How to Use the Solar Self-Consumption Calculator
If you have rooftop solar, the share of generated electricity you use directly — your self-consumption rate — drives most of your real savings. Excess power can be sold back to the grid, but net metering credits are often worth less than the retail rate you'd otherwise pay, so using power as you generate it is usually more valuable. This calculator takes your daily generation, total daily usage, and the share of usage that happens during daylight hours to estimate self-consumed energy, the self-consumption rate, and expected savings.
The daytime usage share reflects how much of your electricity use — laundry, dishwashers, air conditioning — happens while the sun is up. Households where everyone is out during the day tend to have a lower share and a lower self-consumption rate, while remote workers or stay-at-home households typically see both figures rise.
The simplest way to raise your self-consumption rate is shifting high-load activities like laundry, drying, or EV charging to the roughly 10am-4pm window when panels produce the most. Adding home battery storage lets you bank excess daytime power for nighttime use, and can push self-consumption above 80% for many households.
Frequently Asked Questions
We multiply your total daily usage by the daytime consumption share to estimate energy you could use while the sun is out, then compare it to your generation and take the smaller value as self-consumed energy. Dividing that by generation gives the self-consumption rate.
Shift high-usage activities like laundry, dishwashing, and EV charging to daytime hours (roughly 10am-4pm) when panels produce the most, or add home battery storage to save excess daytime power for use at night.