The best solar quote is not automatically the lowest total or the smallest monthly payment. To learn how to compare solar quotes, first make every installer answer the same questions with the same 12 months of electricity use. Then compare the design, production model, cash price, financing cost, equipment, project scope, warranties, and installer accountability side by side.
For a South Carolina home, add two checks that national guides often miss: which utility rules the proposal models and whether the people doing the electrical and roof work hold the required state credentials. A polished savings graph cannot make up for a mismatched utility assumption or an unclear contract.
Start with one solar quote comparison sheet
Do not compare proposal covers. Build a one-page worksheet and copy the underlying facts into it. If an installer cannot provide an item in writing, mark it “not stated” rather than filling the gap yourself.
| Comparison field | Quote A | Quote B | Quote C | Why it matters |
|---|---|---|---|---|
| Last 12 months of usage used (kWh) | Different starting data produces different designs | |||
| Solar array size (kW DC) | Normalizes systems with different panel counts | |||
| Year-one production (kWh) | Shows what the design is expected to generate | |||
| Roof planes, tilt, azimuth, and shade assumption | Explains much of the production difference | |||
| Solar-only cash price before incentives | Creates a clean price baseline | |||
| Cash price per watt | Compares different system sizes | |||
| Panel and inverter make/model | Lets you verify specifications and warranties | |||
| Battery make/model, usable kWh, and power (if any) | Separates backup capability from solar capacity | |||
| Included work and exclusions | Exposes adders and change-order risk | |||
| Utility/export-credit assumption | Shapes the savings model | |||
| Workmanship, roof, product, and production coverage | Shows who is responsible after installation | |||
| Cash/loan/lease terms and total payments | Reveals the actual long-term cost |
South Carolina’s Energy Office says a solar bid should identify total start-to-finish cost, equipment, labor, permits, taxes, model numbers, warranties, expected operating costs, projected generation, and financing options. That official homeowner solar guide is a useful completeness check, although any incentive figures in an older guide should be verified separately before you rely on them.
Ask each company to revise its proposal if the worksheet has blanks in the system size, production, cash price, equipment, or scope rows. Those are not minor details. They are the basis of the purchase.
Compare system size, not the number of panels
Panel count is a poor comparison because panel wattages differ. Compare the array’s total direct-current rating, expressed in kilowatts DC (kW DC).
Use this formula:
Number of panels × panel watts ÷ 1,000 = system size in kW DC
Two quotes can use different panel counts and still propose nearly the same array size. A higher-wattage panel can be useful where roof area is limited, but the largest individual panel number does not make a proposal better by itself. The inverter, layout, shade, roof orientation, and electrical design all affect the result.
Next, confirm that every installer used the same electricity history. Provide 12 complete months in kilowatt-hours—not just an average dollar bill. Note planned changes such as an EV, heat pump, addition, pool, a person moving in or out, or major efficiency work. A quote based on last year’s usage and a quote that includes a future EV are solving different problems.
If one system is much larger or smaller, ask for a written explanation. Valid reasons may include usable roof area, shade, a different target offset, electrical constraints, or utility program limits. “More panels means more savings” is not an adequate design explanation.
Test each production estimate
System size is power capacity; annual production is energy. A proposal should state both:
- kW DC: the rated size of the solar array.
- kWh per year: modeled electricity production in year one.
- Consumption offset: the share of your modeled annual use the array may supply.
- Model inputs: address, roof planes, tilt, azimuth, shade, equipment, and system losses.
The South Carolina Energy Office explains that actual output depends on roof orientation, tilt, shading, dust, and system efficiency—not panel wattage alone. Its solar basics page is a useful reminder of why two equally sized systems can have different estimates.
Normalize the estimate with a second formula:
Year-one production in kWh ÷ system size in kW = modeled kWh per kW
This is not a pass/fail benchmark. It is a way to expose a mismatch. If three designs use similar roof planes but one promises materially more kWh per kW, ask which input creates the difference. Does it assume tree removal? A different shade reading? A more favorable roof plane? Lower system losses? The answer should be reproducible.
You can also enter the proposed size and roof assumptions into the National Renewable Energy Laboratory’s PVWatts Calculator. PVWatts estimates grid-connected PV production and is a useful independent reasonableness check, not a guarantee of what your system will produce.
Treat lifetime savings graphs cautiously. Weather varies, equipment degrades, electricity rates change, and utility compensation rules can change. A quote should make those assumptions visible instead of presenting the final savings number as certain.
Calculate price per watt the right way
Price per watt helps compare solar arrays of different sizes:
Solar-only cash price before incentives ÷ system watts DC = cash price per watt
If an array is 8 kW, use 8,000 watts in the denominator. The arithmetic is simple; choosing the right numerator is where comparisons go wrong.
Use the cash price before tax credits or rebates, not a “net cost,” loan principal, or sum that includes a battery. Separate these items first:
- solar array and standard installation;
- battery and backup equipment;
- roof work;
- main-panel, service, or other electrical upgrades;
- trenching, tree work, structural work, or special mounting;
- financing charges; and
- optional monitoring or service plans.
A battery adds cost but not solar-panel watts, so including it in the numerator makes the array’s price per watt look artificially high. The same is true of a roof replacement or major electrical upgrade. Compare those scopes in their own rows.
Price per watt is a screening tool, not a winner selector. A higher figure may reflect real scope, a difficult roof, stronger labor coverage, or necessary electrical work. A low figure may be perfectly reasonable—or may leave out permits, interconnection, critter guards, monitoring setup, or post-install labor. Ask what is included and what can trigger a change order.
For a property-specific planning baseline, use the South Carolina solar cost calculator, then compare its assumptions with the written bids. A calculator is not a substitute for a roof and electrical assessment.
Separate the cash deal from the financing deal
A low monthly payment does not tell you the system price. For every loan quote, request all of the following in writing:
- cash price for the same scope;
- financed amount or loan principal;
- down payment;
- annual percentage rate (APR), not only the note rate;
- loan term and payment schedule;
- total of all scheduled payments;
- prepayment rules and penalties, if any;
- whether the payment changes if you do not make a lump-sum prepayment; and
- every lien, UCC filing, transfer, or sale-of-home requirement.
The Consumer Financial Protection Bureau warns that some solar-specific loans build dealer fees into the loan principal, which can obscure the difference between the cash price and financed cost. The CFPB’s solar financing advisory recommends asking for the cash price, shopping among installers and lenders, and getting a written breakdown of work, materials, and costs.
Compare financing with the total dollars paid over the full term, not just APR or the first monthly payment. A long term can lower the payment while increasing total interest. A lower advertised rate can also accompany a higher financed price. If one proposal combines the installation and loan into a single number, insist on both cash and financed versions for identical equipment and scope.
If you are comparing a lease or power-purchase agreement, use a different worksheet. Record ownership, starting payment or energy rate, annual escalator, term, buyout schedule, transfer rules, removal terms, maintenance responsibility, and total projected payments. Do not compare a third-party-owned agreement with a cash purchase using price per watt as though they were the same product.
Correct outdated incentive math before comparing quotes
As of August 2026, an owner-purchased residential proposal should not subtract a new 30% federal Section 25D credit from its price. The IRS states that the Residential Clean Energy Credit is not available for property placed in service after December 31, 2025.
If a current quote still shows that federal homeowner credit, ask for corrected cash, loan, payment, and payback figures. Do not let an outdated “net price” determine which proposal wins.
South Carolina incentives have separate rules and depend on ownership, qualifying costs, state tax liability, and your facts. Compare gross prices first, review current South Carolina solar incentives, and confirm tax treatment with a qualified tax professional. An installer can identify programs but should not guarantee your tax result.
Make the utility assumptions match your address
A production estimate tells you how much electricity a system may generate. A savings estimate also needs to model what happens to that electricity: how much you use immediately, how much you export, how exports are credited, and what fixed or program charges remain.
South Carolina does not have one universal economic assumption for every address. The state Energy Office notes that the dollar value of exported solar can vary by utility and advises consumers to confirm current fees and requirements directly with their provider. Review its net-metering guidance, then compare the proposal with the site’s South Carolina utility guides and net-metering overview.
Add these questions to every quote review:
- Which utility and tariff or program did the model use?
- What export-credit value and fixed charges are assumed?
- What share of production is assumed to be used in the home versus exported?
- Does the design require a battery or load shifting to reach the modeled result?
- Who files the interconnection application, and are fees included?
- What happens if the utility requires a design change?
Do not accept a utility assignment based only on the city name. Service territories can vary, and a cooperative or municipal provider may have different rules from a nearby investor-owned utility. Verify the provider on a current electric bill.
Compare equipment as a complete system
Panel brand alone does not decide system quality. Record exact model numbers and verify how the components work together.
Panels
Compare rated watts, efficiency when roof space is constrained, product warranty, performance warranty, degradation terms, dimensions, and who handles a claim. Ask whether the quoted model can be substituted and, if so, what written approval you have.
Inverters
Record whether the design uses a string inverter, optimizers, or microinverters; the exact models; AC capacity; monitoring; warranty length; and labor coverage. Ask how shade, multiple roof planes, clipping, expansion, and replacement would be handled. A premium panel paired with an underspecified or poorly supported inverter is not a premium system.
Batteries
Compare usable energy capacity in kWh, continuous and surge power in kW, backed-up circuits, inverter integration, warranty throughput or cycles, operating mode, and whether the proposal includes a critical-loads panel or other electrical work. “Whole-home backup” is not meaningful without a load plan and power limits. Review battery storage options separately from the solar-array comparison.
For every product, identify the named warranty obligor and distinguish the manufacturer warranty from the installer’s labor obligation. If equipment fails, who diagnoses it, removes it, ships it, reinstalls it, and pays for that labor? A long product warranty can still leave a service gap.
A third quote, written properly
Two quotes that disagree? Get a tie-breaker
We will quote the same scope in a format you can put beside the others: system size in kW DC and AC, modeled production with its assumptions, cash price, equipment models, and what is excluded.
Book a free assessment See residential solar · cost calculator
Compare scope, warranties, and the company behind them
The contract should say who is responsible for design, engineering, permits, HOA documents, utility interconnection, inspections, installation, monitoring setup, activation, and closeout paperwork. On a designated property that paperwork is a different animal — see Charleston historic-district review for what a BAR submission adds to the scope. It should also list exclusions and the events that permit a price or equipment change.
South Carolina-specific due diligence matters here. The South Carolina Energy Office says residential solar work requires particular licensing or registration, with additional roofing classification for roof-mounted work. Check the state’s solar licensing requirements, then verify the legal name and current status through the South Carolina LLR license lookup. Ask who holds each required credential if sales, electrical, roofing, and installation work involve different companies.
Compare warranty promises in four separate rows:
- manufacturer product warranty;
- manufacturer performance warranty;
- installer workmanship and roof-penetration coverage; and
- production guarantee, if one is actually offered.
Read exclusions, transfer rules, claim steps, response obligations, labor coverage, and remedies—not only the headline term. A production guarantee should define the promised kWh, measurement period, exclusions, monitoring requirements, and what you receive if production falls short.
Finally, identify the contract party. Is it the salesperson, installer, dealer, lender, or another company? Ask who employs or subcontracts the installation crew and who will answer a service request years later. Reviews can help identify patterns, but written scope, verified credentials, financial terms, and enforceable warranty language should carry more weight than a star average.
Red flags that should pause the decision
Pause and get clarification when a quote has any of these problems:
- only a monthly payment, with no cash price or total payments;
- no kW DC system size or year-one kWh estimate;
- a 2026 owner-purchased price reduced by the expired federal homeowner credit;
- equipment described only as “premium” without model numbers;
- no roof layout, shade basis, or production assumptions;
- no stated utility program or export-credit assumption;
- a battery described as whole-home backup without usable capacity, output, or backed-up loads;
- vague “25-year warranty” language that does not separate product, performance, and labor;
- verbal promises missing from the contract;
- unresolved blanks for permits, interconnection, HOA, roof, or electrical work;
- pressure to sign before you can review the contract or another quote; or
- a contractor name or credential that you cannot verify in the state database.
For a covered South Carolina consumer purchase or lease, Regulation 28-78 requires a standardized disclosure and a written agreement that identifies key terms such as the total price including interest and fees, system and design assumptions, expected installer and servicer, warranties, and interconnection responsibility. When financing is offered by or through the retailer, the finance agreement must be a separate addendum and disclose the amount financed, payment schedule, and APR. The regulation also gives the consumer until midnight of the tenth calendar day after signing a compliant agreement to cancel. Compare the supplied disclosure, agreement, and any finance addendum against each other; follow the cancellation notice exactly and keep delivery evidence.
Some transactions signed at your home or away from a seller’s permanent place of business may also fall under the Federal Trade Commission’s three-business-day Cooling-Off Rule. The FTC rule summary explains the narrower federal scope. Do not assume that either rule automatically resolves every related credit agreement, deadline, or dispute. Read every cancellation section before signing and seek legal advice if your rights are unclear.
A practical way to choose the winning quote
Use this order so a persuasive payment pitch does not outrank the project itself:
- Reject incomplete bids. Require system size, production, cash price, equipment, scope, and contract terms in writing.
- Normalize the design. Confirm the same usage history, goals, and battery or roof scope.
- Investigate outliers. Ask why size, production per kW, or price per watt differs.
- Correct the economics. Use the right utility assumptions, remove unavailable incentives, and calculate total financing payments.
- Verify delivery. Check licenses, installer identity, permit and interconnection responsibility, warranties, and service process.
- Choose the best-supported fit. Favor the proposal that clearly connects design, cost, risk, and responsibility—not automatically the highest or lowest price.
Solar may not be the right project yet if the roof needs near-term replacement, the usable area is heavily shaded, the quote depends on an incentive you cannot use, financing erases the expected benefit, or no installer can explain the design credibly. Waiting, repairing the roof, reducing usage, or getting a clean rebid can be the better decision.
If you already have proposals for a residential solar installation, talk through your quotes with a local team. Sunburst can compare the underlying design, utility assumptions, scope, and financing questions with you before you decide. The goal is a quote you understand, not pressure to choose one quickly.
Where Sunburst fits your comparison
Use this article on us as well as on everyone else. Sunburst proposals state the DC and AC system size, the production model and its inputs, the cash price before any financing, the exact equipment, the electrical and roof scope, the utility interconnection and permit responsibilities, and the exclusions. We do not present guaranteed savings, and we do not discount for signing today.
Two things worth checking on every South Carolina quote, ours included: whether the production estimate matches your address and roof rather than a regional average, and whether the utility assumptions match the provider on your bill — Dominion, Duke, Santee Cooper and the cooperatives credit exports differently, and that difference outweighs small price gaps.
Read next: how to vet the companies behind the quotes, module-level comparison, payback arithmetic and what a site survey should confirm before the final price. See solar installers by city, the solar cost calculator, or book a free assessment.
Frequently asked questions
How many solar quotes should I get?
Get enough comparable written bids to identify outliers; for many homeowners, three is practical. More quotes do not help if they use different usage data or leave key fields blank. Give each installer the same 12 months of kWh use and ask for the same cash, equipment, production, and scope details.
Should I choose the lowest price per watt?
Not by itself. Use cash price per watt to normalize the solar-only portion, then compare roof and electrical complexity, equipment, warranties, labor coverage, utility assumptions, and excluded work. A lower number is valuable only when the scope and responsibilities are truly comparable.
Should a battery be included in solar price per watt?
No. Separate the battery, backup hardware, and related electrical work from the solar-array cash price. Compare the battery on usable kWh, power output, backed-up loads, warranty, integration, and installed cost.
Why do two quotes predict different solar production?
They may use different array sizes, roof planes, shade readings, weather data, loss factors, equipment, or tree-removal assumptions. Divide annual kWh by system kW, compare the model inputs, and ask each installer to explain a material difference in writing.
What if the loan quote does not show a cash price?
Request the cash price for the exact same scope before comparing. You need the cash figure and the loan’s APR, principal, term, payment schedule, and total payments to see what financing adds. A monthly payment alone is not enough.
Can I still use a 30% federal residential solar credit in 2026?
Not for a new owner-purchased residential system placed in service after December 31, 2025, according to the IRS. Ask for corrected figures if a proposal subtracts that expired homeowner credit. Confirm any other incentive with a tax professional.
How do I verify a South Carolina solar installer?
Copy the legal business name and license or registration number from the proposal. Check the required classifications on the South Carolina Energy Office’s solar licensing page, then confirm current status in the official LLR lookup. Ask who holds the electrical and roofing credentials when multiple companies are involved.
Is the quote the same as the final contract?
Not necessarily. The contract controls the project. Match its system size, equipment, price, scope, schedule, cancellation terms, change-order rules, warranties, and verbal promises against the proposal before signing. Resolve every difference in writing.
Sources and methodology
This guide was researched on August 10, 2026. It uses current official sources for South Carolina licensing and utility context, federal tax and consumer-protection rules, financing risks, and production modeling. Price examples and market-average claims were intentionally excluded because a useful quote comparison depends on property-specific scope and current bids.
- South Carolina Energy Office, A Consumer Guide to Solar for the South Carolina Homeowner — bid inclusions, permitting, and utility coordination; accessed August 10, 2026. Older incentive material was not used.
- South Carolina Energy Office, How Solar Works — system ratings and production variables; accessed August 10, 2026.
- South Carolina Energy Office, Tax Credits, Incentives, and Net Metering — utility-specific export value, fees, and verification guidance; accessed August 10, 2026.
- South Carolina Energy Office, Licenses and South Carolina LLR license lookup — required classifications and credential verification; accessed August 10, 2026.
- South Carolina Code of Regulations, Chapter 28, Regulation 28-78 and Department of Consumer Affairs summary — covered-agreement disclosures, separate finance addendum, party responsibilities, and cancellation timing; accessed August 10, 2026.
- Consumer Financial Protection Bureau, solar financing consumer advisory — cash-price comparison, dealer fees, and loan risks; page modified June 25, 2026; accessed August 10, 2026.
- Internal Revenue Service, Residential Clean Energy Credit — Section 25D end date for new residential property after 2025; page updated July 4, 2026; accessed August 10, 2026.
- NREL PVWatts Calculator — independent grid-connected PV production estimate; accessed August 10, 2026.
- Federal Trade Commission, Cooling-Off Rule — conditional cancellation right for covered off-premises sales; accessed August 10, 2026.