Savings and payback
See what your year-end balance is actually worth, including the important gap between the low rate paid for surplus and the full retail rate charged for deficits.
For planning purposes only, not financial or tax advice; confirm figures with a licensed installer or tax professional before making a purchase decision.
How it works
Step 1
Use the ending balance from the bill credit rollover calculator, positive for surplus or negative for a deficit.
Step 2
The tool shows what a surplus is actually worth at the lower compensation rate, compared to what it would be worth at full retail, so you can see exactly how much value the rate gap costs, a factor worth weighing alongside the zero dollar bill calculator.
Utilities typically credit monthly production at your full retail rate, but any leftover surplus at the annual true-up gets cashed out at a much lower net surplus compensation rate, often $0.02 to $0.08 per kWh, compared to a typical retail rate around $0.16. That's a meaningful asymmetry worth understanding before assuming excess production is worth as much as avoided usage, as covered on the bill offset percentage calculator. The figures here line up with the EIA.
For 3,490 kWh of year-end surplus, the same figure from the bill credit rollover calculator's surplus scenario, cashing out at a $0.05 net surplus rate yields about $175, compared to roughly $558 if it were paid at the full $0.16 retail rate, a loss of nearly $384 in value simply from the rate difference. The System size for net metering cap limit is the quickest way to check whether the system size behind this estimate fits your roof and usage.
Deficits are billed at your full retail usage rate, not the lower surplus rate. This asymmetry is exactly why oversizing a system to bank large surplus credits often doesn't pay off as well as it might first appear, since the value you gain on the surplus side is worth meaningfully less than the value you'd lose on the deficit side.
It reinforces sizing closer to your actual annual usage rather than deliberately overproducing. Since surplus is worth far less than avoided usage, a right-sized system generally captures more value per kWh of production than one designed to bank large credits, a principle worth applying alongside the low usage home savings calculator. For the official overview, the US Department of Energy's homeowner's guide to going solar covers buying, leasing, and system sizing.
To look at this from another angle, see the Annual kWh output estimator or the System size for net metering cap limit. For the latest US electricity price data, see EIA. The production figure behind this estimate comes from the Annual kWh output estimator, which models output for your location and roof.
Questions
Utilities typically credit monthly production at your full retail rate, but any leftover surplus at the annual true-up gets cashed out at a much lower net surplus compensation rate, often $0.02 to $0.08 per kWh, compared to a typical retail rate around $0.16.
For 3,490 kWh of year-end surplus, cashing out at a $0.05 net surplus rate yields about $175, compared to roughly $558 if it were paid at the full $0.16 retail rate, a loss of nearly $384 in value simply from the rate difference.
No, deficits are billed at your full retail usage rate, not the lower surplus rate. This asymmetry is exactly why oversizing a system to bank large surplus credits often doesn't pay off as well as it might first appear.
It reinforces sizing closer to your actual annual usage rather than deliberately overproducing. Since surplus is worth far less than avoided usage, a right-sized system generally captures more value per kWh of production than one designed to bank large credits.