Too Much solar, a Good problem...

Photowhit
Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
My good luck and good fortune and perhaps divine intervention has presented me with 2000 watts of panels at a very low cost (think haul them off).

I have been preparing to take my new place off grid, I have 4Kw of panels already and had planned on using with my new traction battery which is 800Amp 24 volt battery, with 2 - 150 amp midnite classic 150's.

My high use is in the summer time to run an AC, if I add the new 2Kw of panels I can give a pretty hot charge to the batteries, 6000watts/24v = 250AMps x 90% max (summer time, I'll gladly pull strings for winter use) 225 Amps, over a C4 rate. Mostly charging will be at higher voltage and warmer panels during the summer, more likely could derate/adjust voltage for 70% or about 175 Amps. Temperature monitored I think the battery can take a C6 charge...

So I'm looking for options and even growing the system options.

I could set it all up and put the new panels on a relay to come on with my AC, The AC won't be a constant load, but if I did this I could have the whole thing run for an hour (which would mostly be a steady draw) and shut down, or I could set the thermostat where it would run steady (while I wasn't there at least)

I could pop for a reconditioned 48 volt battery, at $2500-3000 not a cheap alternative, But I could plan for the future, even get a split phase inverter rather than a split unit AC and run the 10 year old central air.

Any ideas, thoughts, congratulations...

I really have been a small solar guy, had even planned on using my 1800Amp prosine to run my whole modular home, still plan to dump the Stove and add cabinets, and add induction table top, only running a split ac in the living room area or a window AC in the bedroom.

To avoid confusion, I have an existing 2Kw array which will continue to live at the cabin I use to live at, not rich cabin is 10x16, 2000 16x60 Modular home on 2 acres was $12K I couldn't pass it up. Only the battery and the 20 - 200watt panels were planned to move to the new place from my signature.
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.

Comments

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Too Much solar, a Good problem...

    Photowit, I would hold on tight to those reigns... start small and learn what the new panels can do for you, in a 'traditional' setup then start experimenting .
    Did you read the Sandia lab report re charging? post #1 http://forum.solar-electric.com/showthread.php?15475-Burping-the-battery/page4
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: Too Much solar, a Good problem...

    As you said, a very nice problem to have! ...and I don't actually see what the problem is, you can configure the maximum charging current in the midnites, so why not just have all the panels connected permanently?
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: Too Much solar, a Good problem...

    I didn't realize you could limit the charge capacity w/Midnite classics, makes sense, just never needed to in the past...lol

    -Thanks
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Eric L
    Eric L Solar Expert Posts: 262 ✭✭
    Re: Too Much solar, a Good problem...

    This is what I do too; limit the output amps on the Classic to avoid overcharging and it's no problem. It is a bit strange at first with a high panel power:battery ah ratio to observe your system in full sun and know that it has been 'clipped' and will not operate near full capacity. But then on a cloudy day, as long as there's at least a little sun breaking through, you'll often complete a full absorption charge, which is pretty cool.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Too Much solar, a Good problem...

    The wonderful thing about having "too much" PV, is that on most cloudy days you still have plenty power :)
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: Too Much solar, a Good problem...
    Photowhit wrote: »
    I didn't realize you could limit the charge capacity w/Midnite classics, makes sense, just never needed to in the past.

    You can also limit output on the Outback FM60 or FM80. I don't know if the MX60 does that also, but since you have a mothballed MX60 it might make sense to check.
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Too Much solar, a Good problem...
    vtmaps wrote: »
    You can also limit output on the Outback FM60 or FM80. I don't know if the MX60 does that also, but since you have a mothballed MX60 it might make sense to check.
    --vtMaps

    Yep, it will.

    Funny, that. Why it's almost as though the Outback and MidNite controllers were designed by the same brilliant minds! :D
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: Too Much solar, a Good problem...

    I've yet to find a forklift battery manual that says that the initial bulk current must be limited. Every manual I've read only talks about limiting the current once the gassing voltage of 2.4V has been reached. Here's an excerpt from the battery technology handbook which refers to the IUIa charging profile (Bulk, Absorb, then current limited charge to 2.7V)

    Attachment not found.
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: Too Much solar, a Good problem...

    ...and the paragraph below describes the regular Bulk, Absorb cycles:
    Attachment not found.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Too Much solar, a Good problem...
    Yep, it will.

    Funny, that. Why it's almost as though the Outback and MidNite controllers were designed by the same brilliant minds! :D

    Shocking as it might sound, I really think you may be onto something there Coot! :D:D
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: Too Much solar, a Good problem...

    Well I'm not the one with an MX60 in storage, but my 2nd bedroom now has 6.5Kw of solar.(but they don't seam to produce much...lol)

    I'm kinda sold on the classic, a classic 150 I think would handle 12 of the 185watt panels (Voc is 45 so I'm close, low is -15 on 24v system, 92.5 amps in theroy but I guess I can limit that I think 92 amps is max at 90 volts, just from memory, plus it's not 100% effeicent.... Something for the Midnite forums)

    I just got back to where I borrowed the truck, they wouldn't listen to me and leave them in the boxes, even with the damage, I could have brought the corners from my evergreen pallet(a great way to ship!)...but I was a100 miles away when I found out. so I stacked them with a bad panel on the bottom all good glass up frame against frame and shrink wrapped them well and they mostly survived the trip, the bad panel on bottom fell inside the bottom frame and ripped the backing a bit, but must have happened in the last mile of gravel road. 3 others that were intack have some scratchng on the backing, I'll do my liquid electrical tape thing, which has work for 5+ year on my Evergreen 115 cedar panel.

    The good ones look pretty good, I'll put a meter on them some day, the cracked ones have 4 with no chance, 4 that might have a chance and 4 likely to be servicable with the glass covered with another pane of glass or plexy. I'll put a meter on those.

    Another thought, If I went the 48 volt battery route, I could use just one midnite classic with the 4Kw of panels and put these 24V nominal on 2 C40's, so about $1000 less... Once I move the Fork lift battery I'll have to put 8 golf cart batteries at the cabin... is I have another $700 toward a 48V battery, I think Mike said he had good luck with a reconditioned 48V traction....More to think about.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.