Noob with panels/batteries/batteries/batteries and LOTS of questions

OldPhart
OldPhart Registered Users Posts: 5 ✭✭
edited April 2020 in Solar Beginners Corner #1
Hi-

I'm an old guy with a collection of stuff that has sat long enough-I finally decided it all needs to get put together into a working system sometime before my upcoming expiration date...

THE PARTS
Trace 3624 inverter circa 1999-hardly used
40- 250w/24v used tested good polycrystalline panels 
4- 75 w 12v mono panels

4- Rolls 6CS 21 FLA batteries @ 20 Hour Rate 710 AH-always kept watered, floated with BatteryTenders, charged with cheap 12A automotive charger every couple of months but not equalized
200 pack - 3.7V 8AH 200A LITHIUM ION POWER - SPIM08HP                 
~300 18650 2400mAh Sony and LG used cells
~200 LiFePO4 A123  26650 cells used tested good

Currently thinking my inverter budget is about $2000 tops but I suppose a very good argument for a more expensive one could sway me higher...

Saw a couple of very positive YouTube reviews of the MPP-SOLAR LV5048 inverter-contacted the company and got little help with my questions.  Here is the email I sent-

>>Watching "Texas Filipino" YouTube video on this inverter and want to be certain I buy a genuine MPP product, not a knockoff.  Have 40 [10KW] of 250w 24v panels [polycrystalline], 4 matching Rolls 6v LA batteries [forget exact capacity just now, thinking ~ 3KWH available @ 50% DOD] which have never been used, just watered & charged every 2 months for a few years now, ~2 KWH used LiFePO4 cells and probably about the same amount of used, tested good 18650 cells ranging from 1600-2600 mAh capacities.  Also ancient Trace DR 3624 modified sinewave inverter [120V only but now we are wanting 240v capability].

 Wanting to build an offgrid system [with grid backup] capable of supplying power for an efficient home which averages about 600 KWH grid usage monthly.  [The monthly electric co-op connection fee is nearly as much as the cost of the electricity used.]  Electric stove [willing to swap to propane if needed],  propane water heat, propane furnace, 15 yr old refrigerator, new EnergyStar 15 cu ft freezer, 2 window AC units [5000-12000BTU] used for  ~ 4 months, LED lighting throughout and electric clothes dryer [which we can swap out for propane if needed.]  Excellent southern exposure of  4/12 pitch roof for solar panel mounting.

Need 240v/1ph to start/run 3/4hp deep well submersible pump

 Garage has 240v 50A service for very occasional arc welding and other power tool use.

 All this info hoping you can tell me if this inverter will be suitable for my purpose.  I realize it can be expanded if necessary by buying a 2nd unit.  Seeing a CE certification but not UL..<<

They forwarded my mail to the US distributor and a few days later I received this reply:

>>Hello Dean sorry foerthe late reply.They are not UL listed.  UL listing is mainly required if feeding back to the grid (which these do not do).  But some regions of the country have differing rules.We are extremely short on stock arriving, we are completely sold out in the US, and factories are not able to supply in any reasonable qtys.you can pre-order at usa-mpp-solar.com, and click the "store" icon, and check out with PayPal if you so wish.  Not sure I would put an Arc welder onto my inverter.

Ian Roux<<

So far, my followup request for more info is unanswered, as were most of the questions I posed in the original email. 

In doing more research, seems that my 24v FLA battery bank will not work with this inverter so I would likely need to use the SPIMO8HP lithium cells to construct a ~ 6KWH 48v battery.  Alternatively, I could use the 18650's or the 26650's to do the same thing though with smaller KWH capacities.

My questions to this forum are:

1.  Would one of the $100 stepup transformers paired with my Trace 3624, the 300 watts of 12v panels and the FLA battery bank in a standalone system work for the well pump?   Since this is in Western Montana there would be a challenge in keeping the FLA batteries warm and it might be better to use 26650's or 18650's in this application?

 2.  I can ALMOST start the well pump with my Honda 2500w genny, have wondered if adding a couple of big caps would push it over the hump?  If so, where can I go to learn more about how to do it?

3.  Are there better inverter choices out there than this one anywhere near this price point?   The LV5048 seems to have so many bells and whistles and the ability to charge multiple battery chemistries at a price point not all that much greater than a PowerJack...

4.  Is it possible to have multiple battery banks of differing capacities and/or chemistries connected to the same inverter if the voltages are the same?

5..  Is it feasible to connect the 24v FLA bank to the LV5048 using a transformer, realizing there would be higher losses if it is even possible?

6.  Would I do well to buy their LV2424x2 Hybrid package in order to have the 240v capability to run the well pump and be able to utilize the 24v FLA battery bank?  Pricing is comparable to the LV 5048, at about $1300 USD delivered and purchasing more units can expand the system up to 9 parallel units. 

I understand the advantages of a 48v system as far as smaller wire sizing/connectors/lower losses etc but have no clue as to their magnitude in a 24v vs 48v system, only that a large 12v system gets pricey fast for those things. 

The 2 built in 80A MPPT controllers are a huge plus it would appear, the genset start/60A charger/3-stage charging etc all seem to be a huge value-but I confess I have only the company sales hype and 2 YT videos to support my enthusiasm...

6.  Why is running an arc welder bad for an inverter if it is split phase and rated at least twice as much wattage as the arc welder would ever pull?  {~20-24v @ 100A on 240v 1phase]

Whew!  Sorry for the book-length post but wanted to provide as much info as possible to allow for more informed replies.  Thanks to all who respond!

Edited for clarity a few times-us old pharts don't always track as well as we usta could...

Comments

  • 706jim
    706jim Solar Expert Posts: 514 ✭✭✭✭
    40 panels, wow! I figured I was doing pretty good with six. I can't comment on every question but have a few suggestions.

    Do you really want 40 panels on your roof? Would you have room to put them on ground mounts?

    Even with all that charging capacity, I would go with a gas stove and dryer. Much more practical than having an enormous battery or working around sunny days for cooking and drying.

    Don't throw that old Trace away. I have a similar albeit smaller DR unit and it has been absolutely bulletproof since 1994. From comments I've read here that is uncommon reliability compared to many newer inverters.

    As for the welder, I don't weld but I know my Trace seems unhappy running an ancient 12 volt battery charger; maybe the welder is a similar sort of load.

    Suspect you will get many more useful comments shortly.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 30th year.
  • OldPhart
    OldPhart Registered Users Posts: 5 ✭✭
    edited April 2020 #3
    TYVM for quick response.  No, I don't think I'll want to just toss that Trace-saw one on FleeceBay last week for a cool $1000-...dunno if they will get that much for it or not.  Was thinking if I COULD pick up another one at a reasonable cost I could stack them and my 240v well pump problem would be solved.

    So you have run that DR1524 nonstop for going on 27 years??  That is quite a testimonial to how well they made 'em in the good old days!

    The 40 panels were an eBay buy at a bit under $40 apiece [$50 incl shipping] that I just couldn't quite pass up.  Seller still has some available if you need more:
    eBay item number: 283399898474

    Been considering ground mounting for about half the panels if it turns out I really only have need of 4-5K watts.  Problem here is many overcast winter days so even though in summer I'd obviously be having to dump power to heat water or greenhouse passive heat storage or whatever, in winter it might turn out that I'd only produce 4 or 5 kwh on those really dark and snowy days.  Since there is a 2nd floor deck that runs the full length of the house on the S side I could even mount some on there, making snow removal quick and easy.

    Figured I could always resell any I find are overkill for my purposes.  Am discovering that the wife is surprisingly resistant to the idea of cooking with propane-kinda set in her " 'lectric cooktop " ways at age 65...maybe when she finds out she can't cook after dark she will soften her position a bit-

  • 706jim
    706jim Solar Expert Posts: 514 ✭✭✭✭
    Just one quick comment. At my house we have an electric cooktop. She hates it wants gas.
    At our camp (the one with the solar system) we have propane and she loves it.
    Not saying one is better than the other but maybe mention it to your better half.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 30th year.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Re point 1 and trouble keeping FLA batteries warm... fully charged lead acid won't freeze (to ~ -75°).  Even at 50% charged it has to be pretty darned cold to freeze them.  Low temp does reduce capacity though (mine are reduced by maybe 1/3 at ~15°f).

    You would not want to use any sort of lithium instead.  They have to be warmed to above freezing to charge or permanent damage is likely.  This can be done (as in EVs) with internal heaters, but that adds complexity and robust controls, etc.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,731 ✭✭✭✭✭✭
    edited April 2020 #6
    Good to see you back Estragon.

    Another little dirty secret I am hearing from offgrid installers is even LFP the (safe one) can get very nasty when charged below freezing. I mean nasty like losing the house.

    Divorce or worse, would soon follow loss of propane cooking.

    The OP should start doing alot of EQ on those batteries. Get some SG reads  and hit them with the Rolls spec V. Do a preventative EQ and then get ready for some long corrective EQ's if they have set that long.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    You will be converting your electric heating appliances to propane.  maybe use a induction hot plate for special purposes or sunny daytime use

    You will be buying new, efficient  air conditioners, or spending more on power system (and new energy star fridge)

    You will stay with lead acid batteries, if you have trouble keeping them warm, lithium will give you even more trouble

    What is the consequence of your off-brand inverter going dead in 7 months ?

    Do you have a backup generator and fuel to run for a week until spare parts arrive.  You will also weld using your generator, not the inverter.

    Have you thought how you would wire up hundreds of little Li batteries, how to monitor them?

    And finally, your well.   Do you need 3/4 hp pump ?  can you manage with a 1/2 hp - would it keep up with slightly modified water usage (not running 4 taps at once)  Is it a 3 wire controller (capacitor at top in box) or 2 wire (cap in pump housing in well)
     You will need to see if your inverter can supply the starting surge without all your lights dimming, or your air conditioner shutting off.


    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • OldPhart
    OldPhart Registered Users Posts: 5 ✭✭
    edited April 2020 #8
    @Estragon-TY for that-I was aware of the FLA resistance to freezing if kept charged, my problem with using them for a standalone wellpump system is lack of space in the 4x4 wooden insulated above-ground wellhouse.  I suppose I could buy a set of Trojans expressly for that purpose and a 24v 4000w 240v-only inverter and use 500w of panels in a system dedicated to water pumping only. 

    Present pump is 3/4 horse 3wire which has performed flawlessly for over 20 yrs so it's probably well past it's expiration date as I bought it used and set it myself after a 30 min crash course from the guys who sold me the wire, PVC downpipe and vibration dampeners.  Installed the largest pressure tank Home Depot sold back then, [thinking 80 gal nominal, probably only provides 20-25 gallons per cycle @ 50PSI.]  The well serves 3 households but nobody wastes much water.  Downsizing to a 1/2 hp 120v is certainly possible and I have one in reserve should the pump go boobs-up.

    Have looked at solar slow pumps and fear they would not be up to the job on at least some occasions @ only 3-4gpm.

     @DaveAngelini-TY for the EQ reminder and also for the LFP freezing/charging issue.  I have a 50% earth-bermed ICF basement [unheated] where nothing has ever frozen since construction in 2002 even when it hit -28F one winter so I'm not too worried there.  Might consider an insulated [but still ventilated] battery room in the basement with a 15w bulb for heat just for insurance though-

    @mike95490-LOL-I DO have a generator, 3 actually...a 900w ancient little Kubota for camping, a 2500w Honda that has served me well during offgrid construction projects, and a 7.5kw surplus military diesel genset on a trailer with 40 gals red diesel preserved with PRI-D so I can function for quite awhile if needed.  Thanks for the pump table-very helpful.  Looks as if substituting a 1/2 hp 120v pump for my present 3/4  hp 240 v one would reduce the starting surge capacity needed from 7600+ down to "only" 4100.  Since the 2500 watt Honda genny seems to be close to starting the 3/4 it would likely have enough grunt for the 1/2.

    Regarding the "hundreds of little Li batteries", I  originally bought 'em for bigger/brighter/ better LED flashlights.  Then I discovered how to rebuild dead cordless tool battery packs.  Since I am a cordless tool junkie this is a valuable skill.  Then I discovered the YT videos of "JehuGarcia" and several others who have built their own Powerwalls with up to 100 kwhrs [no typo] of storage using 18650 cells.  It would be somewhat tedious but as I am pretty good with detail-oriented tasks like that I have few qualms about tackling it.  The YT gurus show in some detail what their BMS and monitoring setups are and a couple are really good at fielding questions from their viewers.


    Please note the brand of inverter shown in the 1st photo...yes, it is the same as the one about which I am inquiring here with no bites thus far...MPPSolar...

    Still open to any/all of you giving me opinions on this inverter or trying to sway me to a different brand.   Not sure I'm too open to a PowerJack unless someone here knows all the tricks that that Aussie guy [Oztules] did to his PJ's to make them really robust and reliable by replacing MOSFETS and caps and adding big toroids and is willing to hold my hand while I tiptoe through a completely foreign electronic landscape to turn them into 10KW split-phase Goliaths...[-:

    Unanswered questions:

    1.  WHY is welding using an inverter that is at least twice as large as the max kw being drawn a bad idea for the inverter?  My very limited formal education in the field of electricity was nearly 40 years ago and that was only for 1 semester.  I have managed all home electrical projects all these years-adding circuits, outlets, lighting, switches, furnace/washer/dryer/water heater repairs etc. without frying either myself or anything of value but have almost zero theory.  Red to red, black to black, green=ground...except when there's a different colored wire screwed to the frame of something-then I have to dig out my free HorribleFright meter and start playing around.
    2.  Would adding largish caps be likely to give my 2500w Honda genny enough of a push to get that 3/4hp well pump started?  It comes close now but seems to bog down and die about 2 seconds prior to the pump getting over the hump.  If so, where can I go to learn more about how to do it?  Google seems to be less helpful by the day-my search strings are very specific but their results are almost completely ad-driven these days it appears.
    3.   Would one of the $100 stepup transformers paired with my Trace 3624, 500 watts of panel and a pair of T-105 or equiv. FLA batteries in a standalone system work for the well pump?  I think I could spare 300whrs/day to keep those smaller batts warm with a light bulb in winter.  Probably wouldn't need any fancy temp sensing beyond an LED indicator on the outside of the well house-no light=better bundle up and go see if the bulb is burned out.
    4.  Are there better inverter choices out there than this one anywhere near this price point?   The LV5048 seems to have so many bells and whistles and the ability to charge multiple battery chemistries at a price point not all that much greater than a PowerJack...just found an ancient thread on this forum about MPPSolar inverters and it looked to be ~60/40 negative...but a lot can happen in 10 yrs to make a crappy product better-or a great product crappy-Craftsman tools come to mind....
    5.  Is it feasible to connect the 24v FLA bank to the LV5048 using a transformer, realizing there would be higher losses if it is even possible?

    Yet another novella-length post...sorry, guys-I'll try to knock off the coffee at least 2 hours prior to posting from now on-




  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    There are gadgets called "soft starters" also called "hard starters" which electrically play with the motor to make it need less surge to start.  Your pump needs to be a 3 wire style for this to work.
    240V pumps start easier, if you have a 240V inverter
    https://www.achrnews.com/articles/119718-the-case-for-hard-start-kits
    https://georgebrazilhvac.com/blog/what-is-an-air-conditioner-hard-start-kit
      Same starting principal for all motors.  But the kit is sized to match the motor size.

    Welding.   Because the arc starts and stops many times in a second, as you weld, the rapid on-off-on-off drives the control circuits in the inverter crazy, and is simply not a recommended use,


    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,731 ✭✭✭✭✭✭
    Welding is fine for an XW in my opinion. You just need a spare one if it lets the smoke out. Use a genset for offgrid. 
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • OldPhart
    OldPhart Registered Users Posts: 5 ✭✭
    TY for the welding explanation-I can wrap my peabrain around that.  Got curious what Lincoln Electric says about running welders on generators-turns out they say you need 15KW genset!!  However, plenty of anecdotal info that people run oldschool AD/DC bricks on considerably smaller ones so I'm guessing my very conservatively-rated military genset will be able to handle my Lincoln buzzbox.