New install: maximize inverter power during day?

[chowderhead]

I'm assembling a new installation: Canadian Solar CS3U-375MB-AG panels (375W bifacial, Voc 47.6V, Vmp 39.8V, Isc 9.93A, Imp 9.43A) in a 3s3p array connected to a Classic 250 with a Magnum MS4448PAE inverter. The installation is for my business, which I intend to operate completely off grid and primarily during daylight hours, so don't think I need too much battery capacity. I have lots of panels - no constraints there, yet.

Is it reasonable to setup a small (200-400 Ah) battery bank, get another Classic 250 attached to a 3s3p array with the pair of Classics (using F-Me) charging the single battery bank? My logic is that the two Classics will then be able to nearly balance with the 4.4kW inverter, so I have all that power available when the business needs it the most. The inverter manual recommends a minimum of 200Ah, and I would like to stay as close to that as possible since batteries ain't cheap. I understand that low insolation days may mean curtailed production.

Playing with the Classic Sizing Tool last night indicates a 2s7p  array and a Classic 150 yields almost the same result as the two Classic 250s, above, so that seems the better way. The sizing tool yields battery charging current and max allowable current. Is the latter the limiting value or will the CC output the higher current to maintain 57.6V charging of a 48V battery bank?

Are there flaws in my plan/logic? What should I look out for or do differently? Is a WB Jr. w/ end amps enabled necessary/desirable in a such an installation?

Thanks!

PS: Initially posted in the wrong forum; sorry about that.

[ClassicCrazy]

One thing you need to size your batteries for is to be able to handle the surge needed by your inverter.  How many amps can the battery pack put out without diving the voltage or ruining the batteries is design criteria.
Are you not going to use your system loads  at all if it is cloudy ? 
If you have a huge array and small battery and no nighttime loads to speak of , it will instantly fill up . Depending on the type of battery you are using you would have to control the input power  - and the Classics do have the ability to limit input amps to battery while still providing all available power for loads .  Really a lot of your plan depends on what kind of battery you would be using to deal with proper maintenance of being in float all the time - lead acid need specific maintenance compared to lithium.
Some Lithium can deliver only 1C and some can go 10C  .
I am not a professional so these are the things to come to mind first .

Larry

[australsolarier]

9 panels doesn't seem all that much for a "business". how are you going to run your business when it is raining? particularly in winter.
i suggest you look more closely into your project.

[chowderhead]

Not even remotely helpful, astral.

I guess you missed the part about not being panel constrained. I, in fact, have 26 375W panels. Does that sound like enough to run a business? You have no idea where I live, therefore no notion of insolation. Most importantly, no, zero, nada information about my business plan.

Answer the question or don't. No one here needs you opinion.

[ClassicCrazy]

Not even remotely helpful, astral.

I guess you missed the part about not being panel constrained. I, in fact, have 26 375W panels. Does that sound like enough to run a business? You have no idea where I live, therefore no notion of insolation. Most importantly, no, zero, nada information about my business plan.

Answer the question or don't. No one here needs you opinion.

I appreciate Astrals opinion - I appreciate everyone's opinion and questions on the forums here. I often get lots of good advice and opinions from others. We are all volunteers on here . If I don't find something helpful I just skip over it or ignore it. But to your point about " No one here needs your opinion"  - I do.  Astral asked for more information of your project  and you just said  how much PV you have so that was helpful to all of us to understand what you are working with.
Thanks
Larry

[mike90045]

The higher voltage you deliver to the Classic , the more heat it generates.   about 2x your battery EQ voltage is a good setting for efficient array voltage.   This gets added to your cable length figures and you decide expensive fat copper cables or more cooling fan runtimes and hotter controllers.  some of this, some of that. 

Each controller can manage 1 PV array, and several controllers can all charge the same battery bank.

Using 2 controllers gives you a bit of redundancy.

Inverters however, need a minimum size battery bank per KW of used output.   My Schneider XW inverter requires 100Ah of battery for every kw of output it produces.  This spec controls the amount of ripple on the battery bus.  I expect most inverters have a similar spec, deeply buried in the data sheets.   I understand you wont require much power overnight, but daytime loads will need the battery capacity to buffer the battery bus like a capacitor.   Schneider XW inverters have a large bank of input capacitors with a thermal sensor, if the battery is too small for the load, the ripple on the DC overheats the cap and triggers a shutdown.   PV panels do not provide this "buffer".

If you have occasional bad weather, does your inverter easily integrate with a generator to power your loads ?