Had solar and batteries installed mid-year 2025. Since about September / October, it appears that, once the batteries have reached their full charge, the solar panels electricity generation falls away, to basically just meet the house electricity usage. Even on a fine, sunny day, there is a steep drop in solar generation. As a result, there is minimal electricity being returned to the grid. Is this usual? Who should I talk to about this? AGL, SA Power Networks, my battery installer?