Understanding your true effective rate
Why the advertised discount isn't the whole story
A provider advertising a 10% discount is telling you about the rate before any monthly fee gets added. Once a flat fee is spread across your subscription's annual kWh, the real discount you're getting can be noticeably smaller, especially on a modest-sized subscription. Compare this against the credit rate vs utility rate tool to see how the underlying rates line up. Check the DSIRE database for your state's standard credit rate policy, since a subscription's true value depends heavily on that baseline.
How fee impact scales with subscription size
A $5 monthly fee works out to $60 a year. On a 10,800 kWh subscription that's about half a cent per kWh, barely noticeable. On a 2,000 kWh subscription that same $60 works out to 3 cents per kWh, which can eat most or all of a modest discount. Always check your effective rate at your actual subscription size, which you can pin down with the subscription size calculator. A financed rooftop system has its own cost-per-watt figure that behaves the same way, covered by the financing cost per watt calculator.
Using the effective rate to compare offers fairly
Discount percentage alone can be misleading when providers structure fees or credit rates differently. Converting every offer to a single dollar-per-kWh effective rate strips out those structural differences and lets you compare on equal footing, the same way you'd compare gas prices at different pumps. The cost per kWh produced calculator runs this same normalization for a rooftop system.
What to check if your effective rate looks worse than expected
If your effective rate comes out close to or above your utility rate, double check the fee amount and confirm it's monthly rather than annual, since that's a common source of confusion. Also confirm the discount applies to the full credit value and not to some smaller base amount. Compare your result against the subscription savings calculator for a full dollar picture. The Department of Energy's community solar basics guide recommends getting the fee structure spelled out clearly before you enroll, exactly to avoid this kind of confusion.