January 23, 20233 yr Hi , First post here. I have recently had a system installed at my house. Nothing fancy but something to allow me to work when we have no power. So far the system does what I need but I have a question on configuration. I have 2 major options when configuration the inverter. Output source priority selection 1. SbU. Solar energy provides power to the loads as first priority. Solar and battery will provide power to the load. When the batter drops below a configured voltage it will switch to grid. 2. Uti. Solar use used when the grid is not available. Grid charges the battery. Using the SbU mode: The problem with this and I found it out the other day. During the day it worked perfectly. We hit 7pm Sun was gone and the battery started to get used. At 8am load shedding hit and by that stage the battery was around 20%. The utility would only charge once the voltage was low enough on the batteries. What happened though was the battery hit 10% during load shedding and then the utility was not able to charge the batteries and we had to wait for load shedding to finish. Using Uti mode: This works fine. I have configured the inverter to charge the batteries with solar however, if there is excess solar the inverter still uses utility to power the load. The only time solar is used is when there is no Utility power available. I did some tests and set the voltage on the battery in the inverter to not go below 26.5V so the SbU mode works and then if the battery goes below 26.5V Utility power kicks in to charge it and serve the current load. During the day the battery and load are both served from the Solar power. Does anyone know of a better way if possible to do this. I am using a MUST Inverter PV1800 3kw
January 23, 20233 yr I'm considering purchasing a similar model for my own backup needs (Specifically the PV18-3024VPM). I've been studying the user manual as part of my research. I interpret the "output source priority" options as follows: SUB = solar - utility - battery SBU = solar - battery - utility SOL = solar only UTI = utility only Based on this, I reckon you actually want SUB - since you don't want to use battery if the grid is available? SUB should use solar first, if that's not available, go to utility, and if that's not available then battery. My interpretation of the SUB setting description is that it'll draw as much solar as it can, if the loads is more than what solar can give, it'll draw from the grid, and if the grid is not available then it'll draw from the battery. This way you will always use your panels to provide power to the home when the sun's out. In addition to the above, you have two other important settings: "Solar Supply Priority" (05) I reckon for this one, you need to set it to LBU (load-battery-utility). If the battery level is lower than the setpoint in setting 20, then use solar to charge the battery. I interpret "If the battery voltage is higher than the setting point in program 20, the solar energy will supply to the load or recharge the battery." to mean that it'll charge the battery at whatever amperage it needs, and the rest will go to the load. In addition to this, I think you can change setting 20 to something higher than default. Set it to maybe 70% of your battery SOC voltage? That way, you will never drain the battery below 70% IFF the grid is available and you have no sun. You'll only dip into your reserves if the grid is not available during loadshedding. "Charger Source Priority" (10) Here I think SNU (solar-and-utility). You will charge the battery using both solar and grid (same as setting 05). I think bottom line is the battery is there for a backup. Not to be used as part of your regular daily usage. Our grid is unpredictable, and you want to make sure you have battery available when you need it, and not draw from the batteries when you can avoid it (when the grid is available).
January 24, 20233 yr Author 17 hours ago, suds7162 said: SUB = solar - utility - battery SBU = solar - battery - utility SOL = solar only UTI = utility only Thank you for your input. I 100% agree with you on your interpretation however my inverter does not have the SUB option. Only the other 3 options.
November 26, 20232 yr I have recently had the same MUST 3kw inverter installed. I get the impression the installer (qualified registered electrician) is still on a learning curve, but I am starting from zero and trying to get the menu settings right. Twice the battery has overloaded (error 3) and once has been completely flat -0%. Surely this is damaging the battery. How to I set it not to go above or below a certain capacity? My inverter is only connected to certain circuits on the DB board (all the lights) and a few specially installed electric sockets, supposed to keep the fridge and house alarm going every day during load shedding, plus one or two small loads eg TV. The solar panels have been very successfully charging the battery every sunny day, but at night, between load shedding, the grid doesn’t kick in to recharge the battery. There must be some incorrect setting on the inverter menu. Please help this not -electrically-knowledgeable senior lady.
February 11, 20242 yr I've got the same 3kw inverter and recently got panels installed, also went for gel to a lithium battery. I setup the output source priority to SOL. I set program 20 to 26V and default on program 21. So my system seems to be behaving, the grid disconnects when the panels can handle the load. If it does not, it connects battery. If the battery voltage falls to 26V the grid kicks in and charges everything. So far most of the day I'm drawing 0 from the grid. I did test the SBU option but I didn't set the parameters of the program 20 and 21 properly and drained the batteries through the night over a stage 6 load shedding. Using Uti I'm not saving during the day with the panels and constantly charges. So I've ruled this setting out for my setup. I would say that this system has saved us endless power outage hassles, but I do feel I should have gone with a 5KW inverter instead just to handle loads a bit better from multiple appliances. However, I've been quite happy and would appreciate any advice or changes that work for you on this MUST inverter.
February 13, 20242 yr SilverFox, is it the 1800-3024VPM you have? I have that and it doesnt behave as yours does. If grid is available it will always be on bypass while solar charges the battery. I'm on SOL mode now, but have tried UTI and SbU. For Setting 5 I've tried both LBU (solar goes to loads and then batteries if excess power) and BLU (solar priority to charge batteries). Both cases Utility should be last resort. Setting 20 is at 26.1V Setting 21 is at 27.2V (whats the default I don't feel like resetting right now?) Could this be the problem for me? Veronica there are definitely some settings you can change to help - although I feel some of these inverters have some bugs and you may have a dud. Some will reach float voltage and not continue charging. Some may behave like mine and not use solar on a sunny day when grid is available. Try changing setting 14 to USE, 17 to 28.6 and 18 to 26.7. This should be fine for LiFePO4 batts. If you battery capacity is 2.5kWh or below I'd recommend setting 11 to "25", and 13 to "20". This is charge current.
May 9, 20242 yr On 2023/01/23 at 5:03 PM, roboza said: Hi , First post here. I have recently had a system installed at my house. Nothing fancy but something to allow me to work when we have no power. So far the system does what I need but I have a question on configuration. I have 2 major options when configuration the inverter. Output source priority selection 1. SbU. Solar energy provides power to the loads as first priority. Solar and battery will provide power to the load. When the batter drops below a configured voltage it will switch to grid. 2. Uti. Solar use used when the grid is not available. Grid charges the battery. Using the SbU mode: The problem with this and I found it out the other day. During the day it worked perfectly. We hit 7pm Sun was gone and the battery started to get used. At 8am load shedding hit and by that stage the battery was around 20%. The utility would only charge once the voltage was low enough on the batteries. What happened though was the battery hit 10% during load shedding and then the utility was not able to charge the batteries and we had to wait for load shedding to finish. Using Uti mode: This works fine. I have configured the inverter to charge the batteries with solar however, if there is excess solar the inverter still uses utility to power the load. The only time solar is used is when there is no Utility power available. I did some tests and set the voltage on the battery in the inverter to not go below 26.5V so the SbU mode works and then if the battery goes below 26.5V Utility power kicks in to charge it and serve the current load. During the day the battery and load are both served from the Solar power. Does anyone know of a better way if possible to do this. I am using a MUST Inverter PV1800 3kw Did you find a response to this issue. Having exact same problem with my MUST Inverter 3KVA. No SUB setting.
May 16, 20242 yr There are a few things to address here: 1. Unfortunately, it seems the MUST inverters are also plagued with the "premature float" bug, as in Axpert inverters. So you may be experiencing batteries thahaven'nit fully charged from solar during sun hours, a d therefore not lasting as long into the night. I have played around with settings, but haven't had much success. A partial (not ideal) solution is to set the battery type as LI instead of USE. You can still change float and bulk voltages (set battery type to LI and then change voltage settings). It partially solves the problem, because the charging strategy is different: It charges up to float voltage first, holds this voltage for a while, then charges up to bulk. So it doesn't prematurely float. But there are downsides: First, being that while the lower float voltage is reached, it tends to hold it there for a certain time, taking less power from PV. Second, when it reaches bulk, it doesn't stop charging, it just keeps the battery at the voltage (forever ?) as long as solar power is sufficient. But if you charge from solar only and have conservative float/bulk settings, I think it won't harm the battery too much. Lifepo4 doesn't like to be at high SOC for a long time, but since we are charging from solar, it shouldn't be more than a few hours (depending on how much solar you have). 2. Check setting #28, make sure it's enabled. This will allow you to make the most of your PV production. 3. I find setting #5 to be misleading: Its called "solar supply priority", but at least from my observations, it's not really prioritizing. It simply relies on different voltage thresholds (either setting #20 or #21, in regards to LBU/BLU respectively). So basically you need to choose how much you want to drain your battery, but via voltage settings. When in SBU mode, let's say you set #21 to 26.6v and setting #5 to BLU, it will drain the battery (when no solar) untill around 80% SOC (for Lifepo4) and then start powering loads from the grid. The next day, when solar power is available, it will continue powering the loads from the grid, until battery has reached setting #21. So in short, I find it hard to maximize PV usage with the MUST inverters.
May 17, 20242 yr 18 hours ago, meetyg said: There are a few things to address here: 1. Unfortunately, it seems the MUST inverters are also plagued with the "premature float" bug, as in Axpert inverters. So you may be experiencing batteries thahaven'nit fully charged from solar during sun hours, a d therefore not lasting as long into the night. I have played around with settings, but haven't had much success. A partial (not ideal) solution is to set the battery type as LI instead of USE. You can still change float and bulk voltages (set battery type to LI and then change voltage settings). It partially solves the problem, because the charging strategy is different: It charges up to float voltage first, holds this voltage for a while, then charges up to bulk. So it doesn't prematurely float. But there are downsides: First, being that while the lower float voltage is reached, it tends to hold it there for a certain time, taking less power from PV. Second, when it reaches bulk, it doesn't stop charging, it just keeps the battery at the voltage (forever ?) as long as solar power is sufficient. But if you charge from solar only and have conservative float/bulk settings, I think it won't harm the battery too much. Lifepo4 doesn't like to be at high SOC for a long time, but since we are charging from solar, it shouldn't be more than a few hours (depending on how much solar you have). 2. Check setting #28, make sure it's enabled. This will allow you to make the most of your PV production. 3. I find setting #5 to be misleading: Its called "solar supply priority", but at least from my observations, it's not really prioritizing. It simply relies on different voltage thresholds (either setting #20 or #21, in regards to LBU/BLU respectively). So basically you need to choose how much you want to drain your battery, but via voltage settings. When in SBU mode, let's say you set #21 to 26.6v and setting #5 to BLU, it will drain the battery (when no solar) untill around 80% SOC (for Lifepo4) and then start powering loads from the grid. The next day, when solar power is available, it will continue powering the loads from the grid, until battery has reached setting #21. So in short, I find it hard to maximize PV usage with the MUST inverters. Yea if you make the float voltage higher then the chances of losing solar production is less I just change the profile for charging to be only solar and thus the batteries won't be kept high float for long as solar dies down it won't float from utility
May 17, 20242 yr Most of the problems related to SBU voltages Are related to lifepo4 batteries having a rather flat charge/discharge curve ie you experience either one of the the two Set voltage low and have more savings from solar but bump up against low voltage shutdowns (in sedding) Or Set voltage higher and inverter will switch back to grid way to soon limiting solar savings The best solution to this off-grid axpert inverters Is a cheap raspberry pi With either solarassistant/SMH That actually uses math to determine the state of charge ignoring voltage And uses that to determine the switch to grid or battery Making keeping a reserve for shedding easier Can also do remote management in case the weather changes or shedding stage changes It really is a game changer I have a few profiles set to intervene remotely Edited May 17, 20242 yr by Leondavibe
July 20, 20241 yr I have Techfine Inverter..and I found that LBU doesnt work when I use SBU mode.. so when Battery is on charging mode , all power from solar will be used for charing battery and house load is taken 100% from Grid.( while I actually expect LBU to works so PV will power Load first. before charging Battery )
November 10, 20241 yr I just bought a new Must 3kv inverter. what is happening is the inverter is coming on every few minutes. The battery light is flashing all the time. i have tried different settings. i need some help.
November 11, 20241 yr On 2024/07/20 at 8:21 PM, andy darwin said: I have Techfine Inverter..and I found that LBU doesnt work when I use SBU mode.. so when Battery is on charging mode , all power from solar will be used for charing battery and house load is taken 100% from Grid.( while I actually expect LBU to works so PV will power Load first. before charging Battery ) normally there is two different settings regarding this the one deals with the priority of solar ie load or battery fisrt and then grid feed and then there is a different setting that determines the priority for load ie grid/solar/battery so you gottan check which menu item deals with it output source priority normaly it is something like UTI/SBU/SOL uti is eskom SBU will use solar and battery until the back to grid voltage is hit and then use eskom and SOL is solar only so not sure if it switch inverter off or switch to eskom if battery is flat don't use it and the other setting has charge sopurce priority
November 11, 20241 yr On 2024/11/10 at 10:10 AM, pete the man said: I just bought a new Must 3kv inverter. what is happening is the inverter is coming on every few minutes. The battery light is flashing all the time. i have tried different settings. i need some help. the battery light flashing isn't abnormal as any charhing normally cause that i think ie float also counts as charhing so the battery is probably always charging or floating what do you mean it is coming on every few minutes some inverters have a powersave mode the inverter goes into standby if load is low enough and comes on if some load is detected could maybe be that menu item 29 is for that SdS is disabled and SEn is enabled what battery do you have gel or lithium, do you have solar and what is the voltage settings and charge priority menu items are 14 is battery type 17/18/19 is the charge/float/cut-off voltages 10 is charge source priority Edited November 11, 20241 yr by Leondavibe more info
November 11, 20241 yr 2 hours ago, Leondavibe said: the battery light flashing isn't abnormal as any charhing normally cause that i think ie float also counts as charhing so the battery is probably always charging or floating what do you mean it is coming on every few minutes some inverters have a powersave mode the inverter goes into standby if load is low enough and comes on if some load is detected could maybe be that menu item 29 is for that SdS is disabled and SEn is enabled what battery do you have gel or lithium, do you have solar and what is the voltage settings and charge priority menu items are 14 is battery type 17/18/19 is the charge/float/cut-off voltages 10 is charge source priority by coming on i mean the fans come the inverter and they run for a while and the switch off. that happens every 5 min or so. Today switch the pv panels off and the fans have not come on. On 2023/01/23 at 5:03 PM, roboza said: Hi , First post here. I have recently had a system installed at my house. Nothing fancy but something to allow me to work when we have no power. So far the system does what I need but I have a question on configuration. I have 2 major options when configuration the inverter. Output source priority selection 1. SbU. Solar energy provides power to the loads as first priority. Solar and battery will provide power to the load. When the batter drops below a configured voltage it will switch to grid. 2. Uti. Solar use used when the grid is not available. Grid charges the battery. Using the SbU mode: The problem with this and I found it out the other day. During the day it worked perfectly. We hit 7pm Sun was gone and the battery started to get used. At 8am load shedding hit and by that stage the battery was around 20%. The utility would only charge once the voltage was low enough on the batteries. What happened though was the battery hit 10% during load shedding and then the utility was not able to charge the batteries and we had to wait for load shedding to finish. Using Uti mode: This works fine. I have configured the inverter to charge the batteries with solar however, if there is excess solar the inverter still uses utility to power the load. The only time solar is used is when there is no Utility power available. I did some tests and set the voltage on the battery in the inverter to not go below 26.5V so the SbU mode works and then if the battery goes below 26.5V Utility power kicks in to charge it and serve the current load. During the day the battery and load are both served from the Solar power. Does anyone know of a better way if possible to do this. I am using a MUST Inverter PV1800 3kw
November 11, 20241 yr 2 hours ago, Leondavibe said: the battery light flashing isn't abnormal as any charhing normally cause that i think ie float also counts as charhing so the battery is probably always charging or floating what do you mean it is coming on every few minutes some inverters have a powersave mode the inverter goes into standby if load is low enough and comes on if some load is detected could maybe be that menu item 29 is for that SdS is disabled and SEn is enabled what battery do you have gel or lithium, do you have solar and what is the voltage settings and charge priority menu items are 14 is battery type 17/18/19 is the charge/float/cut-off voltages 10 is charge source priority Members 5 Author Posted 1 hour ago MUST 3KVA AMP135A SOLAR CHARGING 100 A MAX PV OPEN CIRCUIT V 400 VDV 2 X 550 WATT PANELS BATTERY 25.6V N VOLTAGE 25.6V USEABLE ENERGY 3.07KWH CHARGE CURRENT 30A DISCHARGE C 50A VOLTAGE RANGE 21.6-29.2V 1. SOL 2 APL 3 230 4 50.0 5. LBU 6 6YE 7 LFD 10 SNU 11 100 13 60A 14 LI 17 28.6 18 26.7 19 20.4 20 23V 21 26.4 22. PTD 28 SBE 30 EEN 31 Eu 33 60 34 120 35 30d 36 AdS 37 uol 38 20% 39 95% 41 SEL 59 SEN 60 22.0 V
November 12, 20241 yr 22 hours ago, Leondavibe said: the battery light flashing isn't abnormal as any charhing normally cause that i think ie float also counts as charhing so the battery is probably always charging or floating what do you mean it is coming on every few minutes some inverters have a powersave mode the inverter goes into standby if load is low enough and comes on if some load is detected could maybe be that menu item 29 is for that SdS is disabled and SEn is enabled what battery do you have gel or lithium, do you have solar and what is the voltage settings and charge priority menu items are 14 is battery type 17/18/19 is the charge/float/cut-off voltages 10 is charge source priority hi. so the problem the settings between the panels and battery. my settings are 1. uti 05. default lbu 10. default snu 19. 20.4 20. 23 21. 26.4 29.sbe the battery is a lithium Ion. panels are 2 x 550 watt i dont know what other info you need. regards
November 13, 20241 yr On 2024/11/11 at 6:25 PM, pete the man said: by coming on i mean the fans come the inverter and they run for a while and the switch off. that happens every 5 min or so. Today switch the pv panels off and the fans have not come on. ok the fans ramp up based on solar output that is normal normaly the fans are quiet when the load is being powered from eskom and only ramps up when load is higher, their fan speed is also linked to solar output, so if the solar output goes up so does the fan speed, so nothing to worry about, when close to full the bms can sometimes stop charging as one of the cells peak and if the balancing drops voltage then it starts charging again hence kicking in and out the other possibility is if the charge voltage is a bit lower the inverter can switch to float mode prematurely, then as the voltage settles the voltage can drop below the float setting which triggers another charge session if you are sure the battery is full which will probaly be the case with the voltage you mentioned, and your battery maybe rests at a slightly lower voltage lowering the float voltage a bit to match its natural resting voltage you can get out of the constant triggering of charge cycles or maybe lift the charge voltage higher closer to the max if the battery cables are very thin or long it can also cause a voltage drop, so then the battery isn't really at full voltage and the inverter thinks it is, once it stops charging the voltage settles and it sees the battery isn't full and thus starts charging again normally in float mode the voltage isn't affected that much since the amps are very low, and thus it may get more accurate reading while floating and not while charging i would try the charge voltage closer to the 29.2 and see what it does, can then also set the load to be from eskom and set the float very low to allow the full battery to rest without triggering another charging cycle see what voltage it settles at then set your float to that voltage
November 13, 20241 yr On 2024/11/12 at 2:41 PM, pete the man said: hi. so the problem the settings between the panels and battery. my settings are 1. uti 05. default lbu 10. default snu 19. 20.4 20. 23 21. 26.4 29.sbe the battery is a lithium Ion. panels are 2 x 550 watt i dont know what other info you need. regards ok so the system isn't foccused on savings as load is run from eskom menu item 1 UTI, when solar is doing well can switch menu item 1 to SBU then load will be powered from solar to save more power and excess solar will charge battery, and then switch 1 to UTI after hours again if you want to keep battery rerserve for eskom outages, if you want to save as much on power as you can , you can then leave it on SBU for a portion of the night to empty batteries to accept more solar next day, but then the charging priority option SNU/CSO/SOL has to be on SOL ie only charge from solar, it will leave the bvattery where it is at when you switch back to UTI and apply no charging until solar kicks in next day SNU charge with Solar and eskom at the same time if you have chaging amps set to 30A and the solar produces 20A charging then the other 10A will come from eskom CSO will charge only with solar if available, once solar goes to zero it will charge further with eskom the problem is even if only 10w it sees it as charging from solar and eskom doesn't help, if you have a breaker on panels flipping it off will force eskom charge on this setting, or you have to set to SNU when you know shedding is coming SOL will only charge from solar and once solar is gone battery is left to settle wherever it is at and only start charging when solar is avialable again UTI load powered from eskom and SOLAR is left to charge battery only (unless youir inverter is hybrid and can mix eskom and solar most axpert types aren't) SBU load will be powered from Solar then battery and if it hits the switch back to grid voltage it will use eskom SOL on menu item 1 will only use Solar/battery and no eskom so you have to play with both the UTI/SBU/SOL and the SNU/CSO/SOL setting to find the mix you want Edited November 13, 20241 yr by Leondavibe
November 21, 20241 yr Does anyone know how to connect dyness battery to must inverter via cam bus? Which setting should I use in menu 41? Or does anyone know list of protocols that I can choose from in menu 41?
December 2, 20241 yr Hi i hope someone can help i have a Must 3kw 100Amp 24v MPPT Solar Hybrid Inverter PV1800 PV18-3024 Eco inverter. I have set all the settings to what i believe is correct but i cannot get the invetrter to exit the settings menu. If i scroll past setting 60 it goes to setting 01 and not to 00 as my other musk inverter. TIA
December 3, 20241 yr 20 hours ago, Jarrod said: Hi i hope someone can help i have a Must 3kw 100Amp 24v MPPT Solar Hybrid Inverter PV1800 PV18-3024 Eco inverter. I have set all the settings to what i believe is correct but i cannot get the invetrter to exit the settings menu. If i scroll past setting 60 it goes to setting 01 and not to 00 as my other musk inverter. TIA Press the menu button until you see it change.
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