Fronius Symo 5.0.3-M Weird MPP Behaviour

[matthewoswald]

Hi All,

Have recently moved into a house with a 5kW Fronius Symo installed with 5.8kW worth of panels on the roof 11 panels face east, 11 panels face north. Have noticed that when trending power output, we never manage to get much above 4kWhr for any reasonable duration of time during full sunlight. Scolling through the display on the unit, the MPP Currents appear to be behaving wierdly, as in they will regulary drop to 0 across both channels.

Is this expected behaviour?

Any advice would be appreciated. (can only appear to upload 1 image currently)

Thanks,
Matt

[grannos]

Hi Matt,

I have the same model inverter with 20 panels [ 12 N + 8 E ] 6.6kW. I have the latest firmware installed in my inverter. My inverter is NOT export limited in any way so all 5kW can get sent to the grid if the house load falls to zero, which it doesn’t.

I used the solar web portal to exam the DC current of the two strings. The only time I am seeing ZERO current is when the system is not in operation i.e. nighttime. My inverter will sit on around 5050W output for several hours at a time on these current sunny [ Perth ] days.

Is you MPP1 string the EAST facing string? It shows the highest current earliest in the say. I would have expected though that the NORTH facing string would take over in the afternoon. What do the two POWER curves looks like for the same date.

Grannos

[matthewoswald]

Hi Grannos,

Thanks for the reply. Power curves for the same day is below:

Have attached a plan view of the house from google maps. I would need to check which string belongs to which MPP. Its very strange, my feeling is that there is something Higglety Pigglety with the settings of the inverter, but I am not smart enough to know what…

Thanks,
Matt

[matthewoswald]

[matthewoswald]

Total Power for that same timespan…

[B-Man]

Is there any inverter issues?
What’s the dc voltage?
It looks like mppt1 string is barely working.

[grannos]

Hi Matt, I concur with @B-Man that something is amiss with MPP1 or the software / hardware that manages the two strings. Have you checked the inverters’s LCD for any error messages or error codes? Have you check the inverter’s log via the Solar Web interface? You could try shutting down the inverter and restarting it. It may be just some gremlin that goes away.

There are other people who inhabit this forum who are much better qualified to discuss potential hardware or electrical problems - especially on the DC side of things.

[Edit] I suppose there is a possibility that a single panel on the underperforming string is causing the problem. Can you safely inspect that panels for any signs of a gross problem like condensation, cracked glass, or other signs of discolouration? Is there any weird shading affecting the under performing string? A large branch being blown back and forth sweeping a panel ( or panels ) with shade. [/Edit]

Grannos.

[matthewoswald]

Thanks Team,

I am running a test over the next 2 days, will isolate each bank for 24 hours and review the data.

Matt