Can anyone help please. I have a 3kw must inverter with 2x hubble 100ah batteries. This has been working fine as a backup system for the last 3 weeks.  On the weekend I installed 6x460w panels. 3x panels in series and the 2 strings connected in parallel and then to the inverter. At the inverter I measured 135vdc. The amps is about 22A. 

The is no pv connection or icon showing on the inverter screen. 

Max Voc is 145vdc

Must PV18-3024 VPM

1 hour ago, Rolfedw said:

Can anyone help please. I have a 3kw must inverter with 2x hubble 100ah batteries. This has been working fine as a backup system for the last 3 weeks.  On the weekend I installed 6x460w panels. 3x panels in series and the 2 strings connected in parallel and then to the inverter. At the inverter I measured 135vdc. The amps is about 22A. 

The is no pv connection or icon showing on the inverter screen. 

Max Voc is 145vdc

Must PV18-3024 VPM

Is the 22A the current from the panels to the MPPT? 

3 series is OK now but on cold day you might get to close to the all time maximum of 145V

Edited April 17, 20233 yr by Scorp007

Perhaps something in the settings where solar charge has to be enabled? Any error codes?
Do you have a DC breaker before the connection to your MPPT?
Did you do the MPPT connection whilst the Inverter was shut down and zero PV (i.e. DC breaker off) before restarting the Inverter and then switching on the DC breaker?
 

You are very close to its top volt limit and if I have the rite specs it's operating volts is 30 to 120v max 145v it could be the inverter is not happy with the 3 in series and not activating the mppt,  if all else fails try 2 panels in series and see if it works as I have read before that  some mppt controller don't like volts to close to its limits .

Check if  the setting are still set on charging source  to utility only and change the setting for solar 

Edited April 17, 20233 yr by GMAC

Thank you for the  replies. I have tried the different settings over and over. IE: SBU and SOL but still no pv showing. I put it back to UTI so at least the grid charges the batteries. 

I am going to try cancelling 2 panels so 2 are in series and connected in parallel with the other 2 also in series. 

2 hours ago, Rolfedw said:

I am going to try cancelling 2 panels so 2 are in series and connected in parallel with the other 2 also in series. 

I would suggest try two panels in Series as GMAC said, if that works, then you can still do the 2 in series but with 3 parallel strings, i.e. a 2S3P config.

Hi guys. I tried cancelling 2 panels. 1 from each series string. Got 88vdc at the inverter but no recognition of solar input on the inverter screen. 

Do you think inverter problem?

Exasperated Rolfedw 

8 minutes ago, Rolfedw said:

Do you think inverter problem?

Certainly sounds like it. Would suggest you have it checked; and hold onto those panels, you may just kick yourself if it happens to be an MPPT issue.

 

Yes. Usual story. Buy cheap get shi......

Sorry that we could not fix your problem but cheap is not always bad as I have a cheap system now for 4 years+ and still going strong so have the inverter checked out .. 

4 hours ago, Rolfedw said:

Yes. Usual story. Buy cheap get shi......

DOA happens to the best of them. Yours was not DOA at least. There are enough happy MUST users. 

1 hour ago, GMAC said:

Sorry that we could not fix your problem but cheap is not always bad as I have a cheap system now for 4 years+ 

Add me to the list of a cheap system. Equipment cost:

Inverter R5000

Panels R10000

Power generated 7319kWh in 4 years. Top of picture. 

Never had to set or adjust anything and just sits silently on the wall. 

In my case time is my friend just like when you make investments. 

Edited April 18, 20233 yr by Scorp007

Sorry Sorry Sorry guys. Problem solved. It was an IDIOT problem. Yesterday afternoon after phoning the supplier I suddenly realised I connected red wire to the y connector thats connected to female of the panel that goes to the inverter and black to the male side. 

For a quick fix I swapped the wires at the bottom of the isolator. 

Everything working 100%.

I will never make that mistake again. 

Thanks again everyone for all your help. 

1 hour ago, Rolfedw said:

Everything working 100%.

Glad you got it sorted. And you can be thankful your "cheap" hardware seemingly has reverse polarity protection. 

😀very thankful indeed 

👏👏 . 

Very lucky .

Glad it's working 

On 2023/04/19 at 3:59 PM, zsde said:

And you can be thankful your "cheap" hardware seemingly has reverse polarity protection. 

Actually, I think any solar charge controller should be automatically reverse polarity protected (without designing anything specifically for that purpose), because of the inherent (sometimes explicit) free-wheel diode in every MOSFET, and the inherent current limiting nature of solar panels. The panels and MOSFET would just have seen Isc current, which is only a few percent higher than Imp current.

I'm not totally clear about whether MOSFET free-wheel diodes are rated for full rated forward current in the reverse direction, but I'd say that most would survive it at least for a short time.

In short, I don't see this as proof of a great design with good safety margins and features. Just the nature of boost (and buck) converters.