelessly.

Last year when I was making a decision on charger/inverter, I had a good friend who tried to have a generator auto-start switch installed. The installer was an exceptional electrician and while he got it figured out, it required a separate device due to his newer Onan being a 3-wire start (preheat, same as my NL). He ended up going with a Magnum which he easily installed in less than 1.5 hours.

In the last few years, I've just gotten tired of WiFi/Bluetooth contention and obsolescence issues. I work in technology (networking at that!) and frankly, I'm just tired of it. It's super cool when it works, but so very frustrating when it doesn't - getting chart updates to an MFD/plotter being one item that never fails to frustrate. I'm good with less information that's more reliable. Plus, I like all information to be accessible by whoever is on the boat (my wife) vs tucked away in an app, which is why I like an MFD vs a phone/tablet for navigation.

At any rate, the Magnum was a better fit for me - bit more analogue.

Peter

[rslifkin]

Originally Posted by mvweebles

Last year when I was making a decision on charger/inverter, I had a good friend who tried to have a generator auto-start switch installed. The installer was an exceptional electrician and while he got it figured out, it required a separate device due to his newer Onan being a 3-wire start (preheat, same as my NL). He ended up going with a Magnum which he easily installed in less than 1.5 hours.

In the last few years, I've just gotten tired of WiFi/Bluetooth contention and obsolescence issues. I work in technology (networking at that!) and frankly, I'm just tired of it. It's super cool when it works, but so very frustrating when it doesn't - getting chart updates to an MFD/plotter being one item that never fails to frustrate. I'm good with less information that's more reliable.

Peter

I'm in IT as well, which makes me picky about what stuff I use. I'll only go for the fancier features if they're useful to me.

Looking at the relay controls available, I could see generator start being limiting with the Victron stuff. I wouldn't use that feature on my own boat anyway, but I'd have to do some figuring out to make it work with my generator if I wanted to (needs a momentary signal for start and a momentary for stop, but no constant signal for run).

So far, my Victron install has gone fine (I've put in the Multiplus inverter/charger, the Smart Shunt and the Cerbo + touchscreen). I haven't added the solar portion of the system yet, that'll be in a few months (can't physically get panels aboard until we launch anyway, they're too big to carry up a ladder). Everything I've installed so far has been easy enough to configure and it's all working as it should. I went for the expensive touchscreen specifically to avoid being bound to my phone for monitoring. I wanted something hard wired and independent of any person-specific device for that job.

[Chotu]

Originally Posted by rslifkin

With multiple chargers, they may not do equal work when the batteries get closer to full. But that's ok. And you have to be a bit careful about how they determine when to drop to float. But it can all be made to work well enough.



Personally, I went all Victron for the stuff I'm putting in so that it can all talk. I'm using one of their GX devices, however, so all of the communications are wired, nothing needs to work wirelessly.

I’d agree with this post.

If you have 2 amps going in at float or near to it, doesn’t really matter what’s happening in terms of if they each produce one amp or one produces all 2 amps and the other produces none.

[facciatosta]

Originally Posted by mvweebles

I have a trawler with a hard top with a decent camber/arch. I am installing four 200W panels in two arrays as the two pairs will be tilted slightly resulting in a 10-degree difference between the two sets. Battery bank is 600AH LiFePO4.

Attached diagram ignores switches/fuses.

QUESTION: What type of controllers should I use? My first inclination was to get two MPPT charge/controllers such as these Victron Smart 100/20, but then it occurred to me that they might fight each other in modulating charge to the batteries. So perhaps there is an MPPT controller (no charger function), then a separate charge controller? I have a VIctron Smart 100/50 controller - if I can use it, great. If not, that's okay too.

I could use a knowledgeable suggestion on controller and charger selection.

Thanks in advance -

Peter

Attachment 231414

your Victron MPPT 100/50 should work just fine. In fact your 14A calculated current is overly optimistic. You'll be lucky to get 10A on a sunny day.

Make sure you install the fuse at the BATTERY. 50 A should suffice. Either at each battery or one for both. But the fuse (s) should be installed as close to battery as possible.

All other fuses are optional.

[Differentroads]

Originally Posted by facciatosta

your Victron MPPT 100/50 should work just fine. In fact your 14A calculated current is overly optimistic. You'll be lucky to get 10A on a sunny day.

Make sure you install the fuse at the BATTERY. 50 A should suffice. Either at each battery or one for both. But the fuse (s) should be installed as close to battery as possible.

All other fuses are optional.

Agree that a Victron 100/50 will be fine. In the OPs shoes I'd add another one and wire up in two banks with the same controller per bank.

A question though. When you say 14A is overly optimistic, is that 14A per 200W panel? My 180W in two panels can put out 10A maximum on a sunny winters day in Spain. My Victron 75/15 is sufficiently in spec. The OPs proposal to run two banks could easily put out 20A per bank of 400W couldn't it? Possibly 30A at peak output allowing for, say 80% efficiency. And thats what you have to spec for plus a margin for safety. So a 50A controller per bank of two panels.

Forgive me in advance if I misunderstood something

[facciatosta]

Originally Posted by Differentroads

Agree that a Victron 100/50 will be fine. In the OPs shoes I'd add another one and wire up in two banks with the same controller per bank.

A question though. When you say 14A is overly optimistic, is that 14A per 200W panel? My 180W in two panels can put out 10A maximum on a sunny winters day in Spain. My Victron 75/15 is sufficiently in spec. The OPs proposal to run two banks could easily put out 20A per bank of 400W couldn't it? Possibly 30A at peak output allowing for, say 80% efficiency. And thats what you have to spec for plus a margin for safety. So a 50A controller per bank of two panels.

Forgive me in advance if I misunderstood something

If it is 14A per panel then it is fine with me as well. Even unrealistic 20A is OK. But I am not sure where 30 A could come from. It is especially unlikely for two panels connected in series. The current will be limited by the the panel that provides less current.
it is possible to install as many controllers as you like, but 28A ( or 40A if you like) that's all you get.

For example: Power tolerance specified for my Sunpower 110W panels is +6/-3%. +6% of extra power translates only in extra 0.31A : (110W x 0.06)/21V = 0.31 A ( where 21V is maximum operating voltage of my batteries and actually this is what I observed) - this is all under best conditions). Why it should be different for any other panels?
I have no doubts the manufacturers of the batteries and of the solar panels are overstating performance of their products or rather state the results they obtained during initial tests in the lab. When it comes to the mass production it is different story especially if stuff made in China.

In any case nothing stops OP from starting with one controller and make observations under different conditions and make a final decision.