Can the PLUG AND PLAY inverters be used safely in conjunction with a TRACE 4024 off grid system?

mrleemus1mrleemus1 Registered Users Posts: 28 ✭✭
i have 6 solar panels BP 175 that are just lying around here. What i thought i would do;  would be to mount them on a rack  and orient them toward the souheast  to capture the early morning sun specifically and plug it in to a wall socket. - That way i would have power to run household appliances in the early morning like from about 8:00 till 10:00 without causing a battery drain. Can this type of inverter be used with a Trace 4024 off grid system?

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,999 admin
    In theory, yes... The Trace seems to be a TSW/PSW (true sine wave) inverter--As long as its frequency and voltage regulation is stable enough (not all inverters are)--And the plug and play GT inverters are 120 VAC to match the Trace output... I guess try it.

    However, there are warnings. First many of the plug and play GT inverters (at least in the US) are not UL/NRTL approved, and have a poor record of reliability (and possible overheating/fire).

    Second, if you have a GT inverter "back feeding" an Off Grid inverter, you run the risk of over charging your battery bank--The Off Grid inverter will recharge the batteries until something fails. You need a secondary charge controller (dump controller on battery bank, a controller that turns off the GT inverter output, or even a pair for redundancy) to ensure your system is safe.

    There are a few new Off Grid/Hybrid inverters that do have the ability to take GT inverter power and regulate battery charging--But the older inverters were never designed for it.

    Presumably, short term testing to see if it works won't damage anything... But if you leave permanently connected, some way to control GT battery charging is imperative--It is too easy to cause a fire if you do not.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mrleemus1mrleemus1 Registered Users Posts: 28 ✭✭
    Bill--- thanks for your prompt response..
    Do I understand correctly that some how the "back fed" 1000 watts of 120V AC - that is plugged into the wall socket gets " inverted or changed" back  to DC current and flows back into the battery bank?? It is difficult for me to understand how that happens. Does the Trace 4024 system see that "back fed" Ac as the output from a backup generator and lock on to it and then goes into a battery charging mode?
    Lee
  • BB.BB. Super Moderators, Administrators Posts: 32,999 admin
    Lee,

    Yes... It turns out that many AC inverters will actually support "bi-directional" power flow... It is hard to believe, but when the AC line voltage is "higher" than the Off Grid AC inverter's output voltage, you get reverse current flow (and reverse energy flow) and the OG Inverter behaves like a "synchronous rectifier" (a S.R. is a term where instead of using diodes to turn AC into DC power, the hardware uses transistors and electronic circuitry to turn on/off the transistors at the right time--In electronics, this can save energy as diodes lose more power than switching transistors).

    This works because the GT Inverter is (typically) a "current source".

    If you connected a "voltage source" (generator, utility power,  etc.) to the ac output of an OG inverter, you will have smoke, fire, and/or a dead OG inverter.

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