Ampage question that NAPIT cannot answer.

[bobbiecool]

If you can force the installer to deal with it then i think the best solution is different panels in that location with greater string voltage.

If YOU are fixing it, you may consider just buying a standalone MPPT controller which is more compatible with the voltage and amperage from the existing panels, and adding it to your setup. The advantage of that is that all the work which would need to be done to install it would be inside your house (or wherever the Growatt is, but likely indoors and with a level surface to stand on and no ladders or harnesses or buddy system involved). Downside is if you are trying to do a bunch of logging/tracking through the growatt inverter itself, running the 6s string through a separate mppt would take that information 'offline' or to a 2nd system which may be undesirable to you.

Another option may be to add more roughly-south-facing panels to the 6s string, but in another location. Even if you had room for only 2-3 panels on another south-facing surface, there is no reason you couldn't wire them in series with the existing 6.

I do have another south facing roof, However, its lower and prone to shading from a tree.
From the very beginning of this rather sorry affair I've wanted those 6 panels replaced. You'd think that's easy, right? But trying to deal with a company that has very poor communication and believe they are blameless is a nightmare. NAPIT, an accredited scheme operator who investigates poor installations, are really dragging their heals on this. And what's more is they think that by installing TIGO's is an acceptable solution! An absolute farce.

 

[kommando]

You can get hacked SolarEdge panel optimisers with custom voltages and get the volts set higher which will also drop the amps. But why should you when you paid someone for a working install, I would be getting them to replace the panels with ones with higher volts and less amps. A set of south facing panels should be getting the best output per watt of panel not the least.

 

[zanydroid]

You can get hacked SolarEdge panel optimisers with custom voltages and get the volts set higher which will also drop the amps. But why should you when you paid someone for a working install, I would be getting them to replace the panels with ones with higher volts and less amps. A set of south facing panels should be getting the best output per watt of panel not the least.

Do you have a reference or keywords for where I can read up on the voltage / current hacking and behavior on those optimizers? I'm trying to understand how optimizers coordinate the current and voltage balancing.

 

[kommando]

Other than them being for sale despite much research I could not get past that they exist. The one I bought set to 37V, measured 37V when I connected it to a shaded panel and the other 5 unshaded panels were released so the inverter looked at 5.5 panels of output and not only 3.

https://www.aliexpress.com/item/1005004730749964.html?spm=a2g0o.order_list.order_list_main.62.14b61802mNB4FT

 

[zanydroid]

Other than them being for sale despite much research I could not get past that they exist. The one I bought set to 37V, measured 37V when I connected it to a shaded panel and the other 5 unshaded panels were released so the inverter looked at 5.5 panels of output and not only 3.

https://www.aliexpress.com/item/1005004730749964.html?spm=a2g0o.order_list.order_list_main.62.14b61802mNB4FT

Ok thanks, so they are solar edge style (at least in having MPPT) but probably not solar edge.

Didn't it have to reduce the voltage in your case to achieve the current match?

Do you know how long these things have been around? I've been monitoring for UL listed variants to show up in the US.

 

[zanydroid]

Oh wait I see SolarEdge branding on these. There's some supported ways to reprogram SE into compatibility mode with third party inverters, maybe all they are doing is buying a bunch of used or seconds and doing that.

 

[kommando]

Yes, the one I got looks 100% SolarEdge and in good condition but signs of use, without the hack they output 1V when connected to any inverter other than a SolarEdge.

 

[zanydroid]

Yes, the one I got looks 100% SolarEdge and in good condition but signs of use, without the hack they output 1V when connected to any inverter other than a SolarEdge.

Unlocking 1V can be done with SolarEdge key.

Powering People’s Lives Around the World | SolarEdge

Turn your businesses and homes into a sustainable energy hub with a SolarEdge inverter solution and the SolarEdge energy manager platform.

www.solaredge.com

The 1v standby behavior until they get wakeup signal is a North America code compliance thing.

The fixed output voltage (which might mean fixed buck ratio), I'm not sure.

I think 6 of these would be needed for OP if it comes to it，but tbh if the system needs to be modified it's probably best to stick with minimum hacks involving exotic hardware. For maintainability over the next 30 years

 

[kommando]

If I had DIY installed and then realised it was my error the panels were not performing I would use the SE optimisers but this is a professional install with a premium price over DIY so it should work as advertised. Retrospectively applying a fudge which will have its own inefficiencies as no electronics is 100% efficient so I would not accept this as a solution.

Thanks for identifying the tool, at £100 I will buy them already hacked .

 

[zanydroid]

https://knowledge-center.solaredge.com/sites/kc/files/se_application_fixed_string_voltage.pdf

This explains the various control loops in SE and what the MPPT ends up doing.

These AliExpress folks probably figured out the PLC protocol and sent the output voltage command to the module.

 

[bobbiecool]

If I had DIY installed and then realised it was my error the panels were not performing I would use the SE optimisers but this is a professional install with a premium price over DIY so it should work as advertised. Retrospectively applying a fudge which will have its own inefficiencies as no electronics is 100% efficient so I would not accept this as a solution.

Thanks for identifying the tool, at £100 I will buy them already hacked .

Thanks for your reply. I agree, although NAPIT sees it as an acceptable solution if they work, which I find baffling as I see this as the installer putting a plaster over their mistake and hoping it will work, given the fact that TIGO's arent designed for this application.
As it stands the installer are suspended, which means they cannot sign off any work until they get back with a new design showing how the TIGO's will work with my system. I will not accept anything less, efficiency wise, than what was expected when I bought the system.
All of this frustration because they refuse to replace 6(!) panels.

 

[bobbiecool]

If anyone is interested I have just had all 18 panels replaced by the installer. It has just transpired that not only did I have a voltage issue my annual production total was down by 1/3 to what I was originally quoted, just over 2100kw shy. Apparently the panel manufacturer, Eurener, have admitted to my installer that the 410 MEPV80 half cut have not been performing as advertised, hence my annual shortfall. It doesn’t excuse the fact that the 2nd string voltage was way too low, however the outcome is acceptable. Hopefully I can now draw a line under it.

 

[zanydroid]

Geez, what a layer of shit. Glad it worked out. Fingers crossed.