Check the export values against the published rates
Net billing tariff customers are paid for exported electricity based on its value to the electric grid, determined by the Avoided Cost Calculator, which quantifies the value of exports at different times of day based on the avoided cost to the utility of buying clean energy elsewhere.
The utilities are required to publish uniform machine-readable spreadsheets containing the retail export compensation rates on their respective websites. That makes the export values in your quote a checkable fact rather than a matter of trust.
Ask your installer which export values their projection uses and where those values came from, then compare against the published spreadsheet. Any discrepancy deserves an explanation, and asking at all changes how the rest of the conversation goes.
Look at the shape across the day and the year rather than an average. Averaging hides the variation, and the variation is precisely what determines whether a system, or a battery, pays.
Interrogate the self-consumption assumption
The second place a projection can be optimistic is in how much of your production it assumes you consume yourself. Electricity used as it is generated avoids a retail purchase, which is generally worth more than exporting it, so a higher assumed self-consumption share produces a better-looking result.
Whether that share is realistic depends on your household rather than on the equipment. Ask what share the model assumes and why, and ask to see the same system on a more conservative assumption.
The gap between the two tells you how much of the promised return depends on behaviour you have not yet committed to. That is worth knowing before signing, particularly if the case only works on the optimistic version.
Ask whether the production estimate was modelled for your specific roof, orientation and shading rather than a regional average, and ask for a shading assessment covering the whole year rather than the hour of the site visit.
What belongs in the contract
Get equipment specified by manufacturer and model number rather than by description. Model numbers are what make a warranty enforceable later and what let you compare two quotes on the same basis rather than on adjectives.
Establish who honours each warranty and for how long. Panels, inverter and workmanship are commonly covered by three different parties on three different terms, and a company that has left the market cannot support a workmanship warranty however well drafted.
Ask what the workmanship warranty covers on roof penetrations specifically. Leaks around mounting hardware are the most common physical failure in residential solar and they typically appear a few years in, well after the installation has been forgotten about.
Get the production estimate into the contract along with what happens if actual production falls materially short. An estimate that appears only in a sales presentation is not a commitment, and knowing whether anyone stands behind it changes how much weight it deserves.
What changed federally, and the battery incentive that remains
The 30 percent federal Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025. A cash or loan purchase made now receives no federal credit, and a quote that still applies it is overstating your return substantially. Check any projection line by line rather than trusting a summary figure.
Section 48E survives at 30 percent and is available to third-party owners of residential systems under leases and power purchase agreements. The credit still exists, it simply no longer flows to a homeowner who buys the system. Expect lease providers to lead with that, and ask what they claim and what of that value actually reaches you in the rate offered, then confirm with a tax advisor.
California's Self-Generation Incentive Program continues to provide incentives for battery storage installed on the customer's side of the meter, including systems that can function during a power outage. Its Equity and Equity Resiliency categories are aimed at lower-income, medically vulnerable and at-risk for fire communities.
Depending on the category a customer qualifies for, the incentive is $850 per kilowatt hour under Equity or $1,000 per kilowatt-hour under Equity Resiliency. Applicants have one year after reserving funds to meet programme requirements, which include enrollment in a qualified Demand Response program, and further criteria are in the SGIP Handbook. Ask whether you might qualify and confirm with the programme rather than treating a sales answer as final.