How to compare the monthly cost of solar
Use a before-and-after ledger that separates utility charges, solar payments and uncertain assumptions.
Updated October 23, 2026
Start with the bill you actually pay
Collect a useful range of recent electricity bills and identify both usage and charges. A single unusually high or low month can distort the comparison. Note whether a recent household change is already reflected in those records. Keep personal account details in your own files; they are not needed in a public planning worksheet.
Write down which parts of the current bill could change and which might remain. Ask your utility about the rules that apply to your service, including credits for exported electricity. Do not assume an exported unit receives the same value as an imported unit, or that solar removes every charge.
Build a complete after-solar ledger
Place the estimated remaining utility bill next to the proposed solar payment and any other recurring costs. Compare the combined total with the same period before solar. This is a way to organize a scenario, not a promise that the scenario will occur.
Keep the full project price separate from the monthly payment. The CFPB advises consumers to ask for the cash price and compare financing offers rather than relying only on a sales presentation. Read the actual payment schedule, charges and any conditions that could change the amount due. Ask the provider to explain unclear differences in writing.
Test the assumptions that move the result
Review expected production, electricity use, utility rates, export treatment and payment terms one at a time. Ask to see what happens when an important assumption is less favorable. A wide result range can be more useful than a precise-looking number that hides uncertainty.
Treat incentives as a separate scenario until current program rules, timing and your circumstances have been checked. Do not spend an assumed rebate or tax benefit before understanding whether and when it applies. A general calculator does not determine personal tax eligibility or guarantee that a program will remain available.
Use the comparison to ask better questions
Keep a simple record of the before cost, modeled after cost, source dates and unanswered questions. When comparing proposals, use the same usage period and identify differences in equipment, financing and service responsibilities. Ask what is included rather than assuming similar monthly payments describe similar offers.
The next useful decision is whether the scenario deserves a detailed property and contract review. A modeled reduction in electricity spending is not proof of an installed system’s performance, an approved loan or a completed saving.
Sources and further reading
Explore a scenario for your home.
Bring your bill and questions to the existing QuoteOtter property analyzer. Availability and the assumptions shown determine what the report can tell you.
Explore my solar optionsContinue to QuoteOtter Solar Intelligence. Planning estimates are not installation quotes.