We just installed a 5.06Kw system with a sunny island battery backup. The system consists of 2 strings of 11 panels Solar world SW230mono, 1 SB5000US, 1 SI5048U, 2 battery banks of 4 105Ahr Deka gel mat batteries.The array is oriented aprox. 73d NNE, at a 22d angle.The panels production is excellent 8A, 330V per string.
After taking into account the orientation, and temp. derating, the array should be producing about 3.3KW/hr, it is producing at noon around 1.7kW
We checked the connections for polarity problems and everything is connected correctly, throuhg the DC disconnect.
We checked the electric input to the Sunny boy after the connections on the DC side and they were aprox 15.6A, 330V
The output on the AC side was aprox. 237 V and 8.2 A
We got these readings while grid tied, we had isolated the sunny island from the connection. I would appreciate any suggestions on how to fix this problem.

Its not likely, but when the inverter is in off grid mode an increase in frequency will limit the output of the inverter. What is the grid frequency?

What are the outputs on the display?

The grid freqency is supposed to be 60Hz, last time I checked it was around 59Hz. The output registered on the inverter at noon without clouds was around 1.8Kw/hr & 330V.

I'd appreciate any pointers you have

what if you shut down all the other breakers from your main except the inverter.

Try disconnecting one string and seeing if there is a drop in power. Then try the other string on its own. If they are both putting out around 1.7kW This could indicate the inverter is limiting the output power.

You can record the voltage in each case (once feeding the grid) to see its mpp voltage. Hopefully they are approximately the same. Then connect both again and see if the mpp voltage is the same. If the inverter is limiting power, then there should be a signicant change when they are both connected.

If the inverter is limiting power, you may need to check the parameters of the inverter. If nothing is out of order you should contact SMA tech support.

Thanks, I'll try this approach