Understanding this comparison
Why staying with your utility alone is the baseline
This comparison treats your current bill as the do-nothing option, since that's what happens if you never enroll in community solar at all. Every dollar saved from a subscription discount comes directly off that baseline, which is why the comparison is almost always favorable toward subscribing, assuming the discount holds. A rooftop system's payback calculation starts from the same do-nothing baseline, covered by the quick 5-minute system size estimator.
What this simple version leaves out
This tool assumes a flat bill and flat discount for the whole comparison period, which is a simplification. It doesn't account for utility rate increases, which would make the savings even larger in dollar terms over time, or for any subscription price escalator, which would slightly reduce it. For that level of detail, use the full subscription savings calculator. A quick rooftop payback estimate has the same simplified-versus-detailed tradeoff, covered by the quick 2-minute payback estimator.
When this comparison doesn't favor subscribing
The only scenarios where this comparison doesn't favor subscribing are when the discount is 0%, which shouldn't happen with a legitimate offer, or when a cancellation fee outweighs the savings if you need to exit early. Check the cancellation fee calculator if you're worried about needing to exit your contract before the term ends. The Department of Energy's community solar basics guide lists a discount off your bill as a defining feature of a legitimate program, worth confirming if an offer looks unusual.
Moving from a quick look to a real decision
Once this comparison confirms subscribing looks worthwhile, the next step is finding out if community solar is actually available in your area and comparing real provider offers. Start with the eligibility checker tool. Check the DSIRE database too for any state-specific programs that might improve on the general numbers used in this quick comparison.