Best small MPPT?

[Simi 60]

Originally Posted by Jon Hacking

It's becoming apparent that the answer to my original question is probably Victron (depending on your definition of "best"), but you have to buy into their entire line, which gets very expensive.

Says who?

We have a Victron 5000/120 inverter charger
Victron bmv 702 battery monitor
Midnite classic 150 mppt
2200w of Jinko solar panels
and 880ah @ 24v of Yum Cha battery bank

All works a treat

[Dsanduril]

@John,

I agree, the efficiency of the DC-DC conversion (as related to different input voltage options), at least with today’s crop of MPPT controllers, is at least second order compared with other system losses. I run 48V modules in my parallel array(PO install) in theory I’d still have 32V from a module with one shaded string. Currently run 1000W through a single controller, if the other modules are still at 48V I effectively lose the entire shaded module. Hence my search - similar to yours- for a set of small MPPT units - that 32V module could still contribute helpfully.

@Simi,

Yes, you can mix and match, but to obtain functions such as the BMV integrating with and managing the solar controllers you need to install within the same family - or the Holy Grail - with systems that all speak a universal language. Does the MidNite talk with the 702 or the charger to optimize across the system? It should, but that is only marginally available in the market today. Victron FW 1.47 may change that, time will tell.

[Jon Hacking]

Originally Posted by Simi 60

...We have a Victron 5000/120 inverter charger, Victron bmv 702 battery monitor, Midnite classic 150 mppt, 2200w of Jinko solar panels, and 880ah @ 24v of Yum Cha battery bank. All works a treat

Simi, there's "works a treat" & then there's "works optimally." Your system works for you, & that's great, but is it working optimally? Most of us can't throw 2200W of solar panels at the problem. Your huge solar array is likely masking any inefficiencies in your setup, especially since you seem to be running many of your panels in parallel to a single controller.

Can your MPPT or your inverter/charger (or your alternator controller) see the current into the batteries? If not, how do they know the state of charge of the batteries, or when to switch from Acceptance to Float?

Of course, "works optimally" means different things to different people. For me, I'd like all of my charging sources to be able to see the current into the batteries, irrespective of house loads. That's pretty easy to do if manufacturers want to (many don't) & certainly necessary (IMHO) for lead/acid batteries (along with temperature sensors) but less so for LiFePO4, which only needs temp sensors on the alternators unless the temps get below freezing. Ideally, they should also talk to each other & have some unified controller so they all change state at the same time, but I haven't seen that anywhere (yet). Victron seems to be moving in that direction, & they have controllers for many charging sources, but they also speak only their own proprietary language (when they communicate at all). So they aren't there yet, but they seem to be the closest.

[Simi 60]

Originally Posted by Jon Hacking

Simi, there's "works a treat" & then there's "works optimally." Your system works for you, & that's great, but is it working optimally? Most of us can't throw 2200W of solar panels at the problem. Your huge solar array is likely masking any inefficiencies in your setup, especially since you seem to be running many of your panels in parallel to a single controller..

3 panels in series and 3 parallel strings

Can your MPPT or your inverter/charger (or your alternator controller) see the current into the batteries?

Yes

If not, how do they know the state of charge of the batteries, or when to switch from Acceptance to Float?

Of course, "works optimally" means different things to different people. For me, I'd like all of my charging sources to be able to see the current into the batteries, irrespective of house loads. That's pretty easy to do if manufacturers want to (many don't) & certainly necessary (IMHO) for lead/acid batteries (along with temperature sensors) but less so for LiFePO4, which only needs temp sensors on the alternators unless the temps get below freezing. Ideally, they should also talk to each other & have some unified controller so they all change state at the same time, but I haven't seen that anywhere (yet). Victron seems to be moving in that direction, & they have controllers for many charging sources, but they also speak only their own proprietary language (when they communicate at all). So they aren't there yet, but they seem to be the closest

[john61ct]

Originally Posted by Simi 60

Yes

Sorry if I missed it, which controller does that?

[Simi 60]

Originally Posted by john61ct

Sorry if I missed it, which controller does that?

The screen and app for the mppt shows current/amps in and battery state

The victron battery monitor shows current flowing in and out of battery,watts, amps and battery state

Originally Posted by Jon Hacking
If not, how do they know the state of charge of the batteries, or when to switch from Acceptance to Float

And this is all done automatically by the inverter charger, I don't manually switch anything.

[john61ct]

Oops, delete

[john61ct]

I assume no integration between your SC and the BMV. . .

[john61ct]

OK, checked above and there you say Blue Sky?

That display's coming from a Whizbang Jr plus a Classic SC

Confused. . .

[Simi 60]

Originally Posted by john61ct

OK, checked above and there you say Blue Sky?

Did I?
Where?

That display's coming from a Whizbang Jr plus a Classic SC

Is it?
I got the image from here where it clearly says...

The FREE MidNite Solar Local Application enables you to monitor your Classics over your local network or the Internet. It is compatible with Windows 7, Vista, and XP, and Mac OS X.

https://www.midnitesolar.com/product...tOrder=2&act=p

I dont have that set up as the display on the MPPT gives enough and reality is I havent looked at or pressed a button on it in 3 years.
The victron monitor gives all I need

Confused. . .[

Maybe.

[john61ct]

Sorry crossed wires that was the OP.

So, afaik just like all solar controllers, the Midnight ones cannot show banks' current acceptance on their own, only what they are producing, they've no idea how much the loads are consuming.

The Whizbang Jr is required in order for them to transition from Absorb to Float based on endAmps.

[john61ct]

Originally Posted by Simi 60

The victron monitor gives all I need

Of course the BMV can be used to help calibrate the usual estimated Absorb time required to get the Bank to Full as per endAmps, but the actual charge cycle will always end either over or under.

Unless using the BMV-712 relay to cut the connection between the panels and your classic, based on SoC? Not sure if that's even possible actually, Victron disabled doing so based directly on endAmps. . .

[mark0978]

I've had the MidNite Solar classic on 4 315 panels for about 2 years without any trouble. Although I've wondered if a smaller controller would be better since that is a single point of failure for all 4 panels. Also, in cold climates, the 315W panels can over produce what a Classic can handle in the tropics the best I've seen is about 1100W instantaneous power output. You can monitor it with an open source phone app for android, but that app has a few problems. I've got the remote pad in my electrical cabinet.

I bought it because is was only about $600-700 at the time.