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Annual credit and bill
Community & shared solar
Community solar credit rollover calculator
See how your credit balance builds and drains across a full year, so seasonal swings look expected instead of alarming.
How it works
Two steps to your balance projection
Step 1
Enter your annual credit and bill totals
Check the credit allocation estimator for a monthly breakdown if you don't have your annual credit figure yet.
Step 2
Pick the month you plan to start
Your starting month determines where on the seasonal curve your projection begins, which shifts the shape of the balance trajectory even though the underlying yearly pattern stays the same. See the enrollment timing calculator for how this same timing affects your first-year net savings.
Understanding your rollover balance
Why the balance moves in a predictable seasonal pattern
Solar production runs higher in summer and lower in winter, so a subscription sized to match your annual usage naturally builds a surplus during high-production months and draws it down during low-production months. This up-and-down pattern repeats every year and isn't a sign that anything is wrong with your subscription, and the underlying monthly figures come from the same seasonal model used in the credit allocation estimator. Check the DSIRE database for your state's specific rollover rules, since some states set a minimum carryforward window by regulation.
What a negative balance actually means
A negative balance simply means your bill for that month exceeded the credit available, not that you owe the provider anything extra. You pay your utility for the uncredited portion as usual, and the balance typically recovers as production increases again in the following months. A grid-tied rooftop system under net metering handles this same monthly true-up differently, as explained in the net billing versus net metering comparison.
How this connects to expiration risk
This tool shows the balance trajectory assuming no expiration limits how long banked credit stays valid. If your utility does enforce an expiration window, check the credit expiration calculator to see whether any of your peak-season surplus is actually at risk of being forfeited before you can use it. For the official wording, see the Department of Energy's community solar basics guide.
Using this to set expectations with your provider
Knowing roughly when your balance will peak and dip in advance makes it easier to interpret your monthly statements without confusion. If your actual balance looks meaningfully different from this projection, that's worth raising with your provider, since it could point to a billing lag issue covered in the billing cycle alignment tool. The negative bill credit rollover calculator covers the equivalent mechanic for an owned rooftop system. The Department of Energy's community solar basics guide recommends clear, plain-language billing disclosures as a baseline consumer protection worth expecting from any provider.
Questions
Frequently asked
The balance tracks the running difference between the credit your subscription generates each month and the bill amount that credit gets applied against. A positive balance means you have banked credit available, while a negative balance means your bill exceeded available credit that month.
Yes, since solar production is seasonal, a subscription sized to match annual usage typically runs a deficit in winter months and a surplus in summer months. As long as the annual total balances out, month-to-month swings are expected rather than a sign of a problem.
No, a negative balance in this context simply means your bill wasn't fully offset by credit that month, not that you owe the community solar provider anything extra. You still pay your utility for the uncredited portion, same as any month without a subscription.
Your starting balance point on the seasonal curve depends on when you enroll, so a January start might show an early dip before the summer surplus builds, while a June start might show a stronger early balance that tapers through winter. The overall seasonal pattern is the same either way, just shifted to start at a different point.