October 17, 20223 yr 4 minutes ago, Leog said: What i find hard to believe is that when load is low, it consumes most of the energy from Utility. OK, so I have found that the MAX-E 11kW has got built in functionality that will divert to grid rather than PV when the load is too small. We could be running into something similar, but with mine running almost constantly above 2kW I don't really get time to test it. If this is the case then yes, that is expected behavior. I had a dude shouting and screaming that his unit is a dud, meanwhile his load was so low that the MAX-E didn't bother using the MPPT board. It was only once we pushed his load above a threshold that it started pulling from PV.
October 17, 20223 yr Author 3 minutes ago, Psy said: OK, so I have found that the MAX-E 11kW has got built in functionality that will divert to grid rather than PV when the load is too small. We could be running into something similar, but with mine running almost constantly above 2kW I don't really get time to test it. If this is the case then yes, that is expected behavior. I had a dude shouting and screaming that his unit is a dud, meanwhile his load was so low that the MAX-E didn't bother using the MPPT board. It was only once we pushed his load above a threshold that it started pulling from PV. Yeap this is exactly what i am witnessing also. My load is <300w 20/24 hours of the day. That possibly means i will make no electricity savings at all these hours, instead i will consume more due to inverter being powered by Utility mostly. Only when i have high load then i will be making any savings. This assumption really sucks!
October 17, 20223 yr And this is where a battery would be able to fill in... Not only would it act as a load to charge, engaging the MPPT, but you can then use it for backup... Otherwise, it may be worth adding something small onto the circuit that will put usage over the threshold (Spotlight or something that's a couple hundred watts). To be fair, @Coulomb may have an update or patch for the software to override this feature but it isn't something I haven't had to really look into. In the one time I had this issue we just swapped the 11kW for 2 5,6kW and the load was just enough to make them work, problem solved...
October 17, 20223 yr Author 3 minutes ago, Psy said: And this is where a battery would be able to fill in... Not only would it act as a load to charge, engaging the MPPT, but you can then use it for backup... Otherwise, it may be worth adding something small onto the circuit that will put usage over the threshold (Spotlight or something that's a couple hundred watts). To be fair, @Coulomb may have an update or patch for the software to override this feature but it isn't something I haven't had to really look into. In the one time I had this issue we just swapped the 11kW for 2 5,6kW and the load was just enough to make them work, problem solved... Yeap i get the battery is the next crucial addition to the system and i have to plan it faster it seems. Though from my research with batteries it cannot blend PV and AC if needed, it switches to AC if PV+Battery isn't enough. Correct?
October 17, 20223 yr My Mecer Axpert MK IV blends AC, Solar and Battery perfectly. Edited October 17, 20223 yr by Douw G. Gerber
October 17, 20223 yr Author 6 minutes ago, Douw G. Gerber said: My Mecer Axpert MK IV blends AC, Solar and Battery perfectly. This is good to know i suppose mine should do the same! Is this SUB setting right? Also Nice graph! What is it? HomeAssistant? I see you also have high Grid usage.
October 17, 20223 yr 3 hours ago, Leog said: I did change this 25 setting to ON after your suggestion. Also changed some battery related values, but i am sure it doesn't matter overall. I tried again today to open the inverter and as soon as i put a load before it starts beeping it worked. 😂 Not confident it won't do it again. Dang this was unexpected! Now i am trying to find out the high Utility consumption. My PV array is 6x405W JaSolar in series. Time was around 15.30 afternoon ( in 3hours sun has set) House load -> 200w -> Utility 240 -> Pv 60 ( inverter consumption around 100w?) House load -> 1000w -> Utility 150 -> Pv 950 House load -> 2400w -> Utility 950 -> Pv 1650 (inverter consumption 200w?) I am measuring the Utility Watts with a Shelly 3EM wifi meter. What i find hard to believe is that when load is low, it consumes most of the energy from Utility. Also on high load the inverter seems to be having a consumption close to 200w (give or take). Are these findings correct? Will try to put a usb otg to dump the settings and logs later today. Please note that it is very important that if you measure the grid side power that you must ensure the meter reads watts and not va. The reason is the current lags the voltage with a number of degrees. I measured over 3A current (over 600VA) while the actual watts is only around 100 watts. The 100watts minimum just comes with the gridtied territory. It is a mechanism that voltronics use to stabilise grid interaction and tries to minimise inadvertant exporting of power when load is minimum.
October 17, 20223 yr Author 24 minutes ago, BritishRacingGreen said: Please note that it is very important that if you measure the grid side power that you must ensure the meter reads watts and not va. The reason is the current lags the voltage with a number of degrees. I measured over 3A current (over 600VA) while the actual watts is only around 100 watts. The 100watts minimum just comes with the gridtied territory. It is a mechanism that voltronics use to stabilise grid interaction and tries to minimise inadvertant exporting of power when load is minimum. Oh that is why my multimeter was reading something like 3.25a in AC in. But actual power was a Indeed somewhere around 100w when I made the math from the Shelly power meter which takes into account the Power factor. At night the inverter is drawing 50-60w being in bypass mode as Pv has stopped completely. Guess this is the absolute minimum.
October 18, 20223 yr Author Writing a summary here for helping others on the baterryless feature of the MKS IV. It doesn't start immediately, beeps sometimes and if you leave it with load for 2-3 min it starts giving output ( no clue why this happens). With around 210v indeed its working batteryless together with AC IN fine. Went through the night with inverter going into bypass mode essentially providing the load from ac in completely. (average consumption of inverter around 50w), in the morning mppt engaged fine on its own. When PV is available it does have a minimum threshold of ac and pv it mixes. If the load is low < 300w (haven't found exactly) then around 220-240w come from the AC IN and rest from the PV. As soon as you put a 1000-2000w load then PV engages and ac IN load goes down to 100-150w and rest comes from PV. Load surges are first being supported by AC IN until mppt ramps up, then the load transfers to PV. Takes about 3-4seconds No lights are flickering nor other issues for now. My whole house is almost** supplied by the Axpert. Will come back after some time to report if running it batteryless has any impact at all overall. ** Except ceramic stove, well pump and heat geysers ( i have gas heater) Edited October 18, 20223 yr by Leog
October 18, 20223 yr 7 hours ago, Leog said: Will come back after some time to report if running it batteryless has any impact at all overall. Perfect!
December 7, 20223 yr Author And the battery got installed! No more annoying beeping. In the course of 2 months, 3-4 times the inverter would start beeping around dawn giving no output. Still a mystery. But with the battery installed all looking much better. Jk-bms + 16x105 EVE grade A from Nkon. Super happy with the result. Though i am finding it hard to find the correct settings for the Battery parameters. So if anyone can comment. Currently i have: Battery Cut off voltage 47v Back to grid voltage 48v Back to discharge 54v Float voltage 55v Bulk voltage 56v Max charging current 30A Does this look ok? Goal is to minimize my electricity bills. Prolonging battery life is second priority though i am not planning to go above 3.5v per cell or below 3v per cell.
December 7, 20223 yr 55 minutes ago, Leog said: And the battery got installed! No more annoying beeping. In the course of 2 months, 3-4 times the inverter would start beeping around dawn giving no output. Still a mystery. But with the battery installed all looking much better. Jk-bms + 16x105 EVE grade A from Nkon. Super happy with the result. Though i am finding it hard to find the correct settings for the Battery parameters. So if anyone can comment. Currently i have: Battery Cut off voltage 47v Back to grid voltage 48v Back to discharge 54v Float voltage 55v Bulk voltage 56v Max charging current 30A Does this look ok? Goal is to minimize my electricity bills. Prolonging battery life is second priority though i am not planning to go above 3.5v per cell or below 3v per cell. Yes it looks good, the performance is heavily dependant on well torqued connections. Are you going to house it in enclosure, or at least have a protective cover on the top? Well done 👌 is that 120Ah cells? What bms you using? Dont stress if you do encounter bms protection on max cell v overshoot. When you keep the max charge voltage reasonably low, over time the cells gets well balanced and these fault will vanish. There is initially always an outlier cell that may cause problems. How are you going to read the SOC? From the BMS Bluetooth app? Edited December 7, 20223 yr by BritishRacingGreen
December 7, 20223 yr Author 27 minutes ago, BritishRacingGreen said: Yes it looks good, the performance is heavily dependant on well torqued connections. Are you going to house it in enclosure, or at least have a protective cover on the top? Well done 👌 is that 120Ah cells? What bms you using? Dont stress if you do encounter bms protection on max cell v overshoot. When you keep the max charge voltage reasonably low, over time the cells gets well balanced and these fault will vanish. There is initially always an outlier cell that may cause problems. How are you going to read the SOC? From the BMS Bluetooth app? These are EVE LF105 cells, Grade A as per Seller (Nkon is reputable europe battery seller) I torqued with hand. Toughest was the small screws that bolt on the cells. These are miniature philips head. Had to buy a hydraulic press for the fittings as it gives me peace of mind on the connections. Also added plastic sheets in between the cells for added protection. Compressed only by some duct tape, not going the heavy compression route. Battery went into heavy duty plastic box with lid. Wiring is 4awg with 160A NH00 Fuse. The bms is the JK-BMS 100A version with bluetooth and 0.6A balancer integrated. The app in my phone is awesome and i see everything i need for the battery. Tested with my Uni-T210E bms is accurate. I do see the first cell always being an outlier , it just keeps having lower voltage. And the balancer keeps propping it up. In theory with bulk charging at 56v and float at 55v i wont see ever the OVP bms protection kick in as it is at 3,65v (58.4v). Nice thing about this BMS, you can put the battery connection without sparks or the need to precharge. Once you have everything wired up you can enable discharge from the app! Edited December 7, 20223 yr by Leog
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