XW6048 semi off grid

yellowheadyellowhead Registered Users Posts: 17 ✭✭
First thanks to all for a most informative site.

I have an off grid home under construction that I need to get set up with power. Solar probably isn't a great option (too far north, narrow valley, too many trees) and wind and micro hydro are non-starters. I have a 3kw diesel genset and I'm also looking at pulling in a buried power cable from a service off the nearest power pole (2km away :cry: I won't get much power out of that at the far end but it should be good for at least 1kw and maybe more.

My intention is to go with an XW6048 and 8 Surrette S530s. The XW seems to be a perfect fit with both AC and generator inputs and a decent charger. I've read the XW docs and was really sold on the load shaving (AC2) and gen support (AC2) features but not totally clear how they worked in practice. So I was hoping someone could fill me in.

1. When the grid is up, assume I have [email protected] available at AC1 (from that long extension cord I mentioned above). I'll set AC1 to continuously load shave at this level. What I'm hoping is that for house loads << 1kw, the grid supplies the house loads with any excess going to charge the batteries (if required). Then as house load approaches 1kw battery charging backs off until the grid is supporting house loads only. Then as house load increases further, the inverter kicks in to support them up to a maximum of 6kw.

2. When the grid is down for a while and the inverter has run the batteries down, I'll use the automatic generator start to bring the generator online on AC2. I'll set AC2 to have gen support above 3kw. Then I'm hoping things will behave much as for AC1 load shave as above with the batteries being charged at low house loads and the inverter supporting during periods of high load.

Is this how it all works? Does anyone see any problems with this? This is still a paper project so I'm happy to be told that I'm doing it all wrong. Much easier to fix it on paper than once the kit is in the power shed ;)
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Comments

  • Ralph DayRalph Day Solar Expert Posts: 887 ✭✭✭✭
    Re: XW6048 semi off grid

    You'll have such voltage drop at that distance the XW will likely not be able to synch with it. Check the XW parameters for AC1 in, and calculate the voltage drop for 2km (you gotta be kidding) of cable. Might be better to upsize the generator to get full capability out of the XW and forget trying to get grid power unless it's in your yard.

    Ralph
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid

    That's the usual response I get :D

    However, I did do some homework and I've checked feasibility with both my local inspector and the electrician I'll probably hire to do (at least some of) the work. It goes like this:

    1. Pole service with 240V 15A circuit feeding a step up transformer (2.5:1 so 600V on the secondary).

    2. 6500 feet of 6/2 aluminum direct burial cable. Loop length 13000 feet. #6 AL is .648 ohm per foot. Loop resistance 8.5 ohm (more or less).

    3. Loop current 6A (per 2.5:1 step up), voltage drop 50V, so about 550V at the far end.

    4. An identical transformer at my power shed wired for step down this time. Should give me 220V at 15A. Looks like I can centre tap this

    I know I've ignored things like winding resistance in the transformers (but its probably negligible compared to the transmission line) and efficiency losses in the transformers (which will reduce the real current available at the far end). I'm also way over allowable voltage drop for the circuit per the NEC (3% or 5% depending on how you look at this).

    However, all my discussions suggest I'll get useful power out of this. At least 1kw and probably 2-3kw. At full load the efficiency looks to be about 80% which isn't too bad. Voltage drop and losses get better the lower the power draw.

    The numbers seem to add up but I'm more than happy to be proved wrong. I'd hate to bury 6500 feet of 6/2 to find I'd screwed up the math ...

    In case anyone is wondering about economics, my electrician has said he can get 6/2 AL for under a buck a foot. Pulling primary (i.e. overhead) high voltage looks to be $40K+. Solar could probably compete in the sunny part of the year but I don't think I could buy a solar array that would produce anywhere near 24kwh/day in the winter months at comparable cost.

    Cheers,

    Simon.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: XW6048 semi off grid

    24 Kwh / day? ? ? a watt saved is worth a lot of watts made....


    what conservation measures have you applied? CFLs, new fridge, new TV, etc etc??

    cheers,
    Eric
     
    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
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    I think your idea of the "reduced power" service and the XW Hybrid inverter + battery bank is a very interesting solution.

    I would double check with Xantrex support (and/or your local retailer--I am certainly no XW expert) to verify all of your assumptions--but I would think that it should work OK...

    I don't see any specific errors in logic that would say it cannot be done.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    westbranch wrote: »
    24 Kwh / day? ? ? a watt saved is worth a lot of watts made....


    what conservation measures have you applied? CFLs, new fridge, new TV, etc etc??

    cheers,
    Eric

    I totally agree. That isn't my expected daily usage; that's the most I could pull from the 'long extension cord' delivering 1kw peak. I am shooting for under 10kwh day but I realize even that is pretty greedy if you had to derive it all from solar. Taking the full amount the line could deliver probably wouldn't work well with load shaving anyway; you would never have time to get the batteries up to absorb voltage for any length of time.

    Note that I'm not saying I will never add some solar; I likely will as time and money allow. But a reasonably sized array/battery bank is probably not going to meet my needs more than 2/3 of the year. Running generator to make up the difference will not be cheap. Its hard to anticipate exactly how much it will cost but I'm guessing I'll pay back the cost of my line in under 10 years.

    Simon.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: XW6048 semi off grid

    Yhead, what will you be running that will create a 3 Kw load? heavy tools? 220V table saw? just trying to think this through. Can this surge be covered by the batteries with Grid ?

    Eric
     
    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
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    westbranch wrote: »
    Yhead, what will you be running that will create a 3 Kw load? heavy tools? 220V table saw? just trying to think this through. Can this surge be covered by the batteries with Grid ?

    Eric

    Hi Eric:

    Thanks for the feedback. My understanding of XW6049 load shave functionality on the AC1 input is that you can set a maximum current (say 4A in this case) that the inverter will allow to be pulled from the grid. If loads exceed this then the inverter switches from charging (if it was) to inverting to support the extra load demand.

    I don't have any specific 3kw loads. However, I will have an (efficient) electric fridge, a 120V 1/2hp well pump, a tankless water heater etc. etc. in addition to the usual kitchen appliances (not those with heating elements :) power tools and so on. None of these alone would exceed 3kw. But I can easily see enough of them coming on at once to exceed my grid power limit (whether that turns out to be 1, 2, or 3 kw). Without inverter support that would either trip a breaker or cause unacceptable voltage drop. With inverter support I can go up to 6kw by drawing on battery power for the duration of the higher load. After the load is removed, there will be 'spare' grid capacity with which to recharge the batteries at the next charging cycle.

    Make sense?

    Simon.
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: XW6048 semi off grid

    Before you put out the money just make sure you are complient to local codes. Without a neutral between transformers you might be at risk for lightning punching through primary to secondary of transformers. If code allows it, an autotransformer may be a better choice.

    The only concern I have with the XW is fast bounces on the line where it might release due to a quick 20 v dive on the AC1 when a sudden load appears.

    If you can manage to have the charging keep the AC1 loaded you may get away with it. It depends on how fast the XW will react to track a voltage dip.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: XW6048 semi off grid

    got it.. In my case it would have to be battery/PV supplied with gen backup. I plan on using the gen for heavy tools, with other loads to use up the spare while bulk charging.

    One trick is to wait till the CC has the batteries in Absorb (if recently used) and then run your heavy loads, that way the batteries are near full charge and will not be over depleted.

    Do you have to 'set ' the XW or can you let it determine it is not getting enough from the grid?

    +-5 Kw is a big surge load =~ 105 A @ 48 v, but that is another question...

    HTH

    Eric
     
    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
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: XW6048 semi off grid

    You set what you want the maximum AC1in draw is. How fast it reacts to load shaving is the question. If it is too slow the XW will likely release from grid.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    RCinFLA wrote: »
    You set what you want the maximum AC1in draw is. How fast it reacts to load shaving is the question. If it is too slow the XW will likely release from grid.

    That's a very good point. Based on my expected line resistance I think I can get to about 4800W from AC1 before the voltage will droop to the default for AC1 Lo Volt (106V). After that it will be case of what happens first. Either load shave will kick in and start supporting AC1 (in which case the load on AC1 will presumably fall back to that defined by the AC1 Load Shave Amps) or the inverter will go off grid to supply the load (and the load on the grid from AC1 will be removed).

    I'm hoping I can get away with the first case most if not all of the time. I'd guess starting large inductive loads (the well pump perhaps) would be the thing leading to the second case. Even then it doesn't look like it would be a show stopper. The XW would eventually reconnect to the grid and either drop out of invert mode or resume load shaving depending on the load at that time.

    At least that's how it looks from the documentation. Whether it actually works that way in practice is another matter :)

    Simon.
  • peterakopeterako Solar Expert Posts: 144 ✭✭
    Re: XW6048 semi off grid

    Keep in mind the cost for two transformers, cable, digging and installation.
    This sounds expensive.

    In my case i am 1KM away from the first power point and 2.5 KM from the first HV transformer. The power cable hookup for me wash around 16.000 Euro two years a go. So i went offgrid but installing on a way that in the futture it can be a battery backup on grid.

    Now on this moment the local energy company is updating the service the next months and i can hookup for around 1000 Euro:D
    I am think to do that and use night time metering After 22:00 until 8:00 it is 50% off the normal price.
    And i am thinking to run at night on Grid ( plus running at night the wash & dish washers ) and at day time on battery ( plus wind power ).

    p.s. i have seen this type off load sharing systems, not using a XW6048 but other manufactors the big problem is for astable adjustment. The problem is not only your use but also the other user on the network can drop your voltage.:grr

    Greetings from Greece8)
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    Remember too--his is in a deep/dark valley...

    Perhaps working directly with the Manufacturer (try contacting Jim/Crewzer directly via PM--he is busy in training right now but was hired to provide additional direct support for the XW product line among other things).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    peterako wrote: »
    Keep in mind the cost for two transformers, cable, digging and installation.
    This sounds expensive.

    In my case i am 1KM away from the first power point and 2.5 KM from the first HV transformer. The power cable hookup for me wash around 16.000 Euro two years a go. So i went offgrid but installing on a way that in the futture it can be a battery backup on grid.

    Now on this moment the local energy company is updating the service the next months and i can hookup for around 1000 Euro:D
    I am think to do that and use night time metering After 22:00 until 8:00 it is 50% off the normal price.
    And i am thinking to run at night on Grid ( plus running at night the wash & dish washers ) and at day time on battery ( plus wind power ).

    p.s. i have seen this type off load sharing systems, not using a XW6048 but other manufactors the big problem is for astable adjustment. The problem is not only your use but also the other user on the network can drop your voltage.:grr

    Greetings from Greece8)

    Lucky you :D If I could get hookup for 1000 euro I'd be all over it. The battery backup on grid approach is appealing I think.

    Costs for my long power cable are certainly a concern. The cable itself is reasonable, the transformers can be had second hand at a good price (couple of hundred bucks each), and the pole service is easy enough to figure. The big unknown is the trenching. I'm lucky in that the ground is pretty much level and the subsoil is 100% sand. Real easy to dig and no need for sand to bed the cable. I'm planning to do this myself.

    Greece, now that sounds like a good spot for a solar installation ;)

    Cheers,

    Simon.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    BB. wrote: »
    Remember too--his is in a deep/dark valley...

    Perhaps working directly with the Manufacturer (try contacting Jim/Crewzer directly via PM--he is busy in training right now but was hired to provide additional direct support for the XW product line among other things).

    -Bill

    Thanks. I'll do that.

    Simon.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: XW6048 semi off grid

    This is from another thread, but in a sort of similar situation I did this. By the way on the XW the lowest AC1 input you can set for is 5 amps at 240vac. But if you just avoid the XW all together and use external chargers from the "long extension cord" you could get away with a much wider input range to the chargers and wouldn’t have to worry about motor starts since the chargers will just do their thing. But even if you don’t go the external charger route the XW will do what you are suggesting and draw a constant load of 5 amps until the batteries are changed and no load is present. You might drop AC1 on a motor start, but it will just re-connect after it settles down.
    I had our two SW2512 inverters and battery bank at the site. They wanted close to $1000 to run a temporary feed for construction so I ran a line from my parents about 1200 feet away. I didn't think it would start a motor, I did try our air compressor, no luck starting it on the cord itself. I then used an iota charger feeding the batteries and let the inverters do their thing. They could start compressors, table saws just fine and the charger pretty much kept up. Once in a while the batteries would drop to maybe 95% when they were doing a lot of cutting and compressor running, then once they stopped the iota would catch back up.

    I would suggest something like #8 or #6 at 240v and at the "house" end put two iota chargers on the 240 (120 on each side) and connect them to your battery bank and your good to go. The iota chargers will run fine down to about 90v and then the output falls off after that. Your inverter will do the regulating and balance out on the load.
    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
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    The method with Battery chargers to battery to off-grid inverter will work fine too...

    My only caveat is that you have another ~20% loss at the battery chargers for all of your loads--vs 10-20% charging losses only when you draw above 1kW at the home.

    The XW charger is power factor corrected--so you have that 0.6-0.8 current derating (VA, KVA, KVAR) that you get with non-power factor corrected typical efficiency battery chargers.
    • 5 amps * 0.6 PF * 0.8 efficiency * 220 vac = 528 watts usable at the battery
    The XW in the same setup with PF=1 and a 90% efficient charge controller (as I remember):
    • 5 amps * 1.0 PF * 0.9 efficiency * 220 vac = 990 watts usable at the battery
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: XW6048 semi off grid

    Good catch, this is why we like to keep Bill around :)
    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
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    Brock wrote: »
    This is from another thread, but in a sort of similar situation I did this. By the way on the XW the lowest AC1 input you can set for is 5 amps at 240vac. But if you just avoid the XW all together and use external chargers from the "long extension cord" you could get away with a much wider input range to the chargers and wouldn’t have to worry about motor starts since the chargers will just do their thing. But even if you don’t go the external charger route the XW will do what you are suggesting and draw a constant load of 5 amps until the batteries are changed and no load is present. You might drop AC1 on a motor start, but it will just re-connect after it settles down.

    Thanks for that. I'd been seriously considering the standalone charger route in my earlier investigations based on Outback equipment (due partly to the absence of load shave/gen support but also the poor power factor of the FX series charger). However, when I discovered the XW I thought I'd hit gold. And I may still have :D An occasional AC1 drop on starting a big load really wouldn't be an issue if the inverter handles it smoothly and eventually reconnects.

    If all else fails I still have the charger route as backup. I'd use a surplus switch mode power supply fed into an XW SCC. It's not a cheap solution (mainly due the the SCC) but it is reasonably efficient, the power supply is power factor corrected, and the charge controller takes care of battery management.

    Cheers,

    Simon.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    BB. wrote: »
    The method with Battery chargers to battery to off-grid inverter will work fine too...

    My only caveat is that you have another ~20% loss at the battery chargers for all of your loads--vs 10-20% charging losses only when you draw above 1kW at the home.

    The XW charger is power factor corrected--so you have that 0.6-0.8 current derating (VA, KVA, KVAR) that you get with non-power factor corrected typical efficiency battery chargers.
    • 5 amps * 0.6 PF * 0.8 efficiency * 220 vac = 528 watts usable at the battery
    The XW in the same setup with PF=1 and a 90% efficient charge controller (as I remember):
    • 5 amps * 1.0 PF * 0.9 efficiency * 220 vac = 990 watts usable at the battery
    -Bill

    Good point. Actually, I think the IOTA chargers mentioned are power factor corrected. But regardless it is going to be way more efficient to use that first kw directly to power low level house loads directly and only supplement it from the inverter if required than convert that kw to DC for battery charging and then convert it back to AC to run house loads. That was why I was so excited when I discovered the XW and load shaving ...

    Thanks,

    Simon.
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    I am not positive--but every time I look at the Iota Power Supply specifications, I don't think they are power factor corrected (from my experience--the specifications don't add up to what I would expect from a PFC device)... If I had to guess, perhaps the supplies are in the 0.65-0.70 PF range.

    If somebody has an Iota and a Kill-a-Watt meter (what--there is somebody here for more than 5 day that does not have a Kill-a-Watt meter on order :confused:)--perhaps they can do a quick measurement and confirm or not...

    If PFC (Power Factor Correction) is important to you (and I would highly recommend it)--then I would call Iota support and confirm.

    On paper, the XW charger looks very nice and I hope that it works well for your setup.

    My one suggestion is for "critical devices", such as desk top computers, I would get a small UPS and buffer your XW power output... I don't know--but switch over of any "standby" type UPS can cause desktop computers to crash (even the "real ups's that I have worked with--something like 1 in 10 "real" power failures will seem to reboot a desktop computer).

    If you can use laptops with their own batteries--two problems solved--less power used and internal continuous conversion UPS (DC Battery Bus) with no external UPS.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: XW6048 semi off grid

    I believe the resistance number for #6 alum is .648 per thousand feet. Your results are correct however.
    If it was me, I'd spend that kind of dough on silicon instead of aluminum, multiply it with whatever incentives you have available and conserve however I needed to instead of just propagating the grid system.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    BB. wrote: »
    I am not positive--but every time I look at the Iota Power Supply specifications, I don't think they are power factor corrected (from my experience--the specifications don't add up to what I would expect from a PFC device)... If I had to guess, perhaps the supplies are in the 0.65-0.70 PF range.

    If somebody has an Iota and a Kill-a-Watt meter (what--there is somebody here for more than 5 day that does not have a Kill-a-Watt meter on order :confused:)--perhaps they can do a quick measurement and confirm or not...

    If PFC (Power Factor Correction) is important to you (and I would highly recommend it)--then I would call Iota support and confirm.

    On paper, the XW charger looks very nice and I hope that it works well for your setup.

    My one suggestion is for "critical devices", such as desk top computers, I would get a small UPS and buffer your XW power output... I don't know--but switch over of any "standby" type UPS can cause desktop computers to crash (even the "real ups's that I have worked with--something like 1 in 10 "real" power failures will seem to reboot a desktop computer).

    If you can use laptops with their own batteries--two problems solved--less power used and internal continuous conversion UPS (DC Battery Bus) with no external UPS.

    -Bill

    Oops, I think you are right about the IOTAs :blush: I had it in my head that they were PFC but looking at the specs again perhaps not ...

    If I need to go down the charger route I'll likely use a charge controller fed by a (PFC) DC power supply. Might cost a bit more up front but it would allow the easy addition of solar.

    PFC is definitely important. Low PF would result in increased current flow in the cable to deliver the same power which translates to higher power losses.

    I like the idea of a separate low power inverter for sensitive loads. Computing will be laptop based but things like the electronics in the tankless heater might benefit. I guess I'll have to try it and see ...

    Thanks,

    Simon.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    solarix wrote: »
    I believe the resistance number for #6 alum is .648 per thousand feet. Your results are correct however.
    If it was me, I'd spend that kind of dough on silicon instead of aluminum, multiply it with whatever incentives you have available and conserve however I needed to instead of just propagating the grid system.

    Sorry about the resistance typo. Glad the math still made sense though.

    I'd love to go solar but I don't think the numbers add up. There are no significant incentives that I am aware of for solar PV (BC, Canada). The location is northerly (52 53 N) in a relatively narrow mountain valley (the Rocky Mountain trench) and heavily treed. The topography and mountain weather alone would make solar a challenge in the winter. The trees make it even worse.

    There are a few off grid houses in the valley and all that I know of have to rely on running generator in the winter. Grid power is currently cheap (6c/kwh) and largely hydroelectric. It doesn't take many kwh generated by burning diesel at 50c+/kwh to completely offset the 'free' power I would get from a PV array (never mind the CO2 emitted burning diesel which whether you accept climate change or not seems likely to get get more expensive in the future).

    So unfortunately, propagating the grid seems to be the most practical way of providing my power needs. Power conservation certainly helps but it has limits (depending on how spartan you want to be :D I estimate my base load (efficient electric fridge and freezer, ventilation system, hydronic circulation pumps etc) to be ~3kwh/day. Probably a bit less in the summer (no need for ventilation and heating) but that doesn't really help. Carrying just that in the winter would probably require ~3kw of solar and a much larger battery bank than my proposed 400Ah. That seems likely to cost me a lot more than burying cable.

    If I'm missing something here someone please shout. I'm pretty new to all this and have lots to learn ...

    Cheers,

    Simon.
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid

    Spoke to Xantrex tech. support about this. In case anyone else is looking at a similar application I thought I'd post what I learned here.

    Load shaving as currently implemented won't do quite what I want. Thats because during the load shave window (which is continuous in this case) the charger is disabled. This is true even if the house load is less than that defined by load shave amps i.e. 'spare' capacity on AC1 will not be used to charge the batteries.

    I am told that this will be fixed in the next firmware release although no ETA was available.

    Luckily, using gen support on AC2 behaves exactly as I want so there is a workaround in the short term.

    Simon.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: XW6048 semi off grid

    Just to keep this straight in an old mind....

    assume gen = 1 Kw , Load = 3 Kw

    on AC1
    the unit will provide 3 Kw, 1 Kw coming from the grid, the rest (2 Kw) from batteries,
    BUT when load is off no battery charging occurs

    On AC2 (gen)
    you get 1 kw from the gen and 2 Kw from the batteries
    AND battery charging when load is < 1 Kw (gen)

    Did I describe it correctly?

    Eric
     
    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
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    westbranch wrote: »
    Just to keep this straight in an old mind....

    assume gen = 1 Kw , Load = 3 Kw

    on AC1
    the unit will provide 3 Kw, 1 Kw coming from the grid, the rest (2 Kw) from batteries,
    BUT when load is off no battery charging occurs

    On AC2 (gen)
    you get 1 kw from the gen and 2 Kw from the batteries
    AND battery charging when load is < 1 Kw (gen)

    Did I describe it correctly?

    Eric

    Thats it. You'd think using any 'spare' capacity on either AC1 or AC2 to charge the batteries when the load is under the programmed limit would make sense. The inverter isn't running in either case so there is no reason for the charger to be disabled (I suspect the way the hardware is designed you can't charge and invert at the same time). And thats the way it appears to work on AC2. For reasons unknown it looks like the charger is disabled during the load shave window on AC1 (as opposed to just when the XW is actually load shaving). Sounds like I'm not the first to suggest this might not be ideal since a fix is apparently in the works ...

    Simon.
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    Probably just an engineering/marketing assumption... Most people have virtually unlimited grid power--so there was never any thought to the issue of load shaving+charging. It probably also raises issues with back feeding the grid in GT Mode and solar panels (high resistance of a grid feed could cause Grid Faults unless they install and test that whole function too).

    It is nice to hear that they are responsive to needs though--I hope that they can roll that function out in the near future for your installation.

    It sounds like you are on a bit of an issue with a "on the small size" battery bank with a limited charging capability of your AC Mains... If you ever plan on >4kW surge support--you want a larger battery bank (probably 600 AH minimum).

    However, if you size for a larger bank, you really don't have enough AC power to hit 5% of the Bank's AH capacity (sort of important for equalization--especially for flooded cell).

    If you want both (>4 kW and > 400 AH baank)--you may end up having to excersize a your genset every few months (+/-) if your flooded cell batteries need equalizing... (not sure about this--a lot has to do with how deep/many times you cycle the bank because of your AC mains limitations).

    Probably talk with your battery supplier/engineer to see what their recommendations are based on your system use.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • yellowheadyellowhead Registered Users Posts: 17 ✭✭
    Re: XW6048 semi off grid
    BB. wrote: »
    Probably just an engineering/marketing assumption... Most people have virtually unlimited grid power--so there was never any thought to the issue of load shaving+charging. It probably also raises issues with back feeding the grid in GT Mode and solar panels (high resistance of a grid feed could cause Grid Faults unless they install and test that whole function too).

    It is nice to hear that they are responsive to needs though--I hope that they can roll that function out in the near future for your installation.

    It sounds like you are on a bit of an issue with a "on the small size" battery bank with a limited charging capability of your AC Mains... If you ever plan on >4kW surge support--you want a larger battery bank (probably 600 AH minimum).

    However, if you size for a larger bank, you really don't have enough AC power to hit 5% of the Bank's AH capacity (sort of important for equalization--especially for flooded cell).

    If you want both (>4 kW and > 400 AH baank)--you may end up having to excersize a your genset every few months (+/-) if your flooded cell batteries need equalizing... (not sure about this--a lot has to do with how deep/many times you cycle the bank because of your AC mains limitations).

    Probably talk with your battery supplier/engineer to see what their recommendations are based on your system use.

    -Bill

    I'm guessing I'll actually have a fair bit more than 1kw to play with. This is just my worst case assumption in case the inspector is really sticky about voltage drop. However I suspect the real limit will be a 15A breaker in the pole service panel. Allowing for some losses that should provide nearly 3kw albeit at closer to 8% voltage drop. That's still quite acceptable from a functionality/safety point of view (if not strictly code compliant ;)

    If this is what I have then I'll probably set load shave/gen support at closer to 2.5kw. I'm not sure how much inverter boost I can expect from a 400Ah battery (it looks like you are suggesting no more than 3kw) but I think 5-6kw is a limit I can live with.

    The higher power would also be available for battery charging. The recommended max. charge current for the S530 is about 45A which is in the ball park of what AC1 could provide with a low house load (say overnight). I guess I'll have to wait and see how well all my assumptions hold in practice ...

    Cheers,

    Simon.
  • BB.BB. Super Moderators, Administrators Posts: 29,523 admin
    Re: XW6048 semi off grid

    Simon,

    I think what you are doing is cool! :D (yea--I am an engineer, want to make something of it? :p;))

    If the XW AC2/AC1 works well with your long power run--I think that this will be popular with the folks that are at the edges of the grid.

    Of course--there is always that guy which will have lots of hard won knowledge from being first.

    Best of luck and skill.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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