Your Electric Bill vs. Solar: Which Could Cost More Over the Next 25 Years?
Long-horizon comparisons are where energy decisions are actually made — and where the assumptions do most of the work. Here is how to build one honestly.
Twenty-five years is the horizon the solar industry uses because it roughly matches typical equipment warranty periods. It is also long enough that small assumptions compound into large numbers — which makes it the most useful and the most abusable timeframe in energy comparisons.
This article does not tell you which option costs less. It cannot: that depends on your house. What it does is show how a defensible comparison is constructed, so you can evaluate whether the one someone hands you is credible.
The two scenarios
Every long-term comparison reduces to the same pair.
Scenario A: continue purchasing grid electricity
The household buys all of its electricity from the utility for the full period. Total cost equals annual consumption multiplied by the delivered price, summed across 25 years, with whatever rate assumption is applied.
Scenario B: a solar or home energy project
The household produces some of its electricity on site. Total cost equals the project cost — including any financing charges — plus the utility charges that remain, again summed across 25 years.
An illustrative example, with assumptions stated
The table below uses a hypothetical household. It is a demonstration of method, not a projection for any real property, and it is not a claim about what any homeowner will experience.
Stated assumptions:
- Hypothetical household using 12,000 kWh per year, with usage held constant.
- Starting delivered cost of $0.22 per kWh — an assumed figure for illustration, not a current published rate.
- Scenario A modeled twice: once with no annual change, once with an assumed 3% annual increase.
- Scenario B assumes a financed project with a fixed total obligation and residual utility charges of $30 per month, held constant.
- No incentive amounts are included, because eligibility and program values change over time.
| Line | Scenario A (0% change) | Scenario A (3%/yr assumed) | Scenario B (illustrative project) |
|---|---|---|---|
| Year 1 electricity cost | $2,640 | $2,640 | $360 residual utility charges |
| Year 1 project payments | — | — | Depends on structure and term |
| 25-year electricity total | $66,000 | $96,266 | $9,000 residual utility charges |
| 25-year project total | — | — | Total-of-payments, which must be supplied per project |
Notice what the table deliberately does not do: it does not fill in the project total. That number cannot be generalized. It depends on system size, equipment, roof complexity, financing terms and which incentives a specific project qualifies for. Any article that fills that cell with a statewide average is guessing on your behalf.
The variables that move the answer
Future rate uncertainty
Nobody knows what electricity will cost in 2051. Rates are set through regulatory processes and wholesale markets that respond to fuel prices, demand growth, infrastructure investment and policy. A comparison should show a range of assumptions rather than a single confident line.
Production degradation
Solar panels produce slightly less each year. Manufacturers typically publish a warranted production curve; a credible model applies that degradation rather than assuming flat output for 25 years.
Financing charges
On a financed project, interest is a real and often substantial part of the total. A comparison that shows the equipment price but omits the total-of-payments understates the project side.
Maintenance and equipment life
Panels are largely passive, but inverters generally have a shorter service life than the array and may need replacement within a 25-year window. Ask whether the model includes that.
Remaining utility charges
Even a well-performing system leaves fixed customer charges and any imported electricity on the bill. A comparison showing the utility cost dropping to zero is not describing how interconnected solar works.
Roof considerations
If the roof will need replacement during the analysis period, the cost of removing and reinstalling panels belongs in the model — or the roof work belongs at the front of the project.
Ownership structure and incentives
Who owns the system determines who claims applicable incentives, and that materially changes both sides of the comparison. Incentive programs and their eligibility rules change; use the rules in effect when the project is quoted.
How to read a comparison someone hands you
A trustworthy long-term comparison has a specific set of characteristics. If several of these are missing, ask why.
- Every assumption is stated in plain language, including the annual rate-change assumption.
- Both scenarios cover the same period and the same household usage.
- The project side shows total-of-payments, not just a monthly figure.
- Residual utility charges appear in the solar scenario.
- Production degradation is applied.
- Results are described as estimates, with a clear statement that actual results vary.
- There is a sensitivity view showing what happens if the rate assumption is wrong.
What This Means for NJ Homeowners
The only meaningful 25-year comparison is one built from your home's actual usage, your roof's actual geometry, your utility's actual charges and a specific project's actual terms. Everything else is a worked example — useful for understanding the method, useless for making a decision.
Solar does not save every homeowner money, and no responsible analysis claims otherwise. What a personalized model can tell you is whether the two scenarios are close, far apart, or clearly favor one direction for your particular property.
- Solar
- Electricity Rates
- Household Budget
