How to compare solar quotes

Price per watt creates a useful starting point

For a purchased system, divide the cash contract price by the system’s direct-current nameplate capacity in watts. This gives a price per watt that lets you compare systems of different sizes. Use the price before incentives unless you apply exactly the same confirmed incentives to every quote. Keep batteries, roof replacement, main-panel upgrades, trenching, and other major extras separate so they do not distort the solar comparison.

Price per watt is a screening tool, not a verdict. A quote can cost more because it includes difficult electrical work, better roof protection, a battery, or a genuinely broader scope. It can also cost more because of sales commissions or financing charges. The number tells you where to ask questions.

An itemized quote exposes missing work

A usable proposal should make the physical system and the contractor’s obligations identifiable. At minimum, ask for:

• Panel, inverter, battery, racking, and monitoring model numbers and quantities.
• System size, roof layout, attachment method, and relevant electrical work.
• Permitting, engineering, interconnection, inspections, commissioning, and cleanup responsibilities.
• Any roof work, trenching, service upgrade, tree work, or other exclusion.
• Payment milestones, change-order terms, cancellation terms, and the expected basis for schedule changes.

The point of the list is to prevent a major task from appearing later as an expensive surprise. If one quote includes a service-panel upgrade and another says only “standard installation,” the headline totals do not yet describe the same job.

Get rules for substitutions in writing. Supply changes happen, but the installer should not be free to replace specified equipment with a materially different product without disclosure and approval. The quote should also identify the legal contracting entity and the entity that will perform the installation.

Equipment and workmanship warranties cover different failures

Manufacturer warranties generally address qualifying defects or performance conditions in the equipment. The installer’s workmanship warranty addresses installation work, subject to its written exclusions. These are separate promises from separate parties.

Read what the equipment warranty actually provides. A replacement part may be covered while diagnosis, shipping, removal, roof access, and reinstallation are not. Ask who will make the manufacturer claim and who pays the labor. For a battery or inverter, understand whether coverage changes over time or depends on operating conditions.

Read the workmanship warranty with the roof in mind. It should explain the covered work, term, exclusions, notification process, and remedy. A long term is not useful if the responsible company cannot be identified or if broad exclusions remove the failures you care about.

The warranty is only as durable as its underwriter

“Warranty included” is incomplete. Identify who legally issues each warranty. It may be the equipment manufacturer, the local installer, a national sales company, a third-party administrator, or an insurer. These arrangements are not interchangeable.

Ask for the full warranty documents before signing, not a summary slide. Confirm the company names and contact process. If a third party is said to back the workmanship warranty, obtain the actual agreement and understand its eligibility requirements, exclusions, and status if the installer closes. Marketing language about protection does not create coverage that is absent from the contract.

Company age also deserves attention. A solar warranty commonly runs twenty to twenty-five years, often longer than the operating history of the contractor offering it. No quote can eliminate that risk. Clear backing, transferable terms, accessible records, and replaceable equipment can make future service less dependent on one business surviving unchanged.

Financing can hide a markup in the contract price

Do not compare a financed monthly payment with another quote’s cash total. Ask each installer for the cash price and the financed price for the same system and scope. A loan presented with an attractive interest rate may require a higher contract price. That difference is part of the financing cost even when it is not labeled as interest.

Compare total payments, term, rate, fees, prepayment rules, security interests, and what happens if the project is canceled or delayed. Consider tax incentives separately and confirm eligibility with an appropriate tax professional. A proposal that assumes you will use an incentive to make a large early payment should state what happens if you cannot or do not make it.

Leases and power purchase agreements require a different comparison because you are buying a contract for energy or equipment use rather than purchasing the system outright. Review escalators, transfer terms, maintenance duties, end-of-term options, and home-sale consequences. Do not force these offers into a cash price-per-watt comparison without accounting for the different ownership structure.

The cheapest disappearing contractor is the expensive choice

The lowest bid can be legitimate. It can also omit necessary work, rely on aggressive change orders, use an unknown subcontractor, or leave no practical service capacity after installation. A small upfront saving disappears quickly if you must hire another contractor to diagnose faults, repair roof penetrations, correct failed inspections, or complete abandoned paperwork.

Review the installing entity’s local track record and recent customer activity. Solar Installer Guild displays Google review distributions, the latest review date, and comparison with the local median. It does not verify contractors, licences, or workmanship. Check the legal company’s licence yourself through the relevant state board and confirm the name matches your contract.

The best comparison is a normalized one: same ownership type, same system scope, separate add-ons, cash and financing clearly distinguished, and written warranty responsibility. Once the quotes describe the same thing, price becomes meaningful. Until then, the cheapest number may simply be the proposal that has left the most out.