Extreme load shifting

All:

Long time reader, first time poster. I need some help from you experts.

First, let me start by saying that the home I live in is horrible for any kind of solar -- yet I know I will own a remote cabin/home type property in the next couple of years that will be perfect for solar/battery. I also plan on buying a system before dec2016 to take advantage of the tax credits even thought I might not own a property by then.

In the mean time, I have some free high quality batteries, factory racks, and all interconnect cables. Currently, I have 80 12v 94AH high current deep discharge batteries that live for 12 months in a critical Liebert UPS system and are discharged for 15 seconds (probably discharged no more than 20 to 30% of their of their total capacity) about once per month. These are C&D AGM UPS12-350MR batteries with a 10 year lifespan. They are swapped out for new every 12 months as a "precaution" and I have access to the "old" ones. Basically, I can get 80 of these batteries that are in like new condition every 12 months if I want.

My question is... If I put these in my conditioned basement on the racks and wire them up to an inverter charger... Is there an inverter charger or other device on the market that can be programmed to charge these batteries at night when my EV rates are 1.3 cents per KWh and then use the batteries during the day during peak rates. I know this as load shifting or peak shaving, but I'm not sure what the actual term is.

I don't NEED to do this, but I have the batteries and a desire to purchase solar equipment before the credit goes away -- If I can buy and use a couple of the components in the mean time to stick it to the electrical man, I would want to do that. When I have my solar friendly property, I would want to reuse as much of this infrastructure at the new place as possible -- Putting my existing home back to normal.

Basically, I would want to be on the grid AND charging the batteries at 11PM ($0.013 per KWh)... Then off the grid and on the batteries starting at 7AM to 2PM ($0.23 per KWH) . The period between 2PM and 11PM is 6 cents per KWh but I do not know if I can shift enough of my usage to allow the batteries to support 16 hours without going below 50%. I would think that if the batteries approached 50% during the 2 to 11 time frame, the system could just switch back to the grid and I'd live with 6 cents per KWh usage and the batteries would then start charging again at 11PM.

Does such an inverter/charger exist or will I need to cobble something together with relays to open and close the grid at certain times of the day and when the batteries reach certain voltages?

Many many thanks for any info you can provide.

Comments

  • solar_davesolar_dave Solar Expert Posts: 2,356 ✭✭✭✭
    I think you better look at the tax break again, the devices must be placed into service to technically qualify for the tax credit.

  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    I think you better look at the tax break again, the devices must be placed into service to technically qualify for the tax credit.

    Quite right.  And a battery/inverter system doesn't qualify anyway.  A battery and inverter do count when they are an integral part of a residential renewable energy system.   A battery/inverter system without solar, wind or hydro is not renewable energy system.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Forget about the UPS batteries. Trust me, I did the same thing you are thinking of doing several years back. It is not worth the hassle. You might even be able to find my thread on here from way back then.

    First off, those batteries are designed for FLOAT SERVICE regardless of the label on the stating "deep cycle" (if there even is one). Generally after a few deep "cycles" the batteries need to be replaced. That is why you see telcom batteries (and UPS batteries) being given away (or sold cheap) all the time. They have to replace them after a long power outage and/or after a couple of years of "standby use". And their claim of "10 years" is again in FLOAT SERVICE. Without any cycles. As soon as you cycle them, it cuts YEARS off their remaining float lifespan. That's why they get rid of them. If they "believed" the 10 year thing, there would be no reason to get rid of them even as a "precaution". 

    I was able to get 48, 12v UPS batteries, very similar to the ones you are talking about for FREE. They were in service for about 3 years, and only had been cycled a couple of times (literally) for short periods. I know this because I was the network Engineer at the hospital and did the original installation.

    I knew I was not expecting much, but I was at a point where I needed new batteries anyways and figured if I got a year out of them then that would allow me to save some $ for a good set.  And they were FREE!!  Well, long story short, they are such low AH ratings (and be sure those ratings are the 20ah rating, they might only be 8hr ratings) that you have to series/parallel a crap load of them to have any kind of usable bank. Now, you have so many parallel connections that they never charge/balance properly. Additionally, they are sealed batteries, so you cannot check the SG of them to see their condition. Voltage is not an accurate measurement.  So you never know the state of each individual battery. One bad battery/cell in the bank and it will screw up your entire charging of the rest of the bank (at best) and at worst can cause a thermal runaway condition causing an explosion and/or fire.

    In the UPS environment, they are basically "trickle charged" 24/7.  They are not designed to accept a whole bunch of current INTO them daily. If you look up the spec sheets on them you will see what I mean. Pay close attention to the "cycle lifespan" graphs.  The 10-years is float with no cycles, after 3 or 4 cycles to 50% it drops to 5 years and so on.

    Well, every couple of weeks, my bank would have diminished capacity. It would all look good on a voltage side when charging (and getting the proper specific voltage/currant to them was a chore also), but as soon as the sun went down, they would discharge quickly and unevenly and the voltage would drop. So every couple weeks I would test every battery with an old-school load tester (ony way you really can on sealed batteries) and pick out the bad batteries and replace them with the "spares".  This went on for months until I finally got so tired of testing them and moving them I just scrapped the whole bunch and bought a real set of deep cycles (Trojan T105-RE's at the time).

    I know what you are thinking, and again, "I" was "You" several years ago. You are prolly thinking what I did..."If I get a year i will be happy"...well, I guarantee it will be the most miserable year of your life. 

    And like the others said, you have to have the system (including the solar) IN SERVICE (running) by the end of 2016.


    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • RoddzillaRoddzilla Registered Users Posts: 2
    edited October 2015 #5
    Well crap. Thanks for the info jcheil. I, like you, am an engineer at the facility where these batteries are located. They rarely take the tech power load (power outages and monthly genset testing only) and only for about 15 seconds until the gensets spin up. I thought, "why recycle these every year when I can keep them and make a massive solar battery array." The system they come out of is an [email protected] 3ph which contains multiple strings of 80 batteries. We replace 2 strings every year for no real reason other than to make sure we have the freshest batteries we can. Our quarterly battery load tests have shown maybe under 10 bad batteries in the last 15 years.

    I've got extra racks and copper interconnect cables. I was planning on putting 2 racks and 80 batteries in my basement. I told the Mrs. I was thinking about doing this, but didn't exactly tell her how much floor space it would have really taken up.

    I've attached the spec sheets for the batteries and they didn't look that bad to me, but your experience has sufficiently spooked me out of wanting to trailer home 5,400 lbs of these puppies and learn the hard way.

    Also, to the other replies... Thanks for the install heads up. Yes, I will purchase the entire system and install it before dec 2016... The panels might have to be ground mounted (and not creating much power) for the first year or so as I'll need to be able to easily move them when I have the cabin ready. 

    Again, I can't thank you guys enough. 







  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Yeah those look almost exactly like the ones I tried to use. Except my UPS was from APC, not Liebert.

    Not sure where you are located, but here in FL you can usually get around $20 for an old battery of that size at the scrap yard.
    With 80 batteries, that's $1600 you could get.  $1600 will get you 6 Trojan L16RE-B 370ah 6v batteries delivered (here in central FL). That's a good start for a nice battery bank (you would need 8 for a 48v system which is the voltage you would want to be at for a full time off-grid place) that will last you 7-10 years and they are RE specific batteries (5 year warranty). I use them myself.  

    The other thing to realize is that "real" deep cycle batteries NEED to be "deep" cycled frequently to maintain good health.
    You'll hear about people who only discharge 10% each day and then have problems later on with diminished capacity.
    That's another reason why these batteries from UPS/telcom may only be a few years old but don't "work" well when you try to take them out of service and use them in a RE setting.

    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    And PS - Look at the ground mounts I built. They were rather inexpensive, adjustable and depending on how you put them into the ground, you could likely move them later on also.
    http://www.facebook.com/somewhatcrookedcamp

    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    edited October 2015 #8
    >The other thing to realize is that "real" deep cycle batteries NEED to be "deep" cycled frequently to maintain good health.

    Im not sure id go that far. The general rule is that the deeper the cycle depth, the shorter the cycle life. However the Ah life is a variable that may or may not be related to cycle life. In my studies of various cycle life curves overall cell amp hour life is about fixed, regardless of cycle depth. You might have fewer deep cycles but you get more amp hours out of it per cycle if that makes sense.

    Thats from a cycle life curve point of view. From a chemistry perspective, there are electrochemical processes that do occur at high states of charge, (positive grid corosion, negative plate depolarisation etc). Its my understanding that these affect AGM cells to a much higher degree, with their thinner plates, oxygen containment etc.

    Another factor to consider is charge efficiency. A study ive been quietly accumulating equipment to do, is to measure the charge efficiency of different types of batteries at different DOD regimes. Becasue the charge efficiency falls off, reducing to 0 with a fully charged battery, shallow cycles introduce a greater loss from battery cycling. We tend to not pay a heck of a lot of attention to this because when our banks are full or almost so, we dont care too much about it, becasue we know we are going to be tossing all the rest of the days solar away anyway. But with hybrid systems or those with agressive oppurtunity loads, charge efficincy needs factoring.

    I think your point is that one should try to use a particular battery the way it was designed to be used. Float service batteries for backup, deep cycle for cycling, industrial/motive for real deep cycling.

    Our general rule is 25% DOD daily cycles, and that works out for a number of reasons that ive discussed here before.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • mike95490mike95490 Solar Expert Posts: 8,653 ✭✭✭✭✭
    Well, there is a "Cycle Service" charge voltage (14.4v) listed, so maybe you can get a couple hundred cycles out of them.
    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 ,

  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    mike95490 said:
    Well, there is a "Cycle Service" charge voltage (14.4v) listed, so maybe you can get a couple hundred cycles out of them.

    Mine said the same thing and they were dead within 4-5 months.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    jcheil said:
    Forget about the UPS batteries. Trust me, I did the same thing you are thinking of doing several years back. It is not worth the hassle. You might even be able to find my thread on here from way back then.

    First off, those batteries are designed for FLOAT SERVICE regardless of the label on the stating "deep cycle" (if there even is one). Generally after a few deep "cycles" the batteries need to be replaced. 

    ... that you have to series/parallel a crap load of them to have any kind of usable bank.

    I disagree about the sealed UPS batteries.  I have a set in my APC that were used when I got them, I've had them for several years with multiple deep discharges, and they are still fine.  I do a full load test every 6-12 months.

    What ARE designed for float service are the telephone system backup batteries.

    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Thats a different planet to my (older) APC units. Two year battery changes, by 3 year, they are bulging so much i cant get them out. I do however use those cells in our electric fence unit, and that things hammers them, id say 50% DOD cycles every night, 75% DOD in winter. Get about 12-18 months out of each battery.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    techntrek said:
    jcheil said:
    Forget about the UPS batteries. Trust me, I did the same thing you are thinking of doing several years back. It is not worth the hassle. You might even be able to find my thread on here from way back then.

    First off, those batteries are designed for FLOAT SERVICE regardless of the label on the stating "deep cycle" (if there even is one). Generally after a few deep "cycles" the batteries need to be replaced. 

    ... that you have to series/parallel a crap load of them to have any kind of usable bank.

    I disagree about the sealed UPS batteries.  I have a set in my APC that were used when I got them, I've had them for several years with multiple deep discharges, and they are still fine.  I do a full load test every 6-12 months.

    What ARE designed for float service are the telephone system backup batteries.

    LOL, you really think there is a difference between a "telephone" backup and any other kind of "non-telephone" backup? They are ALL UPS's. They ALL (including my hospital's big one, the little one under my desk and all of yours) just sit around "FLOATING" until they need to be used for a power outage and after that they "CYCLE" back up to full charge. Therefore the manufacturers do not need to provide expensive batteries capable of "daily" cycles.

    But hey, your mileage may vary. These forums are about opinions and experiences.

    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    edited November 2015 #14
    The round (cylindrical with stacked flat plates) pure lead batteries that are sometimes used for Telco central office and other backup are, among other things, optimized for low internal resistance so that they can be used for high demand loads.
    Telco battery banks will also often have an "end cell" which is kept out of the main string but charged and is then switched into the series connection when the bank changes from being a regulator/filter at the float voltage to delivering the power requirements of the equipment.
    SMA SB 3000, old BP panels.
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