A solar proposal should remain undecided when the property, tariff, contract, or cash-flow evidence needed to evaluate it is missing. “Not yet” is a valid result; do not replace an unknown with a national assumption.
The roof or production evidence is incomplete
Confirm roof condition, usable area, orientation, shading, and any removal-and-reinstallation obligation before treating projected production as available. Model the actual address with NREL PVWatts or another documented site-specific study, and keep the result missing if the required roof inputs are unavailable.
The utility cash flows are unclear
Use the tariff that will govern imports, exports, fixed charges, and non-bypassable charges. A retail rate alone does not establish savings, and an export policy from another jurisdiction is not a substitute. Enter the documented first-year values in the Solar Savings Calculator, then use the owner ledger for later-year cash flows.
A sale or transfer is plausible
Check who owns the system and each obligation, whether a loan, lease, or PPA can transfer, what buyer qualification is required, and how payoff, buyout, removal, or property-security terms work. Do not assume an owned system, debt, lease, or PPA produces the same resale outcome in every market or contract.
The proposal depends on an unverified incentive or outcome
Identify the actual system owner, incentive program, jurisdiction, source event, eligibility evidence, household price schedule, and receipt timing. Provider tax treatment and the household's contract price are separate questions; a claimed provider benefit does not establish a household discount. Compare the written cash, loan, lease, and PPA schedules in the financing guide and four-scenario comparator. If a required term is absent, leave the result unmodeled.
Solar is one piece of a bigger household-finance picture. For decisions that touch your taxes, retirement timeline, or home equity, it can be worth talking to a financial advisor through a directory like AdvisorWorld — alongside primary sources such as DOE, DSIRE, and the IRS.