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Looking for ideas on how to incorporate a generator in a large solar system.

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  • Farvaszx6r
    replied
    Originally posted by ButchDeal View Post

    You seem to be mixing dump loads like a water heater and battery management.
    there is no need for a dump load with a well configured AC coupled system as the bimodal inverter can regulate fully the grid tie inverter.

    as for battery management, well that is on you 100% if you are building a custom battery bank.
    Charge controllers do not balance you battery bank, the charge only.
    also in an AC coupled system there are no charge controllers, they are only used in DC coupled systems.
    Thanks.

    Leave a comment:


  • ButchDeal
    replied
    Originally posted by Farvaszx6r View Post

    From what I read online in ac coupling there is no way for the inverter to balance the battery packs and there was a need to have a dc consumer like a water heater to balance. I was going to use bmc to balance individual modules and use charge controllers to balance pack voltage. But I suppose that the bmc's would regulate the pack voltage by regulating modules.
    You seem to be mixing dump loads like a water heater and battery management.
    there is no need for a dump load with a well configured AC coupled system as the bimodal inverter can regulate fully the grid tie inverter.

    as for battery management, well that is on you 100% if you are building a custom battery bank.
    Charge controllers do not balance you battery bank, the charge only.
    also in an AC coupled system there are no charge controllers, they are only used in DC coupled systems.
    Last edited by ButchDeal; 10-25-2019, 11:54 PM.

    Leave a comment:


  • bcroe
    replied
    You are getting good advice here, stuff on this scale is not plug and play. The Wright
    brothers became good engineers, developing their own launch system, gas engine,
    and a high efficiency propellor.

    The usual start point on these projects is compile just exactly how/where your energy
    is being consumed. Getting rid of the obvious waste would be next. I am wondering
    if air conditioning is much of it? The newest AC units can cut energy use to less than
    half (as is happening here), and there are some units designed to operate DIRECTLY
    from solar panels (grid backup). They will not do much under clouds, but that is not
    when they are needed.

    If the housekeeping stuff is under control, run the generator for welding or the well,
    avoid all the issues of batteries. good luck, Bruce Roe

    Leave a comment:


  • Farvaszx6r
    replied
    Originally posted by ButchDeal View Post


    i am not sure what you mean by a DC load to maintain the battery.
    There is generally no ned for any load on many backup systems. They sit waiting for an outage.
    From what I read online in ac coupling there is no way for the inverter to balance the battery packs and there was a need to have a dc consumer like a water heater to balance. I was going to use bmc to balance individual modules and use charge controllers to balance pack voltage. But I suppose that the bmc's would regulate the pack voltage by regulating modules.

    Leave a comment:


  • ButchDeal
    replied
    Originally posted by Farvaszx6r View Post

    Fair enough.

    It looks like a grid tie system ac coupled battery backup is the best option.

    Why is it not feasible to run the whole house off of an ac coupled battery backup? Not the whole property just the house.

    If I use an ATS to power the main panel with battery backup would I be able to use an ATS between the solar edge inverter and generator to charge the batteries and run the house if there isn't enough solar production? There are times when the grid is off for several days due to poor weather conditions.

    How much of a dc load is required to maintain the battery bank.
    Sure you could run just the house and would need atleast one bimodal inverter that is larger than one of your grid tie inverters.
    most bimodal inverters have multiple AC connections so that one is dedicated to the inverter

    i am not sure what you mean by a DC load to maintain the battery.
    There is generally no ned for any load on many backup systems. They sit waiting for an outage.

    Leave a comment:


  • Farvaszx6r
    replied
    Originally posted by ButchDeal View Post


    Lots of people live in rural areas and have grid tie systems. It makes far more since for you to backup with a generator with your LARGE backup loads.
    But more so the entire plan will not work.
    Fair enough.

    It looks like a grid tie system ac coupled battery backup is the best option.

    Why is it not feasible to run the whole house off of an ac coupled battery backup? Not the whole property just the house.

    If I use an ATS to power the main panel with battery backup would I be able to use an ATS between the solar edge inverter and generator to charge the batteries and run the house if there isn't enough solar production? There are times when the grid is off for several days due to poor weather conditions.

    How much of a dc load is required to maintain the battery bank.

    Leave a comment:


  • ButchDeal
    replied
    Originally posted by Farvaszx6r View Post

    I want to spend less then $500 to $600 a month on energy and I want reliable power.
    These are two different goals.
    The cheapest and most reliable way to get the lower cost energy is with a grid tie system.
    The reliable power for your huge loads is best done with a generator.

    Leave a comment:


  • ButchDeal
    replied
    Originally posted by Farvaszx6r View Post
    Yes it is not a bimodal inverter but it has been used in ac coupled hybrid systems with out lg batteries.
    You are not doing an AC coupled system. In an AC coupled system the bimodal inverter is the one that does all the real work for backup.
    Now if you want to couple your system with a bimodal inverter like those from Outback and a 48V battery bank it will work fine. Though I think you need to consider a SMALLER backup system of just critical loads. If you want to run your welder off grid then start up the generator.

    Originally posted by Farvaszx6r View Post
    I also want to do an off grid 3 phase system for my shop because 3 phase equipment is substantially cheaper then single phase.
    3 phase off grid equipment is substantially more expensive though. Your best bet there would be outback systems which can be stacked in 3 phase configurations. 3 Inverters, one per phase. or 6 ( two per phase) if you need more power.

    Originally posted by Farvaszx6r View Post
    perhaps it is a day dream but that's what people thought about the Wright brothers.
    ​​​​​​​
    The wright brothers invented not only a plane but the equipment needed to design a plane like a wind tunnel. You are trying to assemble something, not invent something. but are trying to use the off the shelf parts in ways that they are not only not intended but are not going to work.

    Originally posted by Farvaszx6r View Post
    I thank you missed the part about using a rectifier bridge. I use high voltage rec bridges at work that are rated at 1000v and 400amp and the parts to make one are relatively inexpensive and easily accessible.
    ​​​​​​​
    I think you missed the part of the SE7600H not having a DC input for a battery. You can convert your generator output to 400V DC but the inverter is not going to like it and not going to communicate with it. The voltage is NOT a constant 400V, it fluctuates based on grid voltage as well as inverter capacity.

    Originally posted by Farvaszx6r View Post
    This is true but now we are substantially increasing amperage loads and wire size both are costly in large solar systems. Also I want something that is easily reversed and can be reconnected to the grid because not many people will want to deal with a complex system.
    ​​​​​​​
    well off the shelf 48V systems are pretty common. what you are talking about is not only not common but will require a special permit for any battery over 48V ...

    Originally posted by Farvaszx6r View Post
    Then would it make more sense to break up the array into multiple arrays with their own charge controller?
    ​​​​​​​
    I fail to see how that will help.
    There is NO charge controller with a solarEdge system. The optimizers are directly attached to the PV modules and connected in series to the inverter. The inverter will not work without the optimizers.
    It seems like you are trying to remove the optimizers,
    and connected the PV modules in series to charge controllers (rapid shutdown code violation ),
    the charge controllers to a bank of 400V batteries,
    and the batteries to the PV input on the inverter.

    ​​​​​​​None of this will work.
    Do you even have a charge controller that can charge a 400V battery?

    Originally posted by Farvaszx6r View Post
    What I meant was using a small inverter that pulls power from the battery bank to keep the solaredge on and to activate rapid shut down should something catastrophic happen. Something similar to how they are used in hybrid ac coupling battery backup systems.
    ​​​​​​​
    That is not how a bimodal (hybrid) AC coupled system works. You have to have a bimodal inverter that is LARGER than the grid tie inverter. So in your case you would need two 8kW bimodal inverters and large battery banks at 48V (that the bimodal inverters can use.)


    Originally posted by Farvaszx6r View Post

    That would be nice if the grid was reliable. I live in a rural area not in the city. If power outages were a once and a while thing I would do like the rest of the mainstream solar systems.

    In your opinion what would be a more plausible off grid solution given the energy requirements I listed in the original post?
    Lots of people live in rural areas and have grid tie systems. It makes far more since for you to backup with a generator with your LARGE backup loads.
    But more so the entire plan will not work.

    Leave a comment:


  • Farvaszx6r
    replied
    Im not really concerned about roi. I have budgeted 50k for this project and 30k of that went to the grid tie system.

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by Farvaszx6r View Post

    I want to spend less then $500 to $600 a month on energy and I want reliable power.
    Perhaps a better way to phrase my question: Does ROI or time to payback have any consideration in the decision making process ?

    Leave a comment:


  • Mike90250
    replied
    Originally posted by Farvaszx6r View Post
    ...

    The inverters Im going to use are solar edge se7600a-us they are a grid tie inverter with a max input dc voltage of 500vdc and a nom of 240vdc to 350vdc. Each one has a 240vac output @32amp and can be phase synced.
    You will have to use a UPS battery based inverter, or find a way to disable the MPPT controller of a solar inverter. The MPPT input is expecting a CURRENT SOURCE, batteries are a Voltage Source and will not work well with a MPPT controller. Most likely, the battery will win and fry the MPPT controller in a couple minutes. MPPT controllers operate by adjusting the PV array voltage till they get the best current. That can't be done with a battery, the controller will start the voltage sweep and something is going to fail.

    Leave a comment:


  • Farvaszx6r
    replied
    Butchdeal some how my replies got mixed in with your quotes.

    Leave a comment:


  • Farvaszx6r
    replied
    Originally posted by J.P.M. View Post

    Thank you. Understood. What role does overall cost effectiveness play in the plans ?
    I want to spend less then $500 to $600 a month on energy and I want reliable power.

    Leave a comment:


  • Farvaszx6r
    replied
    Originally posted by ButchDeal View Post

    That is NOT a bimodal inverter and will not work with a battery unless you get the as yet not released StorEdge interface to add to it, as well as auto transformer and approved battery with digital connection (I.E LG Resu10H or future SolarEdge battery).

    Yes it is not a bimodal inverter but it has been used in ac coupled hybrid systems with out lg batteries.


    I would suggest that you stick with grid tie. off grid is never going to pay for itself.
    Backup for some loads is different though still not likely to pay for itself is much less of an expense.

    That is the plan at this point. I am fully aware that going off grid is not a financial decisions for me it is both curiosity to see if it can be done and a deep despise for pg&e. I also want to do an off grid 3 phase system for my shop because 3 phase equipment is substantially cheaper then single phase.


    Well what you have been talking about is not going to work and is not designing but day dreaming...

    That is why I'm asking questions before I go spend money and perhaps it is a day dream but that's what people thought about the Wright brothers.

    The SE7600H requies 400V DC input. Most 408V generators are three phase AC.
    More so though the SE7600H does not have a battery interace, it will eventually connect to the StorEdge interface which will also need a 400V battery and it will have to be a smart battery that communicates to the StorEdge interface ditigally.

    I thank you missed the part about using a rectifier bridge. I use high voltage rec bridges at work that are rated at 1000v and 400amp and the parts to make one are relatively inexpensive and easily accessible.

    There are MANY 48V inverters that can work with that battery like from OutBack, Schneider, etc etc.

    This is true but now we are substantially increasing amperage loads and wire size both are costly in large solar systems. Also I want something that is easily reversed and can be reconnected to the grid because not many people will want to deal with a complex system.


    No, the optimizers do the voltage regulation and the communicate on the DC lines. The battery has a separate communication on the modbus, and does not communicate like the optimizers.

    Then would it make more sense to break up the array into multiple arrays with their own charge controller?

    WHERE are you getting this understanding? it is far from accurate and will not work.

    My apologies that doesn't make much sense the way I wrote it. What I meant was using a small inverter that pulls power from the battery bank to keep the solaredge on and to activate rapid shut down should something catastrophic happen. Something similar to how they are used in hybrid ac coupling battery backup systems.


    Then stay ON GRID.
    That would be nice if the grid was reliable. I live in a rural area not in the city. If power outages were a once and a while thing I would do like the rest of the mainstream solar systems.

    In your opinion what would be a more plausible off grid solution given the energy requirements I listed in the original post?
    Last edited by Farvaszx6r; 10-25-2019, 03:51 PM.

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by Farvaszx6r View Post

    I have already started changing out major appliances for more efficient ones and I'm in the process of making the house more energy efficient. I run a side business from my home that requires me to use tools like a welder, air compressor and other power tools.

    If need be I can cut my energy consumption in half and run my shop off of generator power only. I'm just planning for the worst case.
    Thank you. Understood. What role does overall cost effectiveness play in the plans ?

    Leave a comment:

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