We have an array of 16 solar panels and have noticed that the yield has
dropped a fair bit in the past 8 months or so. There is an error showing
on the inverter referring to the battery pack.

Now, assuming the fault is in the battery pack, would that cause the
system to register less energy production than if the battery was
working OK?

The battery pack has two banks, and one bank seems to be working properly.

The voltage from the two banks of solar panels is within +-8v of each
other, sometimes one has more, sometimes less. The current however is
showing about half on one bank compared to the other. These measurements
are taken from the inverter data.

I'm guessing that one bank of panels feeds one bank of the battery pack,
and the other solar panel bank feeds the other battery bank.

Could the battery fault cause the inverter to accept less power from one
bank of solar panels?

I would have thought that if the inverter was smart enough, it would
just divert the power to the grid, or house load.

We are going to get the original installers back to sort it out, but in
the mean time I'm interested in finding out how these things work (or
don't in this case!).

--
Biggles