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Trober

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    Pretoria
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    Electronics, Music, Aviation

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  1. Hi GerhardK83, a) I bought the batteries privately from a friend, Inverters from The Sun Pays, Panels from ANH Technologies. (JAR 375W 72 cell) b) 2 houses and 2 workshops totals around 32 kwh daily - max load I've seen around 9kw. c) no comms between inverters and batteries - I monitor inverters with WatchPower and batteries with my own interface and SW via the RS485 port.
  2. Very well explained, thanks Plonkster. The likelihood of the double earth fault scenario here is very low, so for now, only one fuse.
  3. So it has been a full week now and even with mostly cloudy days, I've not needed Eskom or Generator at all. Truly Off-Grid! I'm thoroughly impressed with the JAR PV's power delivery under cloud, the inverter power management and the battery performance. The highest loads I've had was 60% of the 12kW max, lowest SoC was 75% of the 33.2kWh pack and PVpeak was 8.2k W (of 8.8kWp) I've kept a close eye on everything and did a lot of "energy management" manually. Mostly switching on loads when there was excess energy available after the battery was fully charged. These loads included filling water tanks, topping up geyser temps, running aircons and, pumping up air compressors. This will be way too time consuming to sustain indefinitely. Since I do embedded uP hard and software for a living, I'm thinking to design a controller to automate these functions. I've identified the following requirements/wish-list so far: 1) Monitor & Configure up to 4 inverters via RS232 (inverters need the latest version firmware for ON/Off control) 2) Monitor BMS via RS485 3) On a small GLCD, display the following: Batt SoC, percentage outgoing inverter load, percentage incoming PV power (all averaged from inverters data streams) 4) Allow user options/changes/configurations/setups with a rotary knob and the GLCD 5) Switch on/off specific prioritized loads (geysers, aircons, compressors, water pumps etc) via Power Line Communications(PLC) modules. 6) Monitor possible lightning approaching (AS3935 lightning sensor module I2C) and also PV Tamper wire sense loop. 7) Control a motorized PV DC multi pole switch (with large Off-state switch gap) via RS232TTL Communicate with a Generator Controller for start/stop/switch-over etc functions via RS232TTL 9) Add a BTLE module (RS232TTL) for comms to a PC on a network with Internet (perhaps a WiFi Module?) 10) Add a 433Mhz Transmitter for messaging my alarm system on chosen exceptions such as tamper, failures, low battery etc (1 TTL pin) 11) Keep the hardware cheap, simple and easy to build on breadboard in case someone else wants it. 12) Write the embedded code in a structured manner to easily add/remove/modify modules. I'm probably missing a lot here, so any suggestions will be most welcome please. It's obvious this will take a lot of time but I'm hoping to slot it in-between all the other "salt mine" stuff. Fortunately I've used most of these modules in the past and therefore have the libraries for them. .
  4. This would be great! Currently I have versions 72.70C and 04.12. Could I update? If so, to which version? Where to be found? Is there a document describing the modified commands?
  5. I have 3 X 5kVA inverters in parallel to serve my day time loads that can reach 8kW. During night time the average load is approx. 1kW never exceeding 2 kW. I was wondering if it makes any sense to "sleep" 1 or 2 inverters during this time to save some power? Perhaps a light sensitive day/night switch with relay dry contacts (in parallel or in series as required) with the inverter ON/OFF switch for automatic control? I've done some tests manually switching them off and back on again and there seem to be no issues.
  6. Fazil, Is it mandatory to run AC and DC separately? What would be the advantage to fuse both battery terminals?
  7. Hi all, Thanks to so much good information on this forum, a lot of thinking, planning and building, I finally came online on Saturday. So far everything works pretty well. Eskom mains was turned off on Sunday and so far, no need even to run the generator. I am still finding my feet with all the settings and discovery of the best options but My system: 24 X JAR 375 W Mono's (8.8kWp) 3 X Axpert Type 4kW inverters in parallel (12kW) 7 X Narada NPFC100 Li-Fe-Po4 batteries (33.6kWh) 1 X Deutsz 15kVA generator Pic attached.
  8. sorry previous message not complete.... The Axpert spec. states: "Surge Capacity 2 X Rated Power for 5 seconds" which is 8kW @ 230 V meaning about 34 Amp max surge capability. (ignoring Power Factor) It remains to be seen if this accurate and if it will actually start motors without issues. (my guess.... probably not) The 3-phase borehole pump is targeted to get a VFD which (I understand) will "soft start" the motor thereby eliminating starting currents. Perhaps this is a solution for the other motors as well? The 3-phase diesel gen (15kVA) has no problem starting these motors but its got a heavy flywheel that stores lots of energy for peak demand surges.
  9. Thanks Javi and phil, The Axpert spec. states: "Surge Capacity 2 X Rated Power for 5 seconds"
  10. 1) Agreed 2) I think since the inverter sinewave is microprocessor generated, its an easy task for it to sync to another reference (in this case, the P2 inverter syncs (with 120 degree shift) to the P1 inverter and so on). For the 3-phase sync mode, there are additional connections (cables) required linking all 3 inverters for this purpose. (as well as the 3-phase unison shutdown scenario on any phase failure )
  11. Thanks guys, I've read the manual more intensely and confirmed the following: 1) If in 3-phase sync mode, all 3 will shut down if any one shuts down due to failure or overload (it makes sense). In case of failure, the remaining inverters can be temporarily re-configured to run 'stand-alone' until repaired/replaced. (obviously no 3-phase motors can be used during this time). The dead phase can be bridged to any of the remaining inverters as long as the load remains withing max limits. (the bridging has to be done on the dead side of the inverters-to-loads contactors to allow generator to supply 3-phase) 2) Found this pic showing different numbers of inverters on different phases showing 3-Parrallel on P1 and 2-Parallel on P2 and 1 alone on P3. It would suggest that the inverters won't mind unbalanced loads between the phases.
  12. Thanks phil.g00, Perhaps I've got it wrong but here's my thinking regarding the (3 x 1-phase inveters) vs (single 3-phase inverter): 1) The only 3-phase(ness) about the 3 inverters is that they are synced to produce 3 off single phases in 120 degree phase angles to each other. 2) Each inverter (I assume) should be able to supply different loads (up to 4kW each) on its own phase without concerning itself with the other 2 phases. 3) A 3-phase motor will add equal load to each inverter and function normally (provided all 3 phases in correct phase orders are present). 4) In essence therefore, these are 3 separate load circuits, sometimes with equal loads, sometimes not. 5) Each phase can later be beefed by adding (in parallel) another inverter. This need not be done on all phases simultaneously. My assumption 2) is where my concern lies. Can anyone confirm that the Axperts in 3-phase sync mode will allow this?
  13. Plonkster, I can get the Steca (axpert) for R10800 ExVAT. So that's R32k for 3 giving 12kW total available power. There's also some redundancy here since I can (temporarily) run single phase while doing repairs. The 3 phase gen can do the important 3 phase stuff - pump water etc. (BTW, I'm planning later to get a VFD for borehole pump with it' own PV's) I would also prefer a European type over Axpert. What inverter(s) would you suggest? DeepBass9 has a good point. I will re-look at that option. Some smaller motors can easily be converted to 1-phase. But I like the idea of having 3 inverters. Unlikely that 2 will fail simultaneously so I can get by until repairs done. With a single large inverter its total downtime if it fails.
  14. Thanks for all the good advice. Much appreciated. It seems I have a lot more to think about. SOME MORE BACKGROUND I live on a small holding east of Pretoria. There are 2 residences and both me and my tenant are self-employed with our workshops adjacent. We live and work here 24/7.I have no municipal services so I also need to pump and manage my own water supply, security, refuse et al. These are reasons for higher than average household usage. Water pumps, compressors, workshop tools are 3 phase (all motors have 3 phase dropout protection). The quite extensive power network is all wired 3 phase. All lighting is LED and 2 of 3 geysers are equipped with Evacuated Tube collectors (very seldom requiring electricity) . All security lighting is on day/nite switches set to minimum "on" time. Gate motors, electric fences etc. are already solar powered by their own local modules (simple DC battery charging - no inverters). The only item that can make a useful power reduction will be the 3rd geyser soon to get its own solar collector. Two years ago when I became "energy" conscious, I was using 2000kWh pm, so at this stage I've effectively halved my usage. It's the "diminishing returns" problem making it ever more difficult to reduce even further. The plan is to allow (for example) water pumping and compressor charging only during times with excess power from the PV array (after batteries charged) and/or when the generator has to run to make up shortfalls. This may be necessary daily. If so, the projected diesel cost will be around R700 pm. (not ideal but acceptable). Fortunaly the Deutz diesel seems in good nick and will hopefully last a few years during which time I can either extend the system or reduce energy usage.
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