Battery Selection - System Sizing

littleharbor2

nobadays said:

The solution seems to be, different panels. After a little shopping I located some 305W panels with a slightly lower VMP and VOC which will be well within the parameters of the CC and still give me all the charging capacity we should need, and less than $4.00 more than the other panels.  Thank you again for helping out!!


Don

If you need the amount of wattage in your design you should look into the 300+ watt 60 cell panels that are being made these days. You can get the same amount of power in an equal number of SMALLER panels that have lower voltage to fit more comfortably into your charge controllers limits, with higher amperage to make up for the lower voltage. Plus they're easier to handle when mounting on your , probably steep, high altitude roof.
 Something to think about.

wellbuilt

I just thought I would jump in with some of my  minimal experience and knowledge . 
 I have been here asking guestions for 4 years an the guys here have helped me 
  Immensely  and still are . 
  But in all the time spent on line reading , I still had no direction . 
   I was trying to build my system as inexpensively as possible but in the end I just called over to
 our host AWS and told them what I was planing and they worked up a system for me in about 3 hrs . 
  I ended up with a out back system  FP1 36/48 with a fm 80 cc mate and  battery monitor .
  When you add up all the parts and goodies that go into the  pre built system  it doesn’t really save very much  $$ assembling yourself  , my system needs to be inspected and there isn’t very much for the inspector to look at with the FP1
 I could of used a smaller inverter but the fp1 system with a smaller inverter  uses about the same watt per hour and has a smaller battery charger built in .
 I have 2 string of 8 GC battery’s from Costco. 
  They gave me some trouble at first but the cells seam to be evening out now. So I think they are a win . 
   I bought my panels from a Electrical supply house locally so there was no shipping cost but I payed sales tax  I ended up with q cells 295 watt for 167 $ each . I bought 24 panels at first then picked up 7 more 
 to run a second ground mounted array  5 strings of 3  on a second fm 80. 
 I have 1 extra panel . 
 I draw warm air thru the house to vent the battery box and keep the battery temp up .
 My batterys live in the garage and I have a utility room for my water   Manifold    Radiant heating  equipment and my well tank . 
 I have 15 panels on my roof that get snow covered ( real bummer buy the way ) so I bought a Honda genarator 2800watt unit ,it works really well with my system I’ve been running on battery power for 3 days and charging the bank up on Monday before I head home .
 So when I get to the house fri night I turn my system on and it’s sitting at 100% full , over night I use 10to13% battery  capacity  .  Small frig ,Lights radio , 55” tv and outside lights all around C-pac
 I leave the inverter on all night . 
I use about 20% of my capasety in 24 hrs with snow covered panels . Up till nov 15 I’ve been getting up to 100% charge every day even   Though It’s been dark and raining for ever . 
           Hopefully some one turns the sun back on at my place .     Just some of my  experience so far    John 

wellbuilt

This is my power panel in kit forum I did not buy the kit but I am impressed with the out back equipment . 
Gc  Battery’s from sams club are about 100 bucks each I ran my system with 8 battery’s and 2 strings of 3 panels for most of the summer . 
          Of  Cours I have limited experience with this stuff John 

nobadays

Wellbuilt.... Thank you for your info and experience with the Costco batteries.  Not sure if I  will use those or not but leaning that way.  Likely I'll fry them in the first year or two from my inexperience with this size of solar system. So cheaper batteries will mean less money lost.

I did a price comparison between Outback and Schneider... both respected it seems... Schneider comes out the winner for me, all things considered.  So far NAWS has the best prices on most everything I will need. I already figured I will sit down with them and see what kind of a deal they will give me on the equipment I have chosen... and listen to their suggestions if they feel changes would be better.

Thank you 
Don

littleharbor2

nobadays said:

Wellbuilt.... Thank you for your info and experience with the Costco batteries.  Not sure if I  will use those or not but leaning that way.  Likely I'll fry them in the first year or two from my inexperience with this size of solar system. So cheaper batteries will mean less money lost.

Short of using used batteries, bad idea,  the Costco GC batteries are about the best deal out there.

nobadays

Littleharbor2.... That is precisely my dilemma. I occasionally see used batteries on Craigslist and have considered going that direction... but fear I will be just paying a whole bunch of money on a "core charge." Right now I see a guy in Prescott that has L16RE-Bs @ $140 ea - supposedly 2 years old, a matched set, used lightly.... tempting.

Don

mcgivor

Buy new, that way the history is known, there are so many things that could have happened with used, why take the risk? New Golf cart batteries are worth far more than a second hand set of unknown 2 year old larger capacity batteries. My opinion only.

wellbuilt

I went with the outback equipment since I have had some experience with them , I think they are all good .
 If you buy from AWS the guys there have more  experiences with the outbacks stuff   And most everybody that answers the phone could help you with set up and troubleshooting .
  I don’t know about your experiences but a lot of the solar stuff is just way over my head . 
 I’m a builder I’m building a off grid 2500 sf house  in the middle of nowhere .
 The solar system is just a small part of the build . 
  I would not want to work with used battery’s.
    I’m glade to give back to the forum  john
 

Estragon

I've heard of people getting used batteries (eg telecom backups, which might get swapped out on a schedule, just because) for local scrap value or a bit less just to save the P.O. the expense/hassle of hauling.  Might be worth a shot at that price if you're equipped to handle them.

Supposedly 2yr old L16s at $140 doesn't seem tempting at all to me though.

nobadays

Mcgivor/Wellbuilt.... yep I agree on the batteries, as tempting as it is $140 for a core charge would be foolish!  I live just south of Flagstaff so when all is finalized on the cabin... (still waiting on the appraisal- don't expect any suprises) I  will go up to Flag and sit down with the folks up there and go over all the numbers and my (thanks to this forum! ) design.

Don