XW hybrid - grid tied w/battery - does this work?

newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
The property currently has a 100A federal pacific panel for the main service.

Does this work?

Replace the main service panel with a small 200A panel with a 100A main disconnect and then just 2 60 amp dbl pole breakers each going to an XW4024 inverter, then having a 125A subpanel fed by two 60A dpl pole breakers - one from each inverter - and then put every single circuit from the house in that subpanel.

Thus, the entire house is backed up by the batteries? And, when the inverter is off there is still the same 100A available that they have now?

If they wanted to add circuits in the future there would be room in the 200amp panel for non-backed up loads or they could shuffle things around if they wanted to at that time (they don't anticipate adding anything).

Comments

  • dsp3930dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Typically, you only battery back up your critical loads on the sub-panel. To back up the "average" grid connected home with all electric doodads ablazin' at a conservative estimate of 25kwh per day, you would need batteries capable of delivering at least 50kwh to this home. (to allow for a 50% depth of discarge) This roughly equates to _at least_ a 1000ah battery backup @ 48v or 2000ah @ 24v.

    The beauty of the Xantrex units are that you can power your sub-panel (via your load line) and main panel (via selling back to the grid via AC1) all the time. Then in a power outage situation, you can still power your critical loads just off the sub-panel. You don't want to be fidding with priority in that situation.


    Note: You can still have regular circuits with breakers on that main panel busbar. The 240A limit (NEC 1.2 x 200A busbar rating) only applies to feeds into the busbar, not going out.
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Yeah, I understand and explained that they will either be able to live normally for a very short time during an outage OR back up critical loads for a possibly extended period.

    They seem more concerned about short term outages and seem to want to fiddle around with priority.

    I just want to be able to give them the options anyway. I'll definitely go over the circuits and suggest that some of them go into the main service panel and just the ones they really want go in the inverter output panel.

    I was concerned with how much power they get to the inverter output panel with this design - 60A or 120A (60 from each - both dbl pole). I talked to customer service at Xantrex (Schneider) and it seems like it is 120A.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    The 60 amps is pass through, not back up ability of the XW-6048.

    25 amps @ 240V = 6kw is your maximum steady state load and you have to allow for start-up surges that motor loads present. If your going to have mixed loads, the most imbalance you can have is 75%, so you could pull a maximum of 37 amps from one 120V phase ( 4500 watts ) but the total can't exceed 6kW steady state

    Its bad design to leave it to the home owner to select circuits, backup only the most critical loads, other wise there backup will be measured in minutes as the home owners will likely only notice an issue when the battery bank fails from being overloaded
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Ok, I am confused. You already have a 100 amp panel. Why not just take two 60 amp double pole feeds from that panel to the inverters? The issue I see is the output side of the inverters shouldn’t be mixed back together unless the inverters are sinc'ed.

    Why not just go with a XW6048. Having dual XW4024's is going to have a HUGE battery bank at 24v the wires will have to be huge. A 48v bank would be more manageable on both the solar / charge controller or input side as well as the inverter side.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    Brock wrote: »
    Ok, I am confused. You already have a 100 amp panel. Why not just take two 60 amp double pole feeds from that panel to the inverters? The issue I see is the output side of the inverters shouldn’t be mixed back together unless the inverters are sinc'ed.

    Violates the 120% rule. 100amp panel can be fed up to 120% of it's rating = 120A. That would be 100amp from utility + 60amp from inverters = 160amp.
    Brock wrote: »
    Why not just go with a XW6048. Having dual XW4024's is going to have a HUGE battery bank at 24v the wires will have to be huge. A 48v bank would be more manageable on both the solar / charge controller or input side as well as the inverter side.

    I'm looking at the price difference for an XW4548. That's probably what I'll do. The PV array is too big for one 6048. The price on my distributor's list (before discount) is $350 more for the 4548 and the 6048 is another $900 above that.
  • mike95490mike95490 Solar Expert Posts: 9,571 ✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    newenergy wrote: »
    The PV array is too big for one 6048.

    I did not know that the 6048 had a solar charge controller. I just bought one of the morningstar 60A MPPT's to go with mine. The 6048 has a 240VAC input for it's battery charger.
    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 ,

  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    The street price difference is 50-100 dollars between the XW-40** and the XW-6048

    As Mike points out, you still need your charge controllers and they feed the battery bank. The XW has nothing to do with the PV unless you trying to go Grid-Tie and then you have the 6Kw+ AC limit. This in most conditions is about a 7-8kw DC of PV in a GT setup once you figure in the panel, charge controller and inverter losses
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    the street price difference is 50-100 dollars between the XW-40** and the XW-6048

    As Mike points out, you still need you charge controllers and they feed the battery bank. The XW has nothing to do with the PV unless you trying to go Grid-Tie and then you have the 6Kw+ AC limit. This an do in most conditions about a 7-8kw GT setup when you figure in the panel, charge controller and inverter losses

    I saw on one site the price difference was pretty small, $110, but at my distributor the listed price diff. is over $1k and I'm getting a better price on the 4024 from my distributor anyway. As I mentioned, I might end up getting the 4548.

    It is a grid tied system with a battery backup, and I was expecting to get the charge controllers.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    There are many places to get the XW-6048 for 2900.00 , even more at 3K .. list price is meaningless ... 24V is insane at these current.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    newenergy wrote: »
    Violates the 120% rule. 100amp panel can be fed up to 120% of it's rating = 120A. That would be 100amp from utility + 60amp from inverters = 160amp.

    DOH, yes, when I first started typing I was thinking a single XW4024.

    What is the size of the array?
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    There are many places to get the XW-6048 for 2900.00 , even more at 3K .. list price is meaningless ... 24V is insane at these current.

    The price diff is down to $300. I'll try to get a price on the 6048 as well as the 4548. My usual distributor is having a conference now and they are hard to get a hold of.
    Brock wrote: »
    DOH, yes, when I first started typing I was thinking a single XW4024.

    What is the size of the array?

    36 Evergreen 210s.
  • dsp3930dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    A few other thoughts ...

    With two 4024s, you will incur the following extra charges/issues you might not be thinking about: 8kw/16kw surge

    Larger battery cables due to higher amperage requirements on the batt bank.
    2x the #6 hookup wire and 2x extra 60A breakers
    3x the horizonal space required (PDP + Unit 1 + Unit 2)
    1x Xantrex Connection Kit
    1x Xanrex Power Dist. Panel
    1x SCP
    2x MPPT60-SCC
    4x Watthour meters (If doing REC credits, etc, you will likely need a meter on each of the 60 amp feeds from the main panel and on the 60 amp feeds to the sub-panels.)
    2x standby consumption on battery power overnight.
    2x the shipping



    With one XW6048: 6kw/12kw surge
    1/3 the space with a Midnite Power Dist. Panel (Also less $$$ than the Xantrex one)
    -or-
    2/3 the space with a Xantrex PDP
    1x SCP
    2x MPPT60-SCC
    2x Watthour meters (If doing REC credits, etc, you will likely need a meter on the 60 amp feed from the main panel and on the sub-panel.)
    1x the shipping
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    I'm definitely sold on 48v, so that would be 2 4548s. So, that should take care of the battery cable issues. The 4548 vs. the 4024 basically pays for itself anyway by being more efficient and thus getting a bigger rebate.

    The array size is fixed - the customer is wants to zero their bill and this basically does that and also basically fills their entire available roof space. If one XW6048 would work that would be great, but in this case (grid tied battery back up - 36 evergreen 210s) it doesn't, does it?
  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    A 7560 watt array is about the limit of a XW6048, they do about 6400 watts AC , so figure 14% between the charge controller, inverter efficiency and wire losses and your looking a ~7400 watts DC.

    Panels rarely put out STC power, Panels have to have perfect sun angle, very cold air temps ( probably 30F or lower ) or the short busts of edge of cloud events.

    One nice thing you have here is the battery bank can handle these burst even if the XW can't sell every single watt and its storage will allow it to be sold a few minutes later.

    With a system this large your going to need 600-800ah of battery's just for the Gridtie to work well, as the ripple current becomes a big issue and if the battery bank is to small the charge controller will get messed up and stop tracking a high power levels

    You haven't mentioned how many charge controllers you will need ( 3 60 amp controller ), Id recommend the XW-Mppt or the MorningStar Mppt and your battery bank as I mentioned will need to be a MINIMUM of 600ah @ 48V, bigger is better
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    I really appreciate all your help on this. Thanks.


    The array is going to have 12 modules (Evergreen ES-210) facing a bit south of west and 24 modules facing a bit east of south.

    So, it really should never produce more than about 6000 Watts total.

    So, it should be good on one XW6048, right? That is with 3 XW solar charge controllers - 3 strings of 4 modules for each.

    And you can use the Xantrex Power Distribution panel to connect the 3 charge controllers, right?


    Now the battery bank is going to be 48 V, but is going to be considerably smaller than we are talking about. The batteries are going to be some new fancy lithium batteries made by Ojai Energy Systems. The customer is very set on this. The manufacturer insists that the size of the battery array won't be a problem because their management hardware/software and the fact that the batteries can charge and discharge faster than conventional batteries.
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: XW hybrid - grid tied w/battery - does this work?

    Using the California PTC ratings, 7,560 watts of solar panels will produce about 6,480 watts on a pure GT system...

    For two reasons, that will not be an issue for you. First, the MPPT Charge Controllers (Xantrex XW MPPT 60 Amp or equivalent) will charge the battery correctly even if there is more solar power than the XW Hybrid Inverter can feed back in to the grid.

    Second, the additional losses of a Hybrid Battery System will probably consume that few hundred "extra watts" that are (at least on my system in a temperate climate) only produces that maximum amount a couple times a year for a short time anyway...

    About their lithium battery array--A small bank will only give them a few hours of backup power before the backup generator needs to be cranked up (depending on their loads and the actual battery bank size, of course)--That is OK with them?

    Also, is the battery bank going to be placed outside the home (dedicated shed) as lithium battery failures can be pretty energetic? (reduce smoke/fire damage possibilities to home--although, there are supposed to be safer Lithium technologies--I have not studied them closely to know the risks/rewards for uses like this).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Batteries are outside and in a very rugged case. They are mounted on the wall.

    The array being divided into two orientations should really seal the deal on not producing too much power (wasting it) as well, right?

    There is no generator. I did a proposal with one, instead of batteries, but they want the batteries. They understand it's not much backup and won't last long at all unless they really restrict their usage.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    new,

    The large array w/ three CC's shouldn't be a problem for the inverter. You can set the XW's GRID menu "Sell Amps" to 25 A (240 Vac x 25 Aac = 6,000 VA), and the inverter won't sell more than 6 kW.

    The array configuration causes me some concern. The STC Vmp spec for four ES-210's in series is 74.8 V. Assuming a 20% voltage loss due to high cell temperature and an ~4 V loss in the wiring and charge controller, the max charge voltage to the battery bank may be limited to ~56 Vdc. Is this high enough to charge the battery bank?

    Also, does this system require a permit for the design and installation, and will it be inspected per local and/or NEC requirements? If so, you may wish to discuss these issues with the local AHJ (inspector) before going too far down this road.

    Finally, as noted, it's likely that the system will rarely -- if ever -- operate at full power specification. No matter. NEC Article 690 assumes the system will continuously operate at spec and beyond, and the permitting- and inspection process will likely be based on NEC requirements, and not "usual" conditions.

    Regards,
    Jim / crewzer
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Crewser, thanks.

    The battery manufacturer said the configuration is fine and it works with the Xantrex XW string sizing software. And if I'm doing the math right, the Evergreens don't lose 20% until they are 178 degrees F. They shouldn't get that hot - it's a warm area of Los Angeles, but not Las Vegas or Pheonix kind of hot. They will also be off the roof at least 6" or 7" for ventilation.

    As far as the NEC goes, the system should comply with all wire sizing, overcurrent protection and grounding requirements. The only thing code-wise that I think could affect the inverter rating here (and the inspectors would really never get into this) is following the inverter manufacturer's instructions, so as not to violate the listing. So far, I think everything is ok on that end.

    I could end up committing some money before everything is approved by the city, but I never do any part of the installation before that happens, and I would likely be able to redesign to meet the city requirements - or worst case recoup most of the money.

    Not that this system will ever produce more than the XW can sell, but what happens if the batteries are fully charged and the PV array is producing more than the 6000 watts? Can it safely dissipate a little extra?
  • jeffkrusejeffkruse Solar Expert Posts: 205 ✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?

    Can the XW CC be set for Li batteries?:confused:
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: XW hybrid - grid tied w/battery - does this work?

    Solar panels can be "turned off" and not have any problem (when panels have no load or are turned off, they just go to Voc -- voltage open circuit)... That is what a PWM/MPPT charge controller does when it does need 100% energy anymore--they just turn on and off to limit power flow to the battery bank.

    It is Wind Turbines and Water Turbines that (typically) over speed if they are not continuously loaded--so they need a dump load (typically placed on the battery using a dump controller) to absorb any excess power generated that the battery/loads cannot use directly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • newenergynewenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    jeffkruse wrote: »
    Can the XW CC be set for Li batteries?:confused:

    The battery manufacturer builds each system to order and they say they have no problem with the Xantrex XW. The manufacturer is local and will hopefully be available for any necessary tech support. They have been able to answer questions so far.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: XW hybrid - grid tied w/battery - does this work?
    the Evergreens don't lose 20% until they are 178 degrees F.
    Perhaps, but they’ll lose something along the way. The problem is that the temp derating is based on module cell temp, not ambient temp. The modules may operate at 25 C to 35 C above ambient, so if ambient is 30 C (86 F), the modules may operate at ~60 C (140 F) or higher.

    Using Evergreen specs, I calculated a 15% drop in STC Vmp for a cell temp of 60 C. That would put array Vmp at 63.6, and, allowing for an ~4 V drop in the wiring and CC, that would put the end-of-bulk stage charging voltage at 60 V.

    I’m not familiar with Li battery charging requirements. However, 60 V is just enough to charge an AGM battery bank, and, IMHO, it’s not enough to push an FLA battery bank to EQ target voltage.
    Not that this system will ever produce more than the XW can sell, but what happens if the batteries are fully charged and the PV array is producing more than the 6000 watts? Can it safely dissipate a little extra?
    The CC will limit array production to whatever power can be distributed. If the batteries are full and the XW sell limit is 25 A, then the CC’s will limit production to ~6 kW.

    Note that the XW6048’s official minimum lead-acid battery bank size is 100 Ah. I really don’t know if the XW chargers (inside the 6048 or the MPPT-CC) are adaptable to Li batteries.

    HTH,
    Jim / crewzer
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: XW hybrid - grid tied w/battery - does this work?

    Neweergy,

    I would add my voice to ensure that you are not left hanging if the battery vendor points at you for not providing the correct charge controller/configuration and Xantrex points at you for connecting a non-supported battery technology to their Charge Controllers and Inverters...

    And the customer is calling you up because you did exactly what they asked for, are local, and the system is not working as they hoped...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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