Hello everyone,

We moved to a house over a year ago and had some frequent electricity outages (not major ones, but just for a few hours). We decided to get some batteries and figured we may as well put up a few solar panels while we're at it. We contacted a company that took care of it for us. We now have 4 batteries with a total capacity of 5KW, 4 solar panels (not much I know) and a Must Solar Inverter: PV18-5048 VHM.

Now we had some problems with the power and since the company that installed it was not helpful another company helped us out with that. Power wise things are working well now. Panels are working, battery is working when the power goes out. The only problem is that the inverter let's out a loud BEEP like 30 times a day. I have the feeling that it has something to do with there being sun on the panels or not, but that's just a guess. I have looked in the manual and turned off the two settings that are related to an alarm, but that doesn't do anything. I see in the manual there's an icon that should be on the display when all alarms are off, but it isn't showing. Of course there's nothing in the manual about how to achieve this. I have sent questions to Must Solar (Chinese company) a few times, but they simply don't respond to anything.

Apologies if this forum is not the right place for a question like this, but I'm pretty desperate here 😩 Thanks in advance for any response.

1 minute ago, Cheburashka said:

Hello everyone,

We moved to a house over a year ago and had some frequent electricity outages (not major ones, but just for a few hours). We decided to get some batteries and figured we may as well put up a few solar panels while we're at it. We contacted a company that took care of it for us. We now have 4 batteries with a total capacity of 5KW, 4 solar panels (not much I know) and a Must Solar Inverter: PV18-5048 VHM.

Now we had some problems with the power and since the company that installed it was not helpful another company helped us out with that. Power wise things are working well now. Panels are working, battery is working when the power goes out. The only problem is that the inverter let's out a loud BEEP like 30 times a day. I have the feeling that it has something to do with there being sun on the panels or not, but that's just a guess. I have looked in the manual and turned off the two settings that are related to an alarm, but that doesn't do anything. I see in the manual there's an icon that should be on the display when all alarms are off, but it isn't showing. Of course there's nothing in the manual about how to achieve this. I have sent questions to Must Solar (Chinese company) a few times, but they simply don't respond to anything.

Apologies if this forum is not the right place for a question like this, but I'm pretty desperate here 😩 Thanks in advance for any response.

Post a picture of you display. I presume you switched of some notifications. Do you know under what condition the beep might be present?

30 seems like a regular alert.

1 hour ago, Scorp007 said:

Post a picture of you display. I presume you switched of some notifications. Do you know under what condition the beep might be present?

30 seems like a regular alert.

Here's a picture of my display. Not too much to see here I guess? In the manual it shows there should be a speaker icon on the display if alarms are muted, but I don't see it. In the manual I can find two settings related to alarm and I set them both to off. No other information in the manual about how to mute these alarms.

I think the alarms are given when perhaps there's no power generated by the panels or when power is being generated again. This based on the fact that beeps always seem to happen around sunup / sundown, but they do happen during the day as well. Since our house was constructed without these panels / inverter in mind unfortunately the inverter is places in a spot where the beeps are a real annoyance.

2 hours ago, Cheburashka said:

Here's a picture of my display. Not too much to see here I guess? In the manual it shows there should be a speaker icon on the display if alarms are muted, but I don't see it. In the manual I can find two settings related to alarm and I set them both to off. No other information in the manual about how to mute these alarms.

I think the alarms are given when perhaps there's no power generated by the panels or when power is being generated again. This based on the fact that beeps always seem to happen around sunup / sundown, but they do happen during the day as well. Since our house was constructed without these panels / inverter in mind unfortunately the inverter is places in a spot where the beeps are a real annoyance.

The speaker icon could be in the display but not used. Yes 24 and 25 should switch the beeps off if working correctly. You might have a notify beep when the PV kicks in and out.

The beep could also be as above if you have your earlier setting to use solar 1st. Then it will alert when PV does not provide power at sunset and informing it's back on in the morning.

Do you use the inverter to keep power on at all times or only during interruptions?

I am sure those that know the PCB will be able to say where you can permanently disconnect it.

Edited August 17, 20223 yr by Scorp007

1 hour ago, Scorp007 said:

The speaker icon could be in the display but not used. Yes 24 and 25 should switch the beeps off if working correctly. You might have a notify beep when the PV kicks in and out.

The beep could also be as above if you have your earlier setting to use solar 1st. Then it will alert when PV does not provide power at sunset and informing it's back on in the morning.

Do you use the inverter to keep power on at all times or only during interruptions?

I am sure those that know the PCB will be able to say where you can permanently disconnect it.

With the solar first setting you mean setting number one? It's currently set to SUB which means solar first, utility second and then battery. So perhaps every time solar is not up to the task it will give this beep? The sad thing is that all the settings for 1 either have solar as first or it's just utility and only solar / battery if utility is out. That would mean all the solar energy would be wasted because we don't give anything back to the grid. Now with 4 panels that's not the end of the world, but it would be suboptimal if the only solution to these beeps is to always run on utility except for an outage.

And yes the inverter is always running. That's the only way to seamlessly switch in case of a utility outage, right? (I'm not that technical to be honest, at least not when it comes to electricity).

4 minutes ago, Cheburashka said:

With the solar first setting you mean setting number one? It's currently set to SUB which means solar first, utility second and then battery. So perhaps every time solar is not up to the task it will give this beep? The sad thing is that all the settings for 1 either have solar as first or it's just utility and only solar / battery if utility is out. That would mean all the solar energy would be wasted because we don't give anything back to the grid. Now with 4 panels that's not the end of the world, but it would be suboptimal if the only solution to these beeps is to always run on utility except for an outage.

And yes the inverter is always running. That's the only way to seamlessly switch in case of a utility outage, right? (I'm not that technical to be honest, at least not when it comes to electricity).

The solar 1st would use all the solar available and not waste it. Only when not enough would it draw from battery or utility.

I don't know the Must settings but most are similar to the Axpert.

You just need to alter some settings and see if it does not help. Change a setting at a time and see.

3 hours ago, Cheburashka said:

So perhaps every time solar is not up to the task it will give this beep?

Yes it will. It will sometimes do this a few times in the evening at sunset when running in SUB as solar is the primary source and it kicks off and on. It might also do this on cloudy days if there is not enough sun when clouds pass by, does it beep during the day on cloudless days?

It sounds like the setting is not being saved when you are turning off the alarm because the icon is not showing up on screen, just be sure to press enter after changing the value and then wait a bit for the system to return to the main screen for it to be saved. Then go back to setting 24 & 25 and check if they are indeed changed and saved.

On 2022/08/17 at 11:50 PM, jumper said:

Yes it will. It will sometimes do this a few times in the evening at sunset when running in SUB as solar is the primary source and it kicks off and on. It might also do this on cloudy days if there is not enough sun when clouds pass by, does it beep during the day on cloudless days?

It sounds like the setting is not being saved when you are turning off the alarm because the icon is not showing up on screen, just be sure to press enter after changing the value and then wait a bit for the system to return to the main screen for it to be saved. Then go back to setting 24 & 25 and check if they are indeed changed and saved.

Been a few busy days, but spent some time tinkering around and unfortunately without much luck. I tried a few things:

1. Set the first setting to Utility first, this didn't help. Beeps during the whole day including in the evening when it's pitch dark outside.

2. Had another go at the alarm settings, nothing changed.

3. Changed setting 1 back to SUB and also beeps during the evening when pitch dark outside and solar doesn't even show up in the display.

4. Changed the setting for background light to be always ON, this works. Confirming that saving settings should work, although this doesn't prove that changing all settings work.

I guess the beeps are not related to load since it happened on both SUB and UTL and even in the evening when pitch dark outside. Load is never near 100%, no error codes are shown when the beeps go off. Not sure what else to try.

15 hours ago, Cheburashka said:

I guess the beeps are not related to load since it happened on both SUB and UTL and even in the evening when pitch dark outside. Load is never near 100%, no error codes are shown when the beeps go off. Not sure what else to try.

This is very strange, I'm also not sure what to try. I don't have a Must, so it is difficult to diagnose without any error messages displayed, which in itself is strange. My next guess would be that the load is too high, but as you say it isn't, so I have no clue otherwise, sorry.

Beeping at night on my old 5k axpert clone was most likely due to a high panel voltage on a cold night on a low voltage model, but at least I got some error messages when it happened.

1 minute ago, jumper said:

 

Beeping at night on my old 5k axpert clone was most likely due to a high panel voltage on a cold night on a low voltage model, but at least I got some error messages when it happened.

I find it strange that you could get a high voltage at night even on a cold night. I normally have less than 4V during the night.

1 hour ago, Scorp007 said:

I find it strange that you could get a high voltage at night even on a cold night. I normally have less than 4V during the night.

During the night the SCC will read 0V, it's only at dusk and dawn that it kicks on and off. It was happening about 1hr after sunset, I figured with a Voc of 136.6V@25C and it easily getting to -5C I was overshooting the max voltage when the SCC was disconnecting and reconnecting as it does as the PV gets low. It started happening in the mornings too, about 1hr after the sun hit the panels, but I think that was because of components already failing due to the error messages I was receiving... unfortunately there is no error message for too high PV input voltage, you only get one when other things fail.

@jumper

Yes I can understand one hour after sunrise but not after sunset. Too little irradiance for panels to give a higher output voltage due to the temp constant for Voc.

Just how I understand it.

@Scorp007 @jumper I think the mystery has been solved. I am using an external device (see photo) that sends the data to a website where I can see power generated. It's pretty basic, but it's something at least. I have it on my WiFi guest network and recently switched from VPN on my devices to VPN on the router. I think this blocked the guest network access for some reason and the inverter was probably beeping because the device couldn't transmit data. Since I added an exception that told my router not to use VPN for this device the beeping has stopped.

I realize now I should have added this information, but forgot. Now I'm not a 100% sure of course but so far so good.

Wanted to thank you both for the help and let you know the (possible) problem/solution.

Edited August 23, 20223 yr by Cheburashka

44 minutes ago, Cheburashka said:

@Scorp007 @jumper I think the mystery has been solved. I am using an external device (see photo) that sends the data to a website where I can see power generated. It's pretty basic, but it's something at least. I have it on my WiFi guest network and recently switched from VPN on my devices to VPN on the router. I think this blocked the guest network access for some reason and the inverter was probably beeping because the device couldn't transmit data. Since I added an exception that told my router not to use VPN for this device the beeping has stopped.

I realize now I should have added this information, but forgot. Now I'm not a 100% sure of course but so far so good.

Wanted to thank you both for the help and let you know the (possible) problem/solution.

Good you got the???? mouth silenced 😀this could be a help for others.

So many times we change a configuration and something works not as intended.

Thanks @Cheburashkathat's good news, I guess they never programmed an error code for that situation, glad it's working silently again. That's an interesting wifi device I've never seen, where did you get it?

11 hours ago, Scorp007 said:

@jumper

Yes I can understand one hour after sunrise but not after sunset. Too little irradiance for panels to give a higher output voltage due to the temp constant for Voc.

Just how I understand it.

I see now from the data on my new king that you are correct, the voltages seem too low in the evening with low light, I never had any real data from the old inverter, I was reading off the screen which I later found out is not accurate at all. The first time it actually switched off with an error message was in the evening, so that led me to believe it was evening voltages, but by then it was probably already damaged because it was telling me the batt voltage was 120V 😱

On 2022/08/23 at 9:44 AM, jumper said:

Thanks @Cheburashkathat's good news, I guess they never programmed an error code for that situation, glad it's working silently again. That's an interesting wifi device I've never seen, where did you get it?

Sorry for the late response, I don't get any email notifications and just now checked up on the post. I bought this on Aliexpress after I found it on the Must Solar website. I tried contacting them to buy it directly, but they have never responded to any of my queries (really poor company). So I just picked it up on Aliexpress and hooked it up. It uses some wonky Chinese site and to be honest the information is really basic. It shows your power generation for the day, week, month, year and that's about it. They also have some wonky software that you can use and connect your PC directly, but that's not great either. I think I paid about 80 USD for it. With all the trouble it has caused with those beeps it wasn't really worth it haha

2 hours ago, Cheburashka said:

Sorry for the late response, I don't get any email notifications and just now checked up on the post.

No worries, thanks for the feedback, much appreciated. Good to know a device like this exists that seems to send RS485 and RS232 over wifi, even if the software is crappy. Maybe with some hacking this could be a way for me to connect to my battery (RS485) and inverter (RS232) independently over wifi, very interesting. I'll take a look into it when I find a chance to tinker with something new. Cheers.