PsyCLown Posted March 3 Share Posted March 3 Hey all! So something has been bugging me about these Luxpower inverters for a while now, today I finally decided to investigate a bit further and this seems to have confirmed my suspicions and its quite frustrating... I have a voltage protection device connected before my inverter circuit breakers (where Eskom gives power to the inverters). The voltage protection device allows me to see the voltage & current in realtime. I noticed a couple months ago that even when the load for the house is being carried by PV or if I am running on PV & Batteries, there is always current draw being displayed on the voltage protection and this current draw figure varies from time to time and is anywhere from 2.8A to 3.8A when there should be no draw from Eskom. So I decided to stop being lazy and investigate further. I removed the cover of my DB board and used my clamp meter to assist me. Now I do not expect either the voltage protection device or my clamp meter to be 100% accurate but I do expect them to give me a fairly accurate reading. I understand the clamp meter is probably less accurate in this instance. So before I started this test, I ensured that my inverter settings were as such to force the inverter to use PV & Battery only, no grid usage as per the below screenshot. So below you can see a comparison of the clamp meter & voltage protection device both detecting current. One reads 3,9A and the other 4,5A - this confirms to me that there is definitely current flowing So I gave the Luxpower inverters the benefit of the doubt, maybe the voltage protection device is somehow consuming the power... although it seems a bit odd, lets try confirm this. So I turned off the breakers giving Eskom power to both my inverters and suddenly there was no usage displayed on both the voltage protection device & my clamp meter as can be seen below. Now this does concern me and puzzles me a bit, I can understand that the Luxpower does not have an external CT coil and you have the CT coil offset to assist with calibrating it. By default mine was on 20W, I adjusted this (after I turned on the breakers, so my inverter had grid) to 199W and then to -199W and I did not see much (if any) difference to the readings on the voltage protection device or the clamp meter. If we call it an average of 3,2A, since this is basically 24/7 that usage adds up quickly. 3,2A x 230v = 736W 736W x 24 hours = 17,66kWh per day 17,66kWh x 30 days = 529,8kWh in a 30 day month... Its a significant amount. To be fair, this would not all be offset by solar anyways, there might only be around 7 hours in a day where this usage is offset by solar. 3,2A x 230v = 736W 736W x 17 hours = 12,51kWh per day 12,51kWh x 30 days = 375,3kWh in a 30 day month... A potential loss of 154,5kWh per month because of this. At around R4 per kWh on the higher tier, this works out to around R618 per month. So now, does anyone know why the Luxpower does this? Why does it draw soo much from the grid when the loads should be covered by PV or PV & Battery and it should not be drawing from the grid? Also does anyone know whether the same is applicable to the Sunsynk/Deye inverters & Solis inverters? Quote Link to comment Share on other sites More sharing options...
eugenedp Posted March 3 Share Posted March 3 (edited) That is concerning. I assume that the interface shows no current draw from the supply? I have not checked mine, I know it draws momentarily from the Eskom side when a large inductive load starts - my battery can only supply 2.4kw. But I have not seen a continuous draw, because I never suspected one or checked for one. Edited March 3 by eugenedp Spelling Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted March 3 Share Posted March 3 (edited) 20 hours ago, PsyCLown said: Hey all! So something has been bugging me about these Luxpower inverters for a while now, today I finally decided to investigate a bit further and this seems to have confirmed my suspicions and its quite frustrating... I have a voltage protection device connected before my inverter circuit breakers (where Eskom gives power to the inverters). The voltage protection device allows me to see the voltage & current in realtime. I noticed a couple months ago that even when the load for the house is being carried by PV or if I am running on PV & Batteries, there is always current draw being displayed on the voltage protection and this current draw figure varies from time to time and is anywhere from 2.8A to 3.8A when there should be no draw from Eskom. So I decided to stop being lazy and investigate further. I removed the cover of my DB board and used my clamp meter to assist me. Now I do not expect either the voltage protection device or my clamp meter to be 100% accurate but I do expect them to give me a fairly accurate reading. I understand the clamp meter is probably less accurate in this instance. So before I started this test, I ensured that my inverter settings were as such to force the inverter to use PV & Battery only, no grid usage as per the below screenshot. So below you can see a comparison of the clamp meter & voltage protection device both detecting current. One reads 3,9A and the other 4,5A - this confirms to me that there is definitely current flowing So I gave the Luxpower inverters the benefit of the doubt, maybe the voltage protection device is somehow consuming the power... although it seems a bit odd, lets try confirm this. So I turned off the breakers giving Eskom power to both my inverters and suddenly there was no usage displayed on both the voltage protection device & my clamp meter as can be seen below. Now this does concern me and puzzles me a bit, I can understand that the Luxpower does not have an external CT coil and you have the CT coil offset to assist with calibrating it. By default mine was on 20W, I adjusted this (after I turned on the breakers, so my inverter had grid) to 199W and then to -199W and I did not see much (if any) difference to the readings on the voltage protection device or the clamp meter. If we call it an average of 3,2A, since this is basically 24/7 that usage adds up quickly. 3,2A x 230v = 736W 736W x 24 hours = 17,66kWh per day 17,66kWh x 30 days = 529,8kWh in a 30 day month... Its a significant amount. To be fair, this would not all be offset by solar anyways, there might only be around 7 hours in a day where this usage is offset by solar. 3,2A x 230v = 736W 736W x 17 hours = 12,51kWh per day 12,51kWh x 30 days = 375,3kWh in a 30 day month... A potential loss of 154,5kWh per month because of this. At around R4 per kWh on the higher tier, this works out to around R618 per month. So now, does anyone know why the Luxpower does this? Why does it draw soo much from the grid when the loads should be covered by PV or PV & Battery and it should not be drawing from the grid? Also does anyone know whether the same is applicable to the Sunsynk/Deye inverters & Solis inverters? Can you perhaps confirm that you did not have the setting on to take load together via PV and AC? Did you ensure you did not have hybrid enabled? I can assure you that another SNA I looked at did not use even 80W from the grid by looking at the prepaid meter use. Based on the measurements it could be possible that you are exporting the 3.9-4.5A and the moment you switched off the grid input to your Inverters there is no path to export power. Both the tools you used for measuring just reads amps and doesn't know if it is importing or exporting. Further you are measuring VA. The Watts could be a lot less although it does not matter much for the purpose of the test. PF is important to take into account on AC circuits. Just a thought based on what you are describing. A good power meter indicating direction will give a clear answer. Even the prepaid does not always give a direction of power measured. Perhaps someone with the same inverter can indicate if the grid use showing zero as per your picture if it will show a negative value during a period one is exporting in hybrid mode. I am reasonable sure that a friend with only 4 panels fitted will see this massive grid use you are reporting. If it was me that had to measure the self use of the inverters I would not run a load of 7.5 kW that exceeds the PV value and to call on the battery to assist. I will for the duration of the measurements run at a very low load or better still with no load apart real essentials like WiFi for the dongle. Also many members will be able to confirm that the grid use(self) from a Solis/Suns/Deye is quite a bit below 100W. Edited March 4 by Scorp007 Spelling Quote Link to comment Share on other sites More sharing options...
PsyCLown Posted March 4 Author Share Posted March 4 So I do have take load together enabled (PV & AC). Yes, I cannot tell the direction of the flow - so cannot confirm whether it is feeding back or not, however the issue is with some meters if you feed back you get charged as if it were usage. If this were the case I expect to be able to see a difference when I adjusted the CT offset - as mentioned it was on 20W by default. I changed it to 199W and then to -199W (basically the 2 extreme ends) and did not notice much difference in the reading so I set it back to 20W as per the default. Yes, power factor needs to be considered but there should not be any load. Getting a reading of over 3A seems quite high and unlikely? I could try again this coming weekend and reduce my loads, these are my normal loads and they are generally high - my geyser was on which added to the load and brought me over the PV limit. I could check again with the geyser off and can turn off some devices to bring the load down. I am on postpaid with a smart meter but never received my CUI, I must still go to Eskom to get it - although not sure how much info is visible from the CUI. Quote Link to comment Share on other sites More sharing options...
Bobster. Posted March 4 Share Posted March 4 37 minutes ago, PsyCLown said: I am on postpaid with a smart meter but never received my CUI, I must still go to Eskom to get it - although not sure how much info is visible from the CUI. Do they give you the CIU if you're not on prepaid? City of Johannesburg do not (though it would cost them nothing to do so). I am watching these smart meters people in the UK are getting (they have to apply and pay, but I doubt it's full price). They get a real time break down of how much they are using, how much that is costing, bill for the month and so on. So quite useful information. It seems to me that what's really happening is that they're trying to make you aware of how much you're using, which gets you thinking to how you can save. I have seen the same happen in COJ with the not so smart meters we get. Even that, having to watch your consumption and make sure you have enough credit instead of just letting the bill arrive and be whatever it is, has the effect of making you more aware of your useage. So really they should let us all have the CIU. "My goodness, Clara! Have you seen how much energy that toaster is using!" I think that a lot of people could make a decent saving on their bill if they knew where it was all going, which would reduce the load on Eskom. OK... conversation around the dinner table could get a bit strained. Quote Link to comment Share on other sites More sharing options...
eugenedp Posted March 4 Share Posted March 4 21 hours ago, eugenedp said: That is concerning. I assume that the interface shows no current draw from the supply? I have not checked mine, I know it draws momentarily from the Eskom side when a large inductive load starts - my battery can only supply 2.4kw. But I have not seen a continuous draw, because I never suspected one or checked for one. I have checked mine, zero draw from Eskom. I have PV&AC jointly enabled, because I run off Eskom between sunset and 22:00. Quote Link to comment Share on other sites More sharing options...
Buyeye Posted March 4 Share Posted March 4 20 minutes ago, eugenedp said: I have checked mine, zero draw from Eskom. I have PV&AC jointly enabled, because I run off Eskom between sunset and 22:00. Mine is the same, I have a pre-paid meter which shows one bar most of the time but no actual usage. Quote Link to comment Share on other sites More sharing options...
P1000 Posted March 4 Share Posted March 4 The inverter may only generate unity power factor when grid-tied. So all the reactive load will be offloaded to the grid. This means that if you only measure current with something like a clamp and your load is not purely resistive, you will always measure something. This is true even when the real power is controlled to 0W. In short - you will measure current even though your eskom-supplied metering device only measures real power of 0W. A clamp is not sufficient. Scorp007 and PsyCLown 2 Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted March 4 Share Posted March 4 Sometimes it's handy to be able to measure reverse flow IF one knows the direction. Here is an example where my grid tied inverter is measuring the power exported to non essential from the inverter via a Sonoff. Normally I use it to measure the power used by an appliance. eugenedp 1 Quote Link to comment Share on other sites More sharing options...
THULANE Posted March 9 Share Posted March 9 Disable PV&AC Take Load jointly. All charge times and AC first set to 00:00. Then it will move from house consumption to backup power (EPS). Scorp007 1 Quote Link to comment Share on other sites More sharing options...
TaliaB Posted March 9 Share Posted March 9 On 2024/03/03 at 11:52 AM, PsyCLown said: Hey all! So something has been bugging me about these Luxpower inverters for a while now, today I finally decided to investigate a bit further and this seems to have confirmed my suspicions and its quite frustrating... I have a voltage protection device connected before my inverter circuit breakers (where Eskom gives power to the inverters). The voltage protection device allows me to see the voltage & current in realtime. I noticed a couple months ago that even when the load for the house is being carried by PV or if I am running on PV & Batteries, there is always current draw being displayed on the voltage protection and this current draw figure varies from time to time and is anywhere from 2.8A to 3.8A when there should be no draw from Eskom. So I decided to stop being lazy and investigate further. I removed the cover of my DB board and used my clamp meter to assist me. Now I do not expect either the voltage protection device or my clamp meter to be 100% accurate but I do expect them to give me a fairly accurate reading. I understand the clamp meter is probably less accurate in this instance. So before I started this test, I ensured that my inverter settings were as such to force the inverter to use PV & Battery only, no grid usage as per the below screenshot. So below you can see a comparison of the clamp meter & voltage protection device both detecting current. One reads 3,9A and the other 4,5A - this confirms to me that there is definitely current flowing So I gave the Luxpower inverters the benefit of the doubt, maybe the voltage protection device is somehow consuming the power... although it seems a bit odd, lets try confirm this. So I turned off the breakers giving Eskom power to both my inverters and suddenly there was no usage displayed on both the voltage protection device & my clamp meter as can be seen below. Now this does concern me and puzzles me a bit, I can understand that the Luxpower does not have an external CT coil and you have the CT coil offset to assist with calibrating it. By default mine was on 20W, I adjusted this (after I turned on the breakers, so my inverter had grid) to 199W and then to -199W and I did not see much (if any) difference to the readings on the voltage protection device or the clamp meter. If we call it an average of 3,2A, since this is basically 24/7 that usage adds up quickly. 3,2A x 230v = 736W 736W x 24 hours = 17,66kWh per day 17,66kWh x 30 days = 529,8kWh in a 30 day month... Its a significant amount. To be fair, this would not all be offset by solar anyways, there might only be around 7 hours in a day where this usage is offset by solar. 3,2A x 230v = 736W 736W x 17 hours = 12,51kWh per day 12,51kWh x 30 days = 375,3kWh in a 30 day month... A potential loss of 154,5kWh per month because of this. At around R4 per kWh on the higher tier, this works out to around R618 per month. So now, does anyone know why the Luxpower does this? Why does it draw soo much from the grid when the loads should be covered by PV or PV & Battery and it should not be drawing from the grid? Also does anyone know whether the same is applicable to the Sunsynk/Deye inverters & Solis inverters? The problem with most AC clamp meters is that it measures Apparant power not True power. The formula for apparent power is P= VxI. True power: P = Voltage x Current x Power Factor. As can see in the formula you need voltage x current x power factor. The clamp meter assume the voltage is 230v and assume the power factor is 1. Unfortunately, the power factor is not constant. It varies from device to device, and how active that device is. What you need is a meter which plugs into a mains socket, so it can sense the voltage and phase, and has a clamp connection, also known as a CT. My brother in law stays in London UK and bought me a nice power meter Dola Tek power meter with CT that plugs into a 230v socket outlet. They are now available on Online Store. I have measured quite a few households that power factors varies between 0.4~0.25. On 2024/03/03 at 11:52 AM, PsyCLown said: If we call it an average of 3,2A, since this is basically 24/7 that usage adds up quickly. 3,2A x 230v = 736W Let us do your current of 3.2A and assume your voltage is 230v and power factor of 0.4. P= 230 x 3.2 x 0.4 = 294W. Link for the Dola Tek power meter. https://reliablestore.co.za/products/pzem-022-open-and-close-ct-100a-ac-digital-display-power-monitor-meter-voltmeter-ammeter-frequency-current-voltage-factor-meter-with-split-ct?variant=36606096769185&sfdr_ptcid=28846_617_662111363&sfdr_hash=b353f4d63665d4823cd3ba1d8f8afc9f&gad_source=1 PsyCLown, Scorp007 and Derek3 2 1 Quote Link to comment Share on other sites More sharing options...
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