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The limit is actually a current, not a power, so not knowing the maximum current you expect, I can't comment. The Wiki gives the max. current as 19.2 A. However, it's easy enough to add a wire-ended resistor in parallel with the existing burden to reduce the sensitivity, then if you have a programmer you can change the calibration inside the emonTx, otherwise you can apply a correction in emonCMS.

Don't get sucked in to the micro inverters nonsense.  I have Tigo micro inverters on one system, and it performs no different to the other system that just relies on the SMA GlobalTrack.

The micro inverters were a waste of £1000 IMHO.

Don't get sucked in to the micro inverters nonsense

Have to disagree with ya there. The M-Is don't have the shading issues a string inverter has. Of course if you're lucky enough to not have any shading issues, macht nichts.

If one of your modules takes a hit from a hailstone large eough to break it, you don't lose the entire string. Same goes for when the birds decide to "decorate" a module. In that case you wouldn't "lose" the entire string, but the "output" from the whole string will suffer because of the "affected" module.

Another thing you get is scalability. I started out with 4 modules, and added as budget allowed, till I got to 40.

Not impossible to do with a string setup, but it can be expensive.

The one thing I don't use is Enphase's Envoy monitor. Instead, I went with an OEM system, as I didn't care about module level monitoring.

I have 30 Enphase M215s and 10 M250s, and couldn't be happier with them.

Bill

Bill,

do you get one or 2 modules dropping out for a few seconds on your system? I'm trying to tie down a problem I see in EMONCMS whereby the output of one or 2 modules drops for 5 seconds and then is back 5 seconds later. I've just changed to Enphase Micro's from Renesola to see if it goes away.

Cheers

Kevin

 Hello Kevin,

I've not seen any dropouts other than the ones caused by adding modules, wiring changes, commercial power failures or other times when I've shut parts of it off for one reason or another. It's been rock solid the entire time.

I monitor my PV array with an OEM system and a TED 5000. I look at the production graphs every day and have never noticed any dropouts other than those mentioned above.

Regards,

Bill

Are you able to monitor your voltage at the time of the dropouts?  A common cause of inverter drop-outs here is because they've hit their Vmax trip point, then they slowly come back on-line in the hope that the voltage (or line impedance) has dropped.  I think local regulations here require them to drop-out at 255V, although many installers leave them set to their factory defaults of about 270V (much to the dismay of the people in charge of grid voltage regulation).

That grid impedance (including the impedance between your inverter and the street)  that often causes a voltage drop when you turn a big load on, works in the other direction when you're a producer.  It's possible your inverters are seeing a higher voltage then what's out on the street.  Whichever inverters have a slightly lower trip voltage (due to calibration variation) will trip first and the fact that they're no longer producing might be enough to lower the voltage just enough to avoid the rest tripping.

Kevin,

My Enphase micros wont come back on-line for 5 minutes once tripped. Did your Renesolas behave likewise?

Yes, I agree 5 seconds seems way too fast to be coming back on-line after a trip fault.

Apologies for not updating this for a while. As it stands I was able to upgrade from the 250W Renesola Micros to 10 x Enphase M215's and 2 x Enphase M250's. Initial results seemed to have more dropouts until a call to their support line got me later firmware and the dropouts I think have gone since then. I also have slightly more peak power despite the lower ratings of 10 of the inverters.

The Renesolas took anything from 10 seconds to 2 minutes to come back online and just switching the garage fluorescents on was enough to drop them. The Enphases seem much better, and unlike Renesola they actually support their products!

Soon I'm installing a dedicate 4 Channel EMONTX just for the array so I'll know for definite and I'll update this thread again with the results, as well as the average AC voltage which is usually around 240v rather than our nominal 230v

If you're in the UK, the voltage will still be centred on 240 V. And I don't see that changing any time soon.