Your savings come from the grid electricity you no longer buy, plus any credit for surplus energy you export (net metering). The higher your electricity tariff, the more each solar unit saves you.
Three things drive your savings the most: your tariff (price per unit), your system size relative to your usage, and how much energy you use during daylight — daytime use is offset directly by solar, which is the cheapest saving of all.
A well-sized system commonly cuts a large share of a typical bill. Try our solar savings calculator with your own bill to get a realistic estimate for your home.
This is general guidance — figures vary by location, tariff, equipment and installer. Always confirm details for your own home before deciding.