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Calvin

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Everything posted by Calvin

  1. The 80A is essentially the maximum recommended value. If your batteries will charge fully at a lower setting, by all means use it. Generally, lower current is better as the power wasted (because of the internal resistance of the battery) goes up with the square of the current. This wasted power also heats the batteries, which is not a good thing.
  2. I have done this, and it is indeed not trivial if you want to do it well. The biggest challenge turned out to be finding how much excess PV is in fact available. When the battery is charging at the maximum allowed current (or is full) the SCC will clip it's output to what the system can use. First I tried looking at the MPPT voltages - the logic being that if they are higher than the maximum power point, the SCC has pushed them up to reduce power, so there must be spare PV out there. This worked OK but not fantastically - perhaps complicated by the fact that I have 3 inverters in parallel but with each SCC doing it's own thing. Next I tried the approach of slowly increasing power to the geysers until the batteries started discharging. This worked well when loads and sunshine were consistent, but otherwise badly. Finally I started measuring the solar irradiance directly (using a separate small panel). Even this is no exact answer, as my Axpert's SCC reacts much more slowly than my home-made pyranometer to intermittent sun. Perhaps other manufacturers' SCCs are better. My eventual solution uses a combination of all 3 methods. It works fine, but it is not simple. In my case I can control the power to the geysers exactly. If you have simple on/off control you face the additional decision: Do you run the geyser when there is say 1kW of extra PV available, taking the rest from battery / grid? Given that neither is a cost-free option, not a trivial decision.
  3. The inverter setting is total charging current, not per battery. So, you should set 80A - it will be divided by the BMS between the batteries.
  4. I am also a farmer with similar usage as you. I have gone off-grid for the sort of cost you are talking about (R350k because it was DIY), but be aware that you may need to buy at the lower end (Axpert) rather than the Victron at your budget. Real key is whether you intend keeping the ESKOM connection (with it's massive fixed connection charge), switch to a Land Light 60A single phase (no connection charge but over R5/kWh) or drop ESKOM entirely. For me the sensible option ended up the 60A single phase - it is essentially a hassle free generator at lower costs than running a generator. That way you can size your batteries to keep you going overnight and run on ESKOM only during extended bad weather (I have just run through the Cape winter without using any ESKOM power at all). The batteries are the single biggest expense. Be very careful with VAWTs. See this blog https://scoraigwind.co.uk/2016/12/what-is-it-about-vertical-axis/
  5. It is quite simple in principle, but as is often said the devil is in the detail. Essentially the microcontroller measures the available incoming PV, the outgoing AC (to loads) and DC (to the battery) and estimates the system losses in order to calculate what spare power is available. It then adjusts the power to the geysers every second to use exactly this excess power. The only problem with it is that it is complicated (it does many other things) and home-grown - I used to do this sort of thing professionally and now that I am retired it is my hobby. Unless you are a competent programmer (in C/C++) and handy with electronics you would probably need to wait until somebody commercialises something like this. Below is the diagram of the entire system. The microcontroller is the blue box labelled "Arduino Due". The DS18B20s are temperature sensors. The triacs (and supporting circuits, not shown) could be replaced by suitable solid state relays.
  6. Quite right. I have a microprocessor that controls my energy system and it also controls both my 3kW geysers with triacs, meaning that I can send any excess energy to the geysers. The beauty of using analogue control is that you don't have to wait for 3kW to be available - you can balance the system perfectly. A further advantage is that you now really don't need extra inverter capacity for your geysers - the system monitors for overload conditions and switches off/reduces the geyser power instantly if too much other loads come on line.
  7. Axpert, Mecer, Kodak RCT and many more are brand names. All these inverters are in fact simply re-branded Volronics inverters. VMIII, Kings MKS are models, sold under all the different labels. So, a Kodak King is the same as a Mecer King, but a Mecer VMIII is very different from both. So, the key is the King or VMII part, not the Kodak or Mecer or whatever. Hope this clarifies it. Ignore everything I said earlier - my knowledge / advice is limited to the Kings.
  8. NOOOOOO! It REALLY can only be one or the other.
  9. Does the display show battery charging happening? (Use Watchpower if you do not know where to find it) What is the battery voltage? Is it in PYL mode (setting 5)? If yes, try setting 5 USE setting 12 47V setting 13 51V setting 26 52.5V setting 27 50.5V setting 29 45V
  10. This makes no sense. The utility supply is disconnected, and yet the inverter is drawing 480W from it? There are several people here with the knowledge and inclination to help, but we are flying blind. May I suggest that, in order to get assistance, you provide the following information: Inverter model Firmware versions Settings actual values of power from the LCD Of course the inverter could be faulty, but the chances are far greater that there is a problem with the settings or setup. For reference, the King uses about 80W when fully powered up with no loads.
  11. Calvin

    Optimizers

    Something I wrote when planning my own installation. I will upload it as soon as I have had a chance to polish it a bit...
  12. This should work: 1. Charge each battery individually to 100%. You will probably need to disconnect the others. 2. Reconnect, making sure that the 3.5 is master (Link port 0 unused)
  13. Calvin

    Optimizers

    12/4/4 below Just to put it clearly: below is the numbers for North vs West vs East on 1 July in Pretoria (26 degrees panel angle) As you can see the West and East facing panels are not bringing much to the party. Slight gains early / late, huge losses rest of the time.
  14. Calvin

    Optimizers

    No problem - adjusted to 26S 28E All 16 North 4 West, 12 to North 4 to West, 4 to East, 8 to North You need to be careful here: moving panels like this gives you more early and late, but in July total daily production decreases from 5.4kWh to 4.4kWh (per kW installed). Given that most of us size our systems for winter, losing 20% in winter is not ideal... Also note that these figures are for the case where each bank has it's own MPPT to optimise it's production. If you combine different orientations on the same MPPT you will lose a lot more. Summary: at our latitudes, having East/West panels gives you more power early and late in summer, at the expense of some midday power. In mid-winter it gives you no extra power ever, and costs you 20% on average (with your 8/4/4). To see how bad the East-West is in winter, here is a graph with all 8 East and 8 West. You can see that July is now down to 3.4kWh/kW.
  15. Looking at your graphs it appears that you are already wired 2S. Given that a hardware issue is unlikely (2 different inverters), the strongest remaining possibility is in your settings. (I have had similar behaviour on my King when I had screwed up a setting) Please list all your settings, and the inverter firmware version.
  16. Calvin

    Optimizers

    No problem, see below (all assuming Cape Town - let me know if you are somewhere else) I saw you were considering moving 4 to the West: This is how it would look And finally, 8 North, 4 West, 4 East This last one is wrong, but the forum software does not allow me to delete it....
  17. The cable that works for me: Axpert King <--> Pylontech Pin 3 <--> Pin 8 Pin 5 <--> Pin 7 no other pins connected The first cable in your list looks like a reversible version of this.... No patched version for the King yet - @Coulomb somewhere said hopefully by year end.
  18. When you use the King in PYL mode the flashing battery icon indicates that the comms with the Pylontech BMS is working When adding panels, take care to add them 2-in-series (2S) rather than 3. The specs just about indicate that 3 should be OK (145V max) but it can lead to all sorts of problems.
  19. It could also be because of overheating of the SCC PWM. On my inverters (Kings) there is a control that reduces PV power when the SCC PWM temperature (as reported by the Q1 command) reaches 87C. Interestingly this only happened when I ran my panels in 3S - since I changes to 2S the SCC PWM temperature never gets near 87C. Not sure if the high voltage models would muse the same logic, but it might be worth checking (if you have the ability to run terminal commands)
  20. Can think of only 2 reasons: No mains - (circuit breaker tripped, power failure). Can you check with a multi-meter that there is 230V on the input to the inverter? Inverter faulty.
  21. @David27 lots of confusion here, as you never said which model you have. Kodak sells many Voltronics- the King, MKS, etc. From the manual you linked to I think that yours is the MKS II (high voltage MPPT) The settings that @Coulomb referred to are for the King, where Bypass/ECO is an operational mode that bypasses double conversion "line" mode. The MKS II does not have this mode.
  22. On my setup (3 Kings on 71.93 / 2.49) menu options 10 and 23 are there, but have no effect whatsoever. I cannot get it into bypass/ECO mode under any circumstances. This seems consistent with the manual. Reading it literally, the only way you can see the "Bypass" on paralleled Kings is when it is in Fault Mode (page 29). All the operational bypass modes have the "disabled in parallel mode" note next to it.
  23. I don't think that Kodak has anything to do with these. Somebody (presumably) got permission to use the Kodak name on this inverter in SA only. It is simply another re-brand of the standard Voltronics product.
  24. This is an issue with the inverter when it is set to PYL mode. The inverter asks the Pylon's BMS for the target voltage, and it replies with 53.2V (53.25V to be exact). This is on the high side, but would be OK with an inverter that does not overshoot. Unfortunately the Axperts do overshoot the target, causing the BMS to send a message to stop charging. This is displayed on the inverter as the famous message 69. In earlier versions of the firmware this caused an error that shut the entire system down. Now it is only a warning. Most people run the inverter in USE mode with a absorb/bulk setting of about 52.5V and float at about 50.5V. The 53.2V is far too high - apart from the 69 warning it is bad for the life of the battery to be kept at such a high voltage.
  25. I think you may be confusion "line" mode with "Bypass/ECO" mode. In the King, line mode is double conversion, whilst ECO/Bypass mode connects AC in directly to AC out. From the manual (for the "PYL" setting): "If selected, programs of 02, 26, 27 and 29 will be automatically set up. No need for further setting." Essentially the firmware controls these settings when in PYL mode. Bypass/ECO mode is controlled by settings 10 and 23, but is disabled when running in parallel mode. The firmware for the King is at best a "work in progress", and the combination of parallel and Pylon is something that they clearly have not yet spent much time on. Other than @Plaashaas I know of nobody who has got Kings in parallel to work on PYL setting. My standard advice is to use the USE setting and use something like ICC or solpiplog or from the thread below.
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