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Community & shared solar
Community solar vs grid only: 25 year comparison
Project a full 25-year horizon, the same window used for rooftop solar payback, to see the long-term picture clearly.
How it works
Two steps to your 25-year projection
Step 1
Use a realistic utility growth rate
Check your utility's recent rate history for a specific figure rather than guessing, since this assumption matters more the longer the projection window runs. See the vs doing nothing comparison for a shorter-horizon version of this same math if you want a quicker check first.
Step 2
Enter your subscription's actual escalator, or 0 if none
This single figure has an outsized effect on a 25-year projection. Check the escalator rate calculator for a detailed year-by-year breakdown of how it plays out.
Understanding the 25-year comparison
Why this matches rooftop solar's typical timeline
25 years is the standard assumed lifespan for a rooftop solar system, so using the same window for community solar puts the two options on comparable footing. Comparing a 10-year community solar projection against a 25-year rooftop payback estimate would understate one option's long-term picture relative to the other. The 25-year lifetime savings calculator runs this same horizon for a rooftop system directly. The Department of Energy's community solar basics guide covers the bill-credit mechanism this comparison is built around, useful background if it's a new concept.
Why the escalator matters more here than in a shorter comparison
An escalator's effect compounds every year it applies, so a small annual increase that looks negligible in year one can meaningfully erode or even reverse your savings by year 20 or 25. This is the same mechanic covered in the escalator rate calculator, just extended to the full rooftop-comparable horizon here. Current figures live on the Department of Energy's community solar basics guide, which updates them when the program changes.
Why most subscribers won't actually see the full 25 years
Most community solar contracts run considerably shorter than 25 years, commonly somewhere between 5 and 20 years, so this projection is best treated as a planning benchmark rather than a literal forecast of your specific situation. It's most useful for comparing against a rooftop solar decision on equal terms. A financed rooftop system's own term length affects this comparison too, covered by the loan term comparison tool. Check the DSIRE database for typical contract lengths offered in your state, since availability and standard terms vary by program.
What to do if the long-term picture looks weak
If this projection shows savings shrinking or turning negative, check whether a price-locked offer or a shorter contract term better fits your situation. The price lock value calculator quantifies exactly what avoiding the escalator would be worth, and the vs installed payback crossover calculator is worth checking if rooftop solar is also on the table. The DSIRE database lays out the same rules from the regulator's side.
Questions
Frequently asked
25 years is the typical usable lifespan assumed for a rooftop solar system, so using the same horizon for community solar makes the two options directly comparable on equal footing. A shorter comparison window can understate or overstate community solar's long-term value depending on the specific terms involved.
Yes, if the subscription has an escalator that grows faster than the utility rate over a long enough period, cumulative savings can shrink and eventually turn negative even with a solid starting discount. This is more likely to show up over a full 25-year projection than a shorter one, since the effect compounds over time.
Not necessarily, most subscription contracts run much shorter, commonly 5 to 20 years, so a full 25-year projection is more of a planning benchmark than a literal expectation. It's useful for comparing against rooftop solar's typical horizon even if your actual contract term is shorter.
Check your subscription's specific escalator rate and compare it against realistic utility rate growth expectations for your area. If the escalator is high relative to expected utility growth, a shorter contract or a price-locked offer may be a better fit than a long-term commitment.