Bye Bye Sunny Boy??!

[pipto73]

My old Sunny boy 3000 is 13 years old and is now occasionally tripping out and in - loosing me some valuable output . I would like a replacement that doesn't have any bells or whistles on it - my SB has only the 2 wires from the solar panels (3kw) and a plug with the mains supply making it easy for me to replace in minutes if I could find a modern one that is that simple. Perhaps the modern ones with all their extras don't need wiring in - perhaps they would just fire the Kw's down the grid if left not connected.? - if anyone has any suggestions they would be gratefully received. Plus, of course, I don't want to spend a fortune.

 

[SamDeleted]

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[SamDeleted]

If you fancy fitting your own , Second hand sunny boys are cheap and readily available

 

[pipto73]

If you fancy fitting your own , Second hand sunny boys are cheap and readily available

Thanks for reply Sam - I can easily fit any other inverter that only needs the panel supply wires and an AC supply. I don't really want to get a fairly old though. If the used SB's run like this - then I'm all for it. It's in a steel outbuilding so the internet doesn't work and it's on a complicated spur from the main supply - so CT monitoring is a PITA. - Regards - Phil

 

[SamDeleted]

Thanks for reply Sam - I can easily fit any other inverter that only needs the panel supply wires and an AC supply. I don't really want to get a fairly old though. If the used SB's run like this - then I'm all for it. It's in a steel outbuilding so the internet doesn't work and it's on a complicated spur from the main supply - so CT monitoring is a PITA. - Regards - Phil

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Find many great new & used options and get the best deals for SMA Sunny Boy SB3600 TL-20 3.6KW Solar PV Inverter Like SB4000TL Dual MPPT at the best online prices at eBay! Free delivery for many products.

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Hi Phil


This one should be a straight swap

But points to note: check how your panels are wired , work out how many in series and get your maximum temperature adjusted voltage , make sure the new inverter can handle it


(Or just match the specs old to new ! )

 

[SamDeleted]

What you're after is a straight up old fashioned grid tie, no CT clamp, no WiFi, no frills

You can still find them brand new ,.. but sma sunny boys are notoriously reliable (I know yours just broke lol!) ... Generally second hand models have got years and years of service left in them

 

[pipto73]

Many Thanks for your replies Sam - I've got that one on my list of probables - according to the specs it exceeds all the parameters of my old one except it says 550volts max - mine is 600. I have never seen my voltage go over 440 - but I've never really looked hard! I don't know how to measure my "maximum temperature adjusted voltage" I'm quite handy at normal electrics ,but, with the old SB being so reliable I've never had reason to look into any of this. The panels are/were rated at 3.15Kw - but that was 13 years ago and they rarely put out over 2800 now. There are 14 of them on a single pair of wires.

 

[SamDeleted]

There are 14 of them on a single pair of wires.

Is it possible to get a photo of the label on the back ?


I'd be very surprised if the voltage got over 550v

 

[pipto73]

Do you mean this label? - I have just spoken to the vendor - seems knowledgeable and helpful - i needed to confirm that the panel wire clips/adaptors were the same - he can't see any problem with its compatibility - but he is the "seller".

 

[SamDeleted]

Many Thanks for your replies Sam - I've got that one on my list of probables - according to the specs it exceeds all the parameters of my old one except it says 550volts max - mine is 600. I have never seen my voltage go over 440 - but I've never really looked hard! I don't know how to measure my "maximum temperature adjusted voltage" I'm quite handy at normal electrics ,but, with the old SB being so reliable I've never had reason to look into any of this. The panels are/were rated at 3.15Kw - but that was 13 years ago and they rarely put out over 2800 now. There are 14 of them on a single pair of wires.

440v / 14 panels = 31.4v per panel (assuming they are in series)

At most they'll give out 36v ,

36 x 14 = 500v~


You want to leave a bit of clear blue water above

 

[pipto73]

I've bought it now - once again -thanks for all your help - regards - Phil

 

[RCinFLA]

My guess is the high voltage electrolytic capacitors are getting old, with electrolyte dried out dropping their capacitance.

GT PV inverters put a lot of ripple current through their HV DC filter capacitors. High ripple current and electrolytic capacitors' ESR internal resistance means constant heating of capacitors accelerating the dry out of their electrolytic paste.

Sometimes the tops of the electrolytic capacitors are puffed outward indicating internal pressure build up from heat.

 

[Hedges]

I've bought it now - once again -thanks for all your help - regards - Phil

SMA Sunny Boy SB3600 TL-20 3.6KW Solar PV Inverter Like SB4000TL Dual MPPT | eBay

Find many great new & used options and get the best deals for SMA Sunny Boy SB3600 TL-20 3.6KW Solar PV Inverter Like SB4000TL Dual MPPT at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

"SMA Sunny Boy SB3600 TL-20 3.6KW Solar PV Inverter Like SB4000TL Dual MPPT"

https://files.sma.de/downloads/SB3600TL-20-DEN115010.pdf

Your old inverter was transformer type, probably negative ground. That means all PV cells are biased to positive voltage relative to their grounded frames.

The new inverter is transformerless. That means half the PV cells will be biased positive relative to ground, half will be biased negative relative to ground.

There is something called "PID", Potential Induced Degradation. The voltage bias drives ions from epoxy and glass into the cells, causing degradation. In some cases, quite rapid.

Because you have an older system with older panels, it is possible they suffer badly from PID. Or not. Among modern panels, since this issue was identified, some are more resistant than others.

https://files.sma.de/downloads/PID-TI-UEN113410.pdf

https://files.sma.de/downloads/Duennschicht-TI-UEN114630.pdf

Potential-induced degradation - Wikipedia

en.wikipedia.org

 

[pipto73]

Hi "Hedges" - just back from hols and read your "PID" document. - very interesting. I see in the "corrective measures" description it says " Grounding the negative pole of the PV array resolves this problem. " - Does this mean that, by running an earth wire from the negative wire coming from the panels to the inverter (at the DC switch would be handy) to an earthing pole - I do have one already installed as building is made of steel I can avoid the risk of this problem? Many thanks for your input - Ps - all working fine ATM.

 

[Hedges]

Your old inverter grounded the PV- lead, probably through a fuse (if short occurs elsewhere, fuse blows, inverter detects that and shuts off.)
New inverter is transformerless, ungrounded. It can't operate with either PV- or PV+ grounded, and might be damaged.

I think while the inverter is not operating, at night, the PV array could be grounded or even driven to a positive voltage. That was supposed to reverse at least some aspects of PID. But it would take a circuit to accomplish that automatically.

I doubt these are readily available anymore.

SMA PVO-N-20 User Manual

manualmachine.com

SMA PVO-Box PVO-11

Restposten - Bezeichnung: PVO-Box PVO-11

www.solarlager.com

Given the very low current involved, I might be tempted to use a high value resistor, suitably high voltage, to draw PV leads to a positive voltage. Low enough current to not trip protection. But I have background to figure that out, and know the risks including shock.

Your existing panels may suffer badly from PID, or maybe negligible.
I would have preferred a replacement transformer-type inverter.
If the panels do degrade too much, you'll end up replacing them. Good news is panels today are 1/10th to 1/5th the price of 20 years ago, and used panels in good condition are even less. You would have to get panels matching the voltage and current range of the inverter, but it likely supports a wider range than old inverter did.

 

[pipto73]

"I think while the inverter is not operating, at night, the PV array could be grounded " So- I could run a wire to earth through a timeswitch set to, say 10pm-4am?? Yes - I see the SMA item isn't available.

 

[Hedges]

There is the potential for damage if a circuit doesn't do what is needed, and shock hazard if voltage is unexpectedly present when someone works on it.

I might design a circuit for my own use, with resistors to limit current flow and some other design considerations.

What you could do is monitor output, see if it starts to decline. And watch for a transformer type inverter on eBay.