Grid Interactive question

I have 1850 watts of solar panels and a Xantrex xw solar charge controller running 24 volts. I would like to get an inverter that can feed my house the power that it needs during the day without using the grid, unless there is more demand than the output of the panels. I want any extra power to be charging my batteries, not grid tying. I have a smart meter that wont turn backwards. So I loose any power that is feeding back into the grid. As the sun sets , I would like the batteries to supply the house loads until it drops to a low voltage setting. Then the grid will supply all house loads for the rest of the night, until the morning where the cycle starts again. What kind of inverter, if any, will do what I am asking? I am looking at 1500 watts of new panels and 48 volt battery pack. I just want to make sure that I get the right inverter and then I will match the other components to it.

Thanks

Comments

  • SkiDoo55SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Grid Interactive question

    Conext XW 4024 would be a match that will do what you are asking and it will talk to the MPPT charger would guess you have a MPPT60-150?? If so when ZanBus'd together Inverter will only use surplus solar for grid support and let the charger, charge the battery bank. Best to also get the Conext ComBox for programming the inverter and your charger.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • pleppikpleppik Solar Expert Posts: 62 ✭✭✭✭
    Re: Grid Interactive question
    Marty wrote: »
    I have 1850 watts of solar panels and a Xantrex xw solar charge controller running 24 volts. I would like to get an inverter that can feed my house the power that it needs during the day without using the grid, unless there is more demand than the output of the panels. I want any extra power to be charging my batteries, not grid tying. I have a smart meter that wont turn backwards. So I loose any power that is feeding back into the grid. As the sun sets , I would like the batteries to supply the house loads until it drops to a low voltage setting. Then the grid will supply all house loads for the rest of the night, until the morning where the cycle starts again. What kind of inverter, if any, will do what I am asking? I am looking at 1500 watts of new panels and 48 volt battery pack. I just want to make sure that I get the right inverter and then I will match the other components to it.

    Thanks

    You may want to think about whether this is really the best option. I am not an expert, but I understand that by the time you do a complete life-cycle analysis of battery storage, even the most cost-effective batteries will still cost you around $0.50/kWh.

    Unless your power company charges you more than that, you may be better off just giving that excess solar back to the grid for free than trying to store it in batteries.

    A factor of ten drop in battery prices will be necessary to make local storage worthwhile. That's one of those game changing technology breakthroughs everyone is hoping for but which hasn't arrived yet.
  • MartyMarty Registered Users Posts: 3
    Re: Grid Interactive question

    Thanks for the input, the xw inverters is what I was looking at, but I couldn't tell how to program it to not go over what the house was pulling. If I stopped it from selling would that stop it from going over what the house is pulling? Thanks again
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Grid Interactive question

    I don't know how to tell you to test it, but some smart meters will register any current coming into or out of the buss as a draw against the utility. What that means you'll be paying the Utility for all you produce unless you disconnect the Mains. I guess you could call the Utility to see if yours is that way. It happened to me and many others that have turned on their Grid-tie systems before the Utility changed the regular meter to a net meter.
  • MartyMarty Registered Users Posts: 3
    Re: Grid Interactive question

    I can check my smart meter for hour to hour readings the next day. Right now I'm running two cheap 500 watt grid tie inverters and I flat line my readings from 10 am to 3 in the afternoon until I plug in my chevy volt. I will talk to my local Schneiders guy and see if he knows if the XW will work.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Grid Interactive question
    Marty wrote: »
    I can check my smart meter for hour to hour readings the next day. Right now I'm running two cheap 500 watt grid tie inverters and I flat line my readings from 10 am to 3 in the afternoon until I plug in my chevy volt. I will talk to my local Schneiders guy and see if he knows if the XW will work.
    Well, it doesn't sound like your meter does. Of course you can set a sub panel and separate some of the circuits and run Inverter as a grid supported back up with the sell shut off. The Outback G series has a HBX mode where you can do it. When the sun is out and the battery is charged it'll use battery till it falls to the level that support is needed.
  • SkiDoo55SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Grid Interactive question
    Marty wrote: »
    Thanks for the input, the xw inverters is what I was looking at, but I couldn't tell how to program it to not go over what the house was pulling. If I stopped it from selling would that stop it from going over what the house is pulling? Thanks again

    From what I have read on it, in the process of purchase and installing system, as backup mainly but will let it support loads on one of my sub panels it will attempt to support the loads and "zero" grid consumption. Settings would be "Grid Support ON/ Sell OFF". With it connected to a XW MPPT60–150 Charge controller it will extract as much surplus power to support the loads. The charge controller will use what power it needs as priority to charge battery bank. Rest of demand will come from grid. Then it will draw from batteries until the low voltage set point for grid support is reached, then loads will be from grid. In the morning the cycle starts over again.

    you can download the user and install manuals from NAWS (Sponsor) Store site.

    If you use a generator for backup it will support the generator in same fashion. If loads are below setting for gen size then charger in XW inverter will take it up to setting limit and charge battery.

    Others that have them installed and are using them I am sure will give pointers on functions.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • mike95490mike95490 Solar Expert Posts: 8,292 ✭✭✭✭✭
    Re: Grid Interactive question

    with the XW inverter, if the grid is fairly stable, you can use the AC1 inputs (needs 240VAC 60Hz for USA models), or if it's noisy, AC2 which has relaxed specs to allow the XW to sync to a generator. And you can use the Sys Control Panel (another small box to buy) to adjust all the settings. The Combox logger and interface, does not have access to ALL the minutia settings.
    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 ✭✭✭
    Re: Grid Interactive question
    Marty wrote: »
    I can check my smart meter for hour to hour readings the next day. Right now I'm running two cheap 500 watt grid tie inverters and I flat line my readings from 10 am to 3 in the afternoon until I plug in my chevy volt. I will talk to my local Schneiders guy and see if he knows if the XW will work.

    What kind of "cheap grid tie inverters" are you using?
    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
  • Ken MarshKen Marsh Solar Expert Posts: 114 ✭✭✭✭
    Re: Grid Interactive question
    pleppik wrote: »
    I understand that by the time you do a complete life-cycle analysis of battery storage, even the most cost-effective batteries will still cost you around $0.50/kWh.

    Just happen to have a Trojan L16H data sheet on my desk.
    It claims the C/20 capacity to be 435 AmpHr, and the battery to have 1200 50% DOD cycles.
    If this is true and using what I paid for a string of L16s 3 years ago, it works out to be 17 cents/KwHr.

    So your point is valid. This is two or three times our present incremental electric cost,
    but not as bad as 50 cents/KwHr.
  • BB.BB. Super Moderators, Administrators Posts: 29,241 admin
    Re: Grid Interactive question

    When I did the caculations a few years ago--Taking into account battery life, replacement batteries, new AC charger/inverters every 10 years, approximately 0.8 charger eff * 0.8 battery eff * 0.85 inverter eff etc... It worked out to something ~$0.45 per kWH, excluding the cost of buying the electricity itself (between $0.09 to $0.30 per kWH for off peak rates).

    I won't swear it was exactly $0.45 per kWH--but I would guess it to be in the ball park for time shifting power costs.

    In California we pay around $0.30 to $0.50+ per kHW for peak summer power costs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Ken MarshKen Marsh Solar Expert Posts: 114 ✭✭✭✭
    Re: Grid Interactive question
    BB. wrote: »
    When I did the caculations a few years ago--Taking into account battery life, replacement batteries, new AC charger/inverters every 10 years, approximately 0.8 charger eff * 0.8 battery eff * 0.85 inverter eff etc... It worked out to something ~$0.45 per kWH, excluding the cost of buying the electricity itself (between $0.09 to $0.30 per kWH for off peak rates).

    Hi Bill,
    Yes, the 17 cent figure is just wear on the battery.
    It does not include the cost of the electricity or amortization of the equipment used.
    Also, the battery cost I used is 3 1/2 years ago which was the price for the last string I bought.
    So, no doubt 17 cents/KwHr is low.

    Of interest, we have a HUP battery at an off grid cabin.
    We use as much as 80% DOD quite routinely.
    It is 6 years old and no problem yet.
    It seems to have all the capacity it ever had.
    Again using manufacture's figures, battery wear cost is about 2/3 of the L16s.
    So it looks like the more you pay up front for a battery the less costly it is in the long run.
  • BB.BB. Super Moderators, Administrators Posts: 29,241 admin
    Re: Grid Interactive question

    Yep... I try to do the back of the envelope calculations to get "close" to figure out if something is worth pursuing further.

    As always, I recommend that folks do their own paper designs too and confirm or find out something different.

    Neat to hear about how well your battery is working for you. Always nice to read about products that work better than expected.

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