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ThatsNotMe

Question about display panel on SB 2000 HF

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ThatsNotMe

Hi

 

Could someone confirm whether, if the DC power from the panels isn't enough to start up the inverter e.g. around 100 to 150v, that the graphical display panel on the Sunny Boy would still show the voltage, but with the "gate" open indicating that the inverter wasn't doing any converting?

 

Reason I'm asking is because I'm not getting any power from my panels, but an electrician has confirmed that the panels are registering DC of about 185v (on a rainy and dark afternoon).  The inverter is also not showing any DC or amps on the panels side of the graphic display.  I'm not getting any error msgs from the SB and have tried rebooting the system a few times.

 

Many thanks

 

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Sharpend

I’ll tap up our resident solar specialist. 

@binky

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binky

you may have a voltage, but that doesn't necessarily mean enough power to actually work. Sunny Boys (older versions) tend to kick-in at around 150W, newer versions work from around 70W (from memory). How long has the system being playing up? It sounds like this is more than a 1 day issue - incidentally, most electricians don't know what they are looking at unless they have been involved with solar work. Given the time of year, I would expect some output from the system, even if it is raining, between 11am and 3 pm.

 

Couple of questions:-

1/ what panels do you have and how many?

2/ how old is the inverter?

3/ is the inverter showing any warning codes or a red LED?

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ThatsNotMe

Thanks Binky

 

The electrician confirmed over the phone to SMA that he had a reading of 186v from the panels.  Unfortunately he didn't ask them whether they'd expect that voltage to be displayed on the SB even if it wasn't converting.  The image here SB2000HF image shows where I think the voltage and amps should display.

 

The answers to your questions are:

  • There are 8 moser baer 235w panels which are 7 years old
  • The inverter is 6 years old
  • No warning codes and no red LED.  The only light that comes on is the bluetooth when the sunnybeam connects.

The electrician who came round is from a company that fit solar panels, although they are mainly traditional electricians.  Their next suggestion (prompted by SMA) is to get a cherry picker up to the roof and check the panels, but as there was voltage detected from the panels I'd like to definitely rule out an inverter fault before they get up on the roof.

 

Many thanks for any other advice you can give.

 

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Andy™

i dont do solar, but id be checking the short circuit amps on the panels along with voltage. you might have the voltage with open terminals, but once conencted and no amps, its not going to do anything

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binky

Ok HF inverter is pretty old school, and will require a higher wattage to start up, but that picture shows the bar graph of output. On the day that was taken you have clearly been generating. From data sheet it would seem you have a single string inverter, so it should be showing panel voltages on the display along with grid voltage on RHS. The fact that it isn't may just be a software glitch or display fault.

 

There is absolutely no need to access the roof to check panel outputs, or check for earth leakage - try a different company. As Andy has pointed out, it is possible to check the Voc and Isc values with simple test gear. Clearly checking on a sunny day will make any results more obvious. The only thing that would require roof access is finding an earth leakage fault, after confirming at the inverter that one exists. However, as no fault codes are being shown, it would suggest the inverter and system is working fine. There is one exception to that, I have had Sunny Boys fail to convert DC to AC power, but display no faults. This will be obvious, if the sun is out and there is little useable power being generated, you can also keep an eye on the generation meter, if it isn't changing the system isn't outputting

Edited by binky

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ThatsNotMe

Thanks Binky

 

Actually, that graph on the display cycles between current day and previous days.  There hasn't been any generation since last Sunday.

 

That's good to know that they shouldn't have to access the roof, but doesn't that figure of 186v that the electrician registered from the panels (when it was raining and quite dark) suggest that I might have another SB that is showing the same symptons of failing to convert that you've seen before?  Did you have to replace the inverter in those cases?

 

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binky

It does sound like a failed inverter. Being 7 years old it will be out of warranty, unless you bought an extended warranty of 10 years or more. If it is out of warranty, as much as I like SMA, I think I would replace with a Chinese unit such as Solis - half the price! 

 

Now SMA always ask the same questions, so basically you need to tell them the panels are good, the AC connection is good, and therefore it has to be the inverter. Their response times are normally very good (part of the reason I use them), so if it is replaceable under warranty, you should be up and running in a week.

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ThatsNotMe

Thanks for your advice binky, I'll let you know how I get on!

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ThatsNotMe

Hi @binky

 

I rang the electrical company that came out, to query their assumptions on the next steps and spoke to another electrician. 

 

I queried that they were seeing 186v but nothing on the inverter and he said that they'd expect to see 300v on an open string (I think that's what he said), 37v x 8 panels, so that's why he thinks they should check the panels. 

 

However, he did seem to have doubts about why I wasn't seeing any volts on the graphic display and he said that they could send someone round on Thursday to check again when it's sunny.

 

Is what he's said plausible?

 

Thanks

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binky

Depends how he checked the panels. If he disconnected the +ve and -Ve at a sunny part of the day, they maybe correct. If it was checked at late afternoon ie getting dark, you would not always see a full voltage even in open condition. If he checked the voltage with the strings still connected and inverter turned on, you wouldn't get the OC voltage becuase the inverter would be trying to convert the eenrgy which drops the voltage and raises the ampage to get power. But the fact the inverter is showing nothing, not even the grid voltage would suggest that the fault lies there. If there was a break in the DC you wouldn't get a voltage at all except in reference to earth, and if there is an earth leak, you get a steady volatge in refrence to earth as the fault allows current flow. It's a bit hard to comment without knowing exactly what they did. The other possibility is failed by-diodes in 3 panels, but that wouldn't stop the inverter working. I have to say fault finding solar is still a relatively new skill, and it isn't always very obvious how to proceed, or what certain things mean. Having had very few faults with systems I've installed, I'm still learning myself, but obvious issues are obvious issues and no display...

 

HOw easy is it to access the panels? If it's  aquick shim up a ladder to a flat roof it's easy enough to check the connectors yourself. Another daft question, have you turned AC and DC isolators off and re-booted the inverter? Is there a non-flashing red led on the generation meter indicating the cct is live? Inverters are a bit like computers, sometimes they just need a kick up the arse! Turn off, leave for about 5 mins to discharge the capacitors, then turn on. YOu should then see the boot up sequence on the display. See below. 2nd video is later model but in English

 

 

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ThatsNotMe

The electrician came back today as it was sunny to run another test of the voltage from the panels and he registered 289v.  This was by taking the cover off the DC switch and connecting the meter to the terminals.  He was happy that this was plenty of v and SMA have now confirmed that it must be the inverter that is faulty!

 

The electrician is suggesting replacing with a solaredge inverter and optimisers on the panels (I do get some shading on one panel in the afternoon from the chimney.

 

Any thoughts on that?

 

Thanks

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roys

What about eBay, plenty SMA inverters on there, new and 2nd hand.

Just had a look and there is a refurbished one for £150 delivered for a SB2500 item number 222825871174.

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binky

SMA have a feature called Global Opti-tracking that compensates for shade. See below. Panels also have by-pass diodes, if a panel is not peforming it gets by-passed so shading is not the big issue people make it out to be.

 

https://www.sma.de/en/partners/knowledgebase/optitrac-global-peak.html

 

So:-

1/ you will not get 25% extra performance - 

2/ no doubt cost is about £2.5 - 4K. Even if you did get a bit extra output how long will it take to pay for itself.

3/ SMAs are expensive and yours is probably out of warranty. You could opt for a Solis at about half the price with a 10 year warranty as standard. I'm not a fan of Chinese products, but these seem OK and performance is nearly as good as a SMA, or as Roy says above get a refurbished SMA, at £150 that''s a bit of a bargain and worth a punt! 

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ThatsNotMe

I've had the SMA swapped out for a new Solis and all seems to be working well.  Thanks for your advice @binky

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binky

:Welcome:  I'll be interested to know if you spot any notable performane differences. It's a bit difficult to direct compare outputs because the weather is never the same year to year.

Edited by binky

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roys

Well mines have produced nowt in the last week due to a healthy covering of snow.

 

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