Comparing Solar Quotes in 2026: Start with the Production Assumptions

1. Give every bidder the same starting information

Collect at least 12 months of utility bills, including electricity use in kilowatt-hours, not just dollars paid. Where available, download hourly or shorter-interval usage data from the utility. Annual consumption tells installers how much energy you use; interval data helps show whether you use it while panels are producing. A household that runs air conditioning in the afternoon can have different solar economics from one that uses most electricity after sunset.

Separate existing consumption from planned changes. An electric vehicle, heat pump, addition or departing household member can change the right system size. Ask each installer to model the same baseline, with future loads shown separately. Also provide consistent information about roof age, planned tree work and any battery requirement. Otherwise, two reasonable designs may solve different problems rather than compete on price.

• Share the same billing history and identify the utility, rate schedule and any separate electricity supplier.
• List future electric loads with expected timing; do not let every bidder invent a different usage increase.
• Request a solar-only cash proposal first, with batteries, financing and optional work itemized separately.
• Ask whether the proposal assumes a rate-plan change, and have the installer identify that plan by name.

2. Normalize system size before comparing output

System size is power capacity, usually quoted in kilowatts of direct current, or kW DC. Production is energy generated over time, usually annual kilowatt-hours, or kWh. Those are not interchangeable. Confirm that every quote uses DC capacity, then divide estimated first-year production by that capacity. The result, kWh per installed kW, is a useful comparison metric, not a guarantee or a universal performance benchmark.

In this illustrative comparison, Quote B promises more electricity despite having fewer panels’ worth of capacity. That could reflect better roof placement, different equipment or a more optimistic model. Ask for the explanation before treating its output as a bargain. A larger array can have lower production per kW if its additional panels occupy a shaded or less favorable roof plane.

Also compare inverter AC capacity, panel locations and expected clipping, when potential panel output exceeds the inverter’s conversion limit. Some clipping can be an intentional design trade-off, not a defect. Have each bidder explain how its equipment choices affect annual output and total price rather than assuming that the highest equipment rating delivers the best value.

3. Ask what the production model actually assumes

A production estimate should be traceable to a roof layout and a documented set of inputs. Ask for monthly output, not just an annual total, plus roof direction, tilt, weather data source and modeled losses. Seasonal output matters because electricity prices, household demand and export-credit treatment can vary through the year. Confirm whether the number represents expected first-year AC energy after system losses rather than an equipment-label calculation.

Shading deserves particular attention. A satellite image may miss a growing tree, chimney shadow or obstruction on a neighboring property. Ask how shade was assessed and whether a site visit changed the design. Module-level electronics can reduce some mismatch losses, but they cannot recover sunlight that never reaches the panels.

Use an independent tool such as NREL’s PVWatts as a reasonableness check with comparable inputs, not as a substitute for a detailed shade assessment. If estimates differ materially, have bidders reconcile the assumptions. Then distinguish an expected production figure from a contractual production guarantee, including any exclusions and remedy.

• Request shade losses by roof plane and clarify whether tree trimming is assumed.
• Check allowances for snow, dirt, temperature, wiring, equipment downtime and inverter losses.
• Ask what annual degradation rate reduces production in later years.
• Confirm whether future tree growth or required maintenance appears anywhere in the projection.

4. Value electricity using the actual utility rules

Solar electricity has two main destinations: It serves household loads or flows to the grid. Electricity consumed at home generally avoids applicable variable charges. Exports receive whatever compensation the tariff allows, which may be different from the retail purchase price. Do not accept a model that multiplies every solar kWh by the bill’s average cost unless the installer demonstrates why that calculation fits your tariff.

Independently verify the current tariff with the utility and, where relevant, the state utility commission or municipal or cooperative rate authority. Check eligibility for new customers, application deadlines, grandfathering provisions, system-size limits and any required time-of-use plan. A neighbor’s older net-metering arrangement may not be available to you. Confirm separate supplier treatment if your electricity supply and delivery come from different companies.

Ask how credits carry forward, when accounts are reconciled and whether unused credits expire or receive a different payout. Fixed customer charges and some nonbypassable charges may remain. Under time-varying rates, match production and consumption by interval where possible; annual totals alone can conceal low-value midday exports and expensive evening purchases. For a battery proposal, require a separate dispatch model showing losses, usable capacity and the rates driving its projected savings.

5. Compare the gross cash price and identical scope

Request the full installed cash price before tax credits, rebates or projected electricity savings. Divide that price by DC watts to calculate dollars per watt, but use the metric only after aligning scope. A straightforward roof installation is not equivalent to one requiring a service-panel upgrade, structural work or difficult access. Separately price batteries so their cost does not distort the solar comparison.

A financing quote is a different product. Compare the cash price with the financed principal, then review the annual percentage rate, term, fees and total payments. Some offers pair a low advertised interest rate with a higher financed price. Check whether payments change if you do not make an assumed lump-sum payment. In 2026, an outdated federal-credit assumption can make that structure particularly misleading.

• Confirm permits, interconnection applications, monitoring and required electrical work are included.
• Identify allowances or exclusions for roof repairs, trenching, structural reinforcement and utility upgrades.
• Compare equipment models, workmanship coverage, roof-penetration terms and labor coverage for warranty claims.
• Ask who pays to remove and reinstall panels for future roof work.
• Keep leases and power purchase agreements separate from purchase bids; examine escalators, transfer terms, maintenance responsibilities and buyout provisions.

6. Recheck incentives under the current 2026 rules

Do not assume a new homeowner-owned installation completed in 2026 qualifies for the former 30% federal residential clean energy credit. Federal legislation enacted in 2025 ended the Section 25D credit for expenditures made after December 31, 2025. For this purpose, an expenditure generally is treated as made when original installation is completed; paying a deposit in 2025 does not by itself preserve eligibility for a 2026 completion.

Check current IRS guidance and your specific facts with a qualified tax professional, especially for projects spanning years. Previously earned credit carryforwards are a separate issue from eligibility for a new installation. A proposal that automatically subtracts a homeowner federal credit from a 2026 project needs correction before its net price or payback is useful.

Third-party-owned systems may involve business tax provisions, but those incentives belong to the eligible owner, not automatically to the homeowner signing a lease or power purchase agreement. Ask how any claimed benefit affects your contract price without treating it as your personal refund. Verify state, utility and local programs directly with their administrators. Check funding availability, reservation requirements, installation deadlines, approved equipment or contractors, tax treatment and whether incentives can be combined. Treat renewable energy certificate revenue separately: Prices, ownership rights and contract obligations can change its value.

7. Rebuild payback with a conservative common scenario

Once the inputs align, ask each bidder to rerun the economics using identical utility rates, export compensation, electricity-price escalation and incentive eligibility. For a purchase, a simple payback calculation divides net upfront cost by estimated annual net savings. It is only a screening measure: It does not fully capture financing, changing output, future costs or the timing of cash flows.

Request both a first-year bill estimate and a year-by-year cash-flow schedule. Include remaining utility charges, maintenance assumptions, potential inverter replacement, monitoring fees and any added insurance cost. Show loan payments separately from operating savings so a lower utility bill is not confused with positive household cash flow. For batteries, include any assumed replacement rather than extending initial performance indefinitely.

Finally, test a less favorable case: lower production, weaker export value and no retail-rate escalation. Ask what happens if interconnection delays shift the operating date or incentive eligibility. The strongest proposal is not necessarily the one with the shortest printed payback. It is the one whose roof-specific output, documented price and independently verified rules still make sense when optimistic assumptions are removed.