Panel upgrades

[BlackwaterPark]

Many thanks to both of you for weighing in on this. 

Larry, I was looking at some LiFePo4 companies, and have dinner some basic math. Even considering the upfront cost, I would not have an issue going with the LiFePo4s, but for the fact that they only warranty their batteries of you have certain inverters, which are neither of mine. The ones that they do approve are all the big expensive ones that I just don't need, which would also add another $1500+ to the deal.  I can't see spending $6k on batteries that do not come with a warranty, unfortunately. (This was in an ongoing email with Simpliphi, anyway...I haven't checked in with any others like Battleborn. Maybe I should).  Additionally, because I'm still confused about what I've heard... I'm to understand that LiFePo4 doesn't like to be charged above 90%?  Leaving the capacity gap a little less dramatic of that's the case. THREE times, dusting email exchanges, I asked Simpliphi to explain to me whether or not this was indeed the case, and the question went competely unaddressed. So I still don't know, but it kinda left a bad taste in my mouth.

VIC,
Perhaps a better question to pose to you would be to ask what I should be looking for to take maximum advantage of a single classic 150 in Maine? Then I can rebuild the bank around that array? I'm hoping to go to the AltE store (3 hours from me) and pick all this up by Friday...or civilisation collapses, whichever comes first, lol. I'm not worried about factoring in for my loads, I will work around what I end up building. I've been getting by just fine on less than what I'm upgrading to anyway.

[ClassicCrazy]

yeah i wasn't talking about those expensive lithium batteries - more about ordering lithiums direct from China and installing your own BMS.
Look in the battery section of the forums here for a recent post.  Everything is always a bit of gamble with lithiums.

Larry

[Vic]

Many thanks to both of you for weighing in on this   ...

VIC,
Perhaps a better question to pose to you would be to ask what I should be looking for to take maximum advantage of a single classic 150 in Maine? Then I can rebuild the bank around that array? I'm hoping to go to the AltE store (3 hours from me) and pick all this up by Friday...or civilisation collapses, whichever comes first, lol. I'm not worried about factoring in for my loads, I will work around what I end up building. I've been getting by just fine on less than what I'm upgrading to anyway.

Hi Black..,

For a 24 V system,  running PV String Vmps around 60-ish Volts should be close to ideal.  For 60 cell PVs,  like your targets for the panel upgrade,   strings of two should be fine,  and you will have no worry about excessive Voc.   Also this is a good operating point for CC efficiency.

You could get some benefit in trying to use the two existing PVs on a PWM controller.  This would give some charge,  into the Absorb stage,  but not contribute much with cold batteries in Absorb,   and probably nothing contributed in EQE

EDIT:  Should have mentioned,   above,  that if a PWM CC was chosen,  the  two PVs should be in parallel.<

This is my drive-by opinion,   FWIW. Good Luck, Vic

[BlackwaterPark]

Thanks Vic. I just ordered 4 of the Trojan premium 377ah L16s, supposedly optimized to be and to run in partial SoC better than typical FLAs, so I'll size up from there with the panels.

Looking at this Peimar panels, if I went with 3 strings of 2 panels, the sizing tool yeilds:

Rated pv power: 1860w
Pv array current: 28.53
Battery charging current@28.8v: 64.6
VMP: 65.2v
VOC: 81.4v

If I'm trying to stay within Trojans recommended 10-13% charging current, is this to say that the  "pv array current" should be 37-49a?

The battery charging current at 28.8v goes way beyond that though.

With 4 strings of 2 panels:
Pv array current: 38.4a
Battery charging @28.8v: 86.1a
VMP: 65.2v
VOC: 81.4

Is the 8 panel scenario better than the 6 for this bank? If we are going by the "pv array current" metric, that looks to fit neatly into the 10% charge rate, of this is how that is supposed to be factored.

[Vic]

Hi BwP,

WIth 8 of the target PVs,   would consider that the Cl 150 is maxed out.

Did not use the Sizer,   just used the total STC power from 8 PVs,  derated that to 80% of that total  (at solar noow,   PVs produce about 77% of STC in nominal WX conditions,  in full sun).   Divided that number by 29 V.   8X310=2489W.   80% of that is 1984W.  At 29V  this is approximately 68 Amps.   This is just a simple rule-of-thumb.

There is an ability to limit the battery charge current in the Classic,  using the WbJR.  This is described in the Classic Knowledge-Base,   here:
http://www.midniteftp.com/support/kb/faq.php?id=37

On my computer the this info seems very sluggish to access,   and at times,   the access simply fails.  This may be some bottleneck,  just now,   or perhaps with my Win 10 system.

Believe that this battery charge current limit function will work with a single Classic.

Will look at the Sizer data for 8 310 W PVs.

Good idea,  on the L-16s.   Failed to comment earlier   â€¦   Avoiding multiple strings of batteries  is almost always better than  trying to get Capacity with parallel battery strings.

Later,  Vic

[ClassicCrazy]

VIC,
Perhaps a better question to pose to you would be to ask what I should be looking for to take maximum advantage of a single classic 150 in Maine? Then I can rebuild the bank around that array? I'm hoping to go to the AltE store (3 hours from me) and pick all this up by Friday...or civilisation collapses, whichever comes first, lol. I'm not worried about factoring in for my loads, I will work around what I end up building. I've been getting by just fine on less than what I'm upgrading to anyway.

You better call Alt E before you drive down there - they just sent an email saying their customer pickup is closed now.

Larry

[Vic]

BwP,

Looking at four strings of two 310 W PV,   shows that one Cl 150 is fully-utilized.   Result Attached.

FWIW.    Good luck,   Vic

[BlackwaterPark]

Yeah, I called them this morning and they had the warehouse pickup open. They must have changed that at some point today. Hopefully, they can still ship them to me in time, before even shipping is shut down, if that ends up happening.

[ClassicCrazy]

I don't understand why it would bother them to have people call first and then come so they could bring the order outside for them to load ! Anyway hope you get your new PV and stuff to play with before you get shut in for awhile !

Larry

[BlackwaterPark]

Thanks Larry. I'll at least have the batteries, though my 500 existing
watts will be rather meager for the bigger bank. But at least I've got the charger and lots of gas to keep them charged until I can get the panels anyway.