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Coulomb

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Coulomb last won the day on July 27

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About Coulomb

  • Birthday 05/11/1958

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    Male
  • Location
    Brisbane, Australia
  • Interests
    Solar energy systems with storage; firmware for inverters and chargers

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  1. Through the shared battery. Each inverter uses whatever battery power it needs, and each inverter provides as much power as it can to the battery, if it can accept the power. So the inverter with most of the loads might be a different one to the one that has most of the available PV power, but the power flows from whichever PV to whichever load.
  2. Is this because of the premature float bug? They copied that too? Is there no setting 32, or 33-39? That's really low. For battery life, I'd bump that up a fair bit. At least 46 V. Since you're using this as a UPS, and load shedding seems to be more or less regular, this changes from a once or twice in the life of the battery emergency event to a routine shutoff point.
  3. You mean the RS-232 port? It's possible to update main (DSP, U1) firmware through the USB port via an on-the-go cable, and I'm trying to figure out whether it's possible to update the removable display firmware that way as well (some have reported problems). Have you attempted to obtain a replacement removable display? That would seem easier than replacing the whole inverter.
  4. Do they both have setting 28 set to PAL? Don't forget to have the inverter switch off when changing this setting. If not, it has 230 V applied to its output when it tries to generate power, so it sees this as a short circuit (which it is in a way, just short circuit to another voltage source, rather than short between its own outputs. That's pretty weird. I have no good ideas. Perhaps leakage between AC-in and AC-out? It's hard to imagine you'd read the exact same voltage, though.
  5. Well, most other inverters with hazardous PV voltages have insulation monitoring (testing, and alarm if there is a failure). It doesn't overcome panel leaks, but it might have prompted installers to know to use different brands of panels long before yours got installed. Edit: most modern inverters are "transformerless" grid tie types, which would have the same sort of voltages at the PV terminals. Of course, other than the safety hazard and alarm, they might cope with the leakage just fine (i.e. continue operating).
  6. The manual quotes "98% max". At these relatively low power levels, I'd expect at least 95%. Axperts do have a fairly high self-consumption, of the order of 50 W for a 5 kVA model; Kings might be slightly higher with the extra AC-DC converter. So about 5% efficiency and some 10% from self consumption brings it to roughly 85% at that power level. But it's not clear to be whether self consumption would be counted against the PV production; it seems more likely that it would not.
  7. I don't have time to investigate at present. It's possible that this is by design; after all, SBU means that U (Utility) has the lowest priority. The VM III firmware that I have (now quite old) has the most complex mode switch behaviour of all the firmwares I've looked at.
  8. Certainly fault code 80 (CAN data loss) can cause a shutdown; any fault puts the inverter into fault mode, which doesn't do much. It might charge the battery (possibly only from solar, and possibly only on 145 V SCC models), and it might power the loads from utility. Not much else. I'm surprised you see the fault after a shutdown. Faults aren't stored like trouble codes in your car; they are the result of things happening while operating. In the case of fault code 80, the slave has to not see CAN comms for a certain amount of time. So I don't see how it would happen immediately after a shutdown. My guess is that you have some problem with either a paralleling cable (probably the VGA-like grey cables rather than the red-black twisted current share cables), or the parallel cards that these plug into. There is a small chance it could be some other electronics (buffer chips, for example) between the paralleling boards and the DSP. I assume you've checked the cables for tightness. I'd consider purchasing a paralleling kit; that would give you a new board and cable set; start swapping them about to see what makes a difference. If you find it's hardware, you may be able to get your supplier to refund the kit.
  9. Actually, it's 2 minutes, but that's (so far) only in the fully patched firmwares. From memory, it's a one word patch, so I guess it could be done in a minimal patch. But see below. Kings have very different firmware to the Axpert MKS models, which so far are the only ones that have fully patched firmware. None at present. Only an old, very lightly patched firmware is even available for Kings, and it doesn't reduce that delay. Weber and I would like to do a fully patched King firmware one day; I'll post about that on the King firmware topic.
  10. ? You certainly can't parallel an Axpert MKS with an Axpert King, if that's what you are suggesting. I can't think of an easy way.
  11. The relays are rated at 40 A, and there is a 40 A breaker at the AC-in connection. So roughly 40 A x 230 V = 9.2 kVA (depending on the Eskom voltage). Depending on your load power factor, that might be around 7.5 kW. Edit: that assumes that your cables are rated for 40 A, of course (6 mm²), if you want to pass that power continuously. With 4 mm² cable, you should limit to 30 A continuously for safety. Yes.
  12. Remember that the PV current is always battery-side current, not panel current. In some models, it's net current into the battery; for others, it is total charge current (sometimes there is a screen for both). I'd say you are seeing net charge current (factory firmware treats discharge as a separate current, so this never goes negative). So it is probably just that at times you have ~ 6 A x 50 V = 300 W more PV power than load power (ignoring losses). To figure out what the panels are doing (from the inverter), use the PV power screen. It's always total PV power (never net). It should be around 107 V x 7-8 A x 3 ≅ 2250 - 2500 W.
  13. You really need to do your own research. If they look like the modules in the photo on this page: https://www.slideshare.net/NaveedAhmed232/narada-200-ah-data-sheet it states that the maximum charging current is 50 A per module. Note: Narada make a lot of different types of batteries; check that this matches your modules, and if not, find the right specifications. With two strings, that makes 100 A max. The 15% of capacity rule of thumb is meant to be safe for all lead acid batteries; some are made different to others, and can take the extra current due to their design. So I suggest that you use 80 or 100 A. Hopefully, Growatt have fixed the premature float bugs; if not, it may be better to set the current limit lower, about what you might expect from your solar on a good day.
  14. The fuse is to protect panels from fire if there is a short in a panel, not protect the inverter's charge controller.
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