Diehl 3800s inverter and problems with 61009-1 B rcbo's??

[Worcester]

Neither the SMA or the Power-one will cope with a single string the MPP voltages are too high in cold wether conditions. Fire it up as a single string and you will damage the inverter.

As the Diehl 3800TLD only has a single MPP tracker, it needs to be configured as two identical strings ( 2 x 8) to avoid damage to the inverter, although even then the MPP Voltage range is outside the tracking range of the inverter. This is in simple terms a very bad design and a mismatch with the inverter. Whowever designed it / specified it should have checked the parameters first.

As 2 x 8 , it won't blow up, however it will perform well below its capabilities. You should swap the inverter for a Power-one OUTD 3,6 or SMA 3600TL

See attached from PV*SOL output for the Diehl 3800TLD when configured as a single string.

 

[SibertSolar]

I think the 3800tld will be ok on 2 strings of 8 from a voltage/MPP point of view - max Voc will be approx 500vdc even in cold weather and the mpp range is 350-710vdc.... My only minor concern would be the 11.5A max input current. Although ok with the very low Isc on those panels (2x 5.35A) you wouldn't have much of a "safety margin" (ideally 25%) on top. An Eltek 3.8HE-t would be much better suited...and can be capped at 16A on the AC output if required.

 

[Worcester]

The problem with the 2 strings of 8 is the start up voltage when the panels warm up - i.e. the most sunny days when the most kWh should be generated, - IF they get to the top of the scale the Vmpp drops below the tracking voltage of the inverter.

The HJ Panels are good panels - we've used loads and loads of them, their high Voc does mean that you have to design the system properly. For the customers sake, let alone reliability, the Diehl shouldn't rally be used on this installation.

see screenshot of 2 x 8 panels:



The eltek 3.8Het is also a good match, so long as you configure it with 2 strings of 8.

 

[SibertSolar]

Fair point although I'd imagine those panels to output 50vdc pretty rapidly though. You're right though - the 3800tld is simply not an ideal match for those particular panels.

 

[Gavin A]

Installer yet it has fell on our feet to sort it out, we have installed 100s of systems and have never witnessed a Max voltage going anywhere near the MPP max, have you?

didn't you / your system designers realise that the voltage on those panels is around 50V vs 30V on the more standard 250Wp panels?

I suppose using the Diehl's with the wide voltage range maybe lulls you into a false sense of security on that front.