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Jaco P Bloem

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    Bloemfontein
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    Electrical Engineering Powerflow

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  1. Thanks Gents, I enjoy also the information! @Leshenon a different but related topic : I know of 2 Sunsynk 8kW installations where the Earth Leakage (home DB) trips after loadshedding. They do not have an earth - neutral bond relay installed, so my quess is when the Eskom / Munic Neutral and Earth return, there is an unbalanced leakage (?). Any inputs or discussions around this that you are aware of? Kind Regards, Jaco
  2. Dankeschön @Payback2! I'm currently using the software by @Solar Assistant and is very impressed. It also utilizes Grafana. Appreciate the gesture.
  3. I'm not familiar with all the settings on this Inverter, but relating them to the 5kVa, they seem correct. I suppose setting 26 is the Charge Voltage which is fine at 2 x 14.1V. Also the float seem in order. The cable size and circuit breakers are in order as long as there is no poor connection and the cables kept short. If the installation and settings are in order, then it may be the battery quality. You should be able to cycle the 2 batteries to 50% (say 24.2V SOC) easily with a load of 175W (<6A) and this should take more than 2 hours. [In fact probably 75%, given they were sufficiently charged]. Can you ask support from the battery supplier, their opinion and perhaps they can do their own (load) test? Regards!
  4. Hi For the benefit of the Forum, could you share more on the specific batteries (make and type) with their Specs used. Secondly post the Inverter settings - so we can see the mode, Charging and Floating Voltages, etc. Keep well Jaco P
  5. Jaco P Bloem

    Paul

    This is actually great news especially for Pylontech (and I suppose similar products) owners. So the BMS will treat and charge the new pack differently than the old. I wonder if the supplier still honor the full warranty in such a case - although I understand the warranty is in any case less when used with an Axpert as the Inverter cannot communicate with the BMS (except through 3rd party software like ICC). Important : @It's On if you start too small, I.e. with one Pylontech (3.5kWh) only, there is an issue here to consider.. and this is from actual experience at a friend's installation : When the load exceeds the amp capacity of the single battery pack (70 amp in this case) the BMS will protect the battery and shut off. This in turn causes the Axpert to trip (when in SBU mode) as the DC disappears. This is with zero PV generation and you need just over 3.5 kW of load (oven + microwave) for this to happen. The battery BMS is too quick for the Axpert, we have tried different settings but before the inverter can make a decision on the Voltages, the BMS acts. We have moved this battery to a Sunsynk inverter with communication to the BMS - different story! The Inverter blends the usable battery DC with available solar and grid power without overloading the single battery. So for now with the Axpert, rather spec the battery packs large enough from the start, at least to carry your typical peak load .
  6. Jaco P Bloem

    Paul

    ..on most parts (i.e PV or even Inverter) you can expand at any time I agree. However you cannot add a new battery pack to an old unit or pairs. The cells did not age together so if you add new cells to old ones you have different charge (voltage) levels which will ultimately decrease battery life. In this case (parallel Axperts) the Battery bank is common to both the Inverters, and so you cannot expand the existing bank say after 1 year without replacing all. It is somewhat logical and is applicable to flooded / agm batteries also. I have found this post interesting : Greetings!
  7. Jaco P Bloem

    Paul

    I agree, the Pylontech batteries seem to do well, you can search for the best price. We've bought a set from Ellies, so you can ask a qoute from your local outlet, also check out Bonanza Technologies (excellent advice and support from the owner). My own set does not exist in the market so it won't help. If possible go big from the start - because the battery DC is all connected and bridged, you cannot expand easily if you wait too long. Either 3 x 3.5kWh or 4 x 2.8kWh units if possible. The single big 6 kWh @Krokkedil mentioned can also work depending on your load after sunset.. I was advised 10kWh at the time which works great in summer. For rainy days and those long winter nights it does however still switch back to Utility. Your PV will be sufficient to charge the batteries. Keep well!
  8. Jaco P Bloem

    Paul

    Hi, I have a similar setup with the 2 Axperts in parallel however I use two Lithium batteries with their own BMS. My opinion is that these Mecer inverters do not do a great job of charging, if left to it's own devices. If you are going to stick to Flooded (or agm) batteries then you will have to install a 'battery balancer' to balance the 12V units amongst themselves. The inverter do not have any intelligence to do this. I am sure I have seen units for sale in the PowerStore (?). Otherwise move to Life batteries with their own BMS, but this may be expensive.- there is great advice on this Forum for the voltage settings. PS: I presume the Inverters are in parallel with the kit, setting 28 = pal and that the battery DC (48V) is bridged to each inverter. Important also to keep the electric (wiring) distance as equal as possible between the batteries and Inverters. Let us know, good luck! Kind Regards Jaco P
  9. *or rather, the 54V sounds like settings for a 16S LiFe, we will have to find more information on your battery.
  10. Hi Do you perhaps have more information on the battery? If it is a 15 cell Life battery, the charge Voltage might be too high. I can propose the following : Bulk Charge : 52.5V Float : 51.8V Also setting 12 should be 48V then the battery will not drain completely (if this is your 'point back to Utility' setting? Setting 13 to 51 V (back to battery) If you can give this a try? It may be that the battery BMS protects itself from the high voltage (as 54V sounds more like flooded battery settings). Let us know Kind Regards Jaco P
  11. Hi Jaques A single 6mm sq cable (pair) is sufficient for the 2 strings in parallel as the source is 2 x 9.7A, so less than 20Amp. Even a 4mm is enough but yes the losses are less in the larger diameter and the given distance. In my installation I've connected the parallel strings on the roof without fuses using a connector box (self made, but I see you do get the MC4 type PV parallel connectors). It then passes through a single fuse and 30Amp Isolator switch before it goes into the Inverter. The 32amp fuse is sufficient, as stated the current will be below 20amp and less. (I do run 2 Inverters in parallel, with 2 different PV sets) I had both fuses and isolators, so I installed them but in my mind, the fuse will never blow : if you spec the fuse correctly for the load (the current draw into the inverter) in this case 20amp, then the current in the PV cable will/can not exceed that, as the source (PV) cannot give more. The 9.7A in the spec sheet is the short circuit (fault) current and the two strings in parallel gives 19.4amp. So effectively you cannot short-circuit the cable at any point before or after the fuse to blow it, as the max current is lower than the fuse rating. The only possibility for the fuse to blow is if the fuse is a poor design or rated lower than source (PV) capability and perhaps lightning - but if a lightning surge blow a fuse, chances are there is damage all over. You may consider Surge Protection on the 2 PV inputs on the Inverters - this is more sensible to me. (surge arresters of higher than 246.75V in your case) But what you have in mind will work, you have enough cable capacity for 2 PV sets already Kind Regards Jaco P
  12. Thank-you, I was wondering yes! The update to 71.82 went well - all seem normal and stable this morning.. Although now it is snowing (possibly just 'ice rain') in the Free State - go figure! But the PV is doing well, still charging (slower) and supply load through the clouds - no experience with other panels but the Canadian Solar performs well during overcast conditions. Will monitor.. I agree with the ICC issue, I monitor my batteries manually now and use WatchPower, at least to identify faults.. Kind Regards!
  13. "Wat jy meet is wat jy weet "! Thanks @pierre. I will keep an eye on your posts. Would love to get a Pi in future and learn - the complete 'plug & play' set with ICC is now above R3000 and I am not sure if that is worth it.. I am going to Flash my 2 inverters tonight or tomorrow with the 71.82 version. (I am still on the Old 71.50!) Since I took measurements it turns out I am suffering from the premature float issue. I am using 52.5V Charge and 51.5V Float values (15s LiFeP) - thanks @plonkster I have learned a great deal from your posts and the 'correct but low as possible' settings that I have seen @Coulomb propose, works well for me. The Axpert Inverters gets the estimated SOC totally wrong - During the day with PV available and there is a low load while the batteries show 100%, the Inverter display battery Voltage (and WatchPower) will jump to over 60V!? I have seen a few ' battery Voltage high' faults recorded and that explains my infrequent early afternoon trips + resets. I am confident this is a measuring issue and not the battery BMS. My supplier agrees and Voltronic send a link with the exact same file as posted by Pierre. PS: I have an 'old faithful' i7 laptop with a serial port, so will use the Serial to RS232 inverter cable - hope it will run smoothly.. Keep well! Jaco P
  14. Hi @Pierre and all After measurements using WatchPower ("no cloud, poor sample rate - put laptop in 'no sleep mode' and export to Excel" method).. the output Voltages on my 2 parallel Axperts inverters do seem to be stable at around a 1% fluctuation, for this day at least. The batteries were below 47V (setting 12, to give app. 20% left on the LiFe's) just after 6am so the inverter switched to line (grid) mode. The rest of the day consisted out of battery charging (20Amps x 2), app 1kW from each array.. back to battery mode just before 9am..and normal home loads (washing day).. (sorry about the picture quality! Output Voltage 1 and 2 is the same as they are bridged on the Inverters.) If zoomed into the Voltages during high and low loads: The fluctuation is exaggerated i.t.o the scale on the right, but the actual (orange and green) outputs are stable in both Line and Battery mode. One should expect greater stability in line mode as the fault level (firmness) of the Utility is much greater than the installation (you cannot beat the massive rotating machines of Eskom ) but to be fair the variance in both cases seem similar around 1%. The home loads are quite 'rouge' especially fridge compressors! The power spikes (related to voltage dips) are noticeable during the night (and day) - also they are more noticeable to the naked eye in battery mode - lights dim/dip. In line mode you will seldom 'see' a fridge compressor switch on - again due to the fault level, or the firmness of the network. This is also the reason why more battery packs are more stable - they add more firmness. If you run the Inverter without a battery (as these models can), you run in all sorts of Voltage issues and fluctuations especially when the grid falls away (i.e load shedding) as the fault level from only the panels is very low (poor), so low firmness. 9amp from a serie PV string vs. +100amp from a single battery (example). (I've witnessed this at an installation close by). Similar to you, I have 2 x 100a/h Lithium Iron batteries - wish they were 4 but it is expensive as you know. Trust your installation is running smooth and stable after the firmware upgrade! Kind Regards Jaco P
  15. ..one thing I do not have is good monitoring software! Are you using ICC on the Raspberry Pi? My first installation (2019) is 12 x 330W Canadian Solars, the array is two parallel strings of 6 in serie each. I have now added the second inverter with 8 x 360W Panel array all in serie to the second inverter - running in parallel with the first Axpert. Hats of to the mppt chargers referencing different input voltages (223V DC on the one and 317V on the other), and still maintaining equal power drawn. When the load exceeds the capability of one of the PV arrays, then only will the first array ( my old set) supply more than the other - to a point where both give max for the time of day.. Just by watching the Displays and WatchPower I do not see major fluctuations (227 to 233 Vac which is 1.3%) but I will have to record the Voltages to see if I have a similar drop - that you and others have noticed. It's difficult to comment on your graphs as one must compare them with the Voltages and also I am sure you have Battery usage and charging as well (?). Thanks for sharing! ((PS: I see a 10% PV power increase in my old array each time I wash the panels - it's dusty in Bloem! )) Jaco P
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