Semi Isolared solar sysem

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EdwinJacob
EdwinJacob Registered Users Posts: 10 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
Hi friends, I have a question to ask. I want to install a semi isolated system in my house. Here in Mexico, in the region where I live, there are no interconnection permits to the electrical network by the energy company. however I have read about a solar system that works only through self-consumption without injecting into the grid, someone knows what the installation consists of. What equipment do I need to install so that only the energy generated by my system stays inside the circuits of my house without the need for it to go out to the grid.

Greetings and a strong hug.

EJL
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    I think what you are describing is Zero Export.    So that is a keyword to look for in an inverter.   Will this be a simple grid-intertie, or are you using a battery system ?  Many Hybrid Battery system inverters have zero export settings. ( also called load shave)
    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

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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    edited November 2021 #3
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    When a hybrid inverter is locked onto grid freq and voltage it runs in parallel with grid and load connections.  It has current sensors to determine where the current is flowing.  Inverter pushed power can go to output loads or grid backfeed.

    For a hybrid inverter, if it raises its inverter output voltage slightly it pushes current into the common connected grid-AC output node.  If it lowers its voltage slightly it charges the batteries from grid (or generator). 

    For zero export to grid it is a feedback control sensing to adjust inverter pushed power to supply AC out loads but tries to keep backflowing current to grid to zero.  It does allow power to be pulled from grid to charge battery or supply AC output loads.  If you have PV charging battery it will adjust inverter output to supply AC output loads but will back down charging if battery is fully charged and incoming charging power exceeds what can be consumed by AC output loads to prevent power being pushed to grid.

    This is a cousin to, but different than load shaving which adjusts inverter output level to keep incoming grid current below a set desired maximum level.  This uses battery power, including PV charge current, to suppliment grid power, lowering power consumed from grid.  When battery gets too low in state of charge it gives up on load shaving.

    For a battery-less grid tie inverter there are kits that put current and voltage sensors on the main incoming grid connect wires to the main breaker to sense the power flow from grid.  This allows GT inverter output to be modulated in much the same way as hybrid inverter described above does to prevent any power push into the grid.
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