I’m trying to understand how the “saved” figure is calculated.

In January I consumed 385kWh, imported 162kWh and exported 635kWh. My export price is 12c, my import tariff (single rate) is 20.16c and my supply charge is 98.67c.

I calculate my cost was -$13, which pvoutput shows as the balance. I calculate my cost without solar would have been $108, giving a saving of $121. However pvoutput shows the saving was only $45.

How is $45 calculated? Is my $121 calculation incorrect, and if not can I get pvoutput to calculate the same figure?

https://pvoutput.org/aggregate.jsp?id=71165&sid=66005&v=1&t=m

Thanks,

Hamish