United States

Roof-mounted solar

NREL's standard benchmark models a fixed-tilt, roof-mounted residential system. Sourced facts on configuration, degradation, and service life.

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Is roof-mounted the standard residential configuration?

Yes, in the sourced modeling — NREL's 2024 Annual Technology Baseline models residential PV as "fixed tilt, roof-mounted," with a 1.21 DC-to-AC ratio, as its representative configuration. That's the baseline the sourced degradation, cost and production figures elsewhere on this site are generally built around.

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How long does a roof-mounted system actually last?

20-25 years is the sourced typical service life for the panels themselves, per DOE's consumer guidance. Inverters run shorter — string inverters typically need replacement in 10-15 years, while microinverters are expected to last closer to the panels' own lifespan. The performance warranty backing the panels typically guarantees 80% of original output at year 25.

Does my roof's condition matter before installing?

This brief doesn't have a sourced figure for roof-replacement or reinstallation cost, and that gap is explicitly noted as unresolved — the mechanism is real (a system installed on a roof nearing the end of its own service life may need removal and reinstallation when the roof is eventually replaced), but no national cost figure for that scenario is sourced here.

Does a roof-mounted system need extra structural consideration?

This brief doesn't have sourced guidance on roof load calculations or structural requirements specifically. That's a legitimate, practical question to raise directly with an installer or a structural professional, since it isn't covered in the national cost and performance research behind this site.

Sources

3 cited

Roof-mounted, fixed-tilt modeling assumption: NREL 2024 Annual Technology Baseline, Residential PV (checked 2026-08-18).
Service life figures: US DOE, A Consumer's Guide to Buying a House with Solar Panels (checked 2026-08-18).
Performance warranty: NREL/TP-7A40-73822, December 2018 (checked 2026-08-18).

How it works

From “is it worth it?” to a number you can check

Start with your power bill

The kilowatt-hours you used over the last year is the number every honest quote is built from. Without it, any price is a guess.

See what the roof can actually make

Pitch, orientation and shade decide how much of that usage a system can realistically cover. This is the step door-to-door pitches skip.

Put the quotes on one basis

Cash, loan and lease are three different products. Compare system size and total price first, then compare the financing separately.

Matched with a licensed local company

The work is done by licensed local solar companies. We do not sell panels and we do not fit them.

How we work

What to expect from this site

Every figure here carries its source and the date it was checked.

Answer first, then the working

Each page opens by answering its own question in a couple of sentences, then shows the arithmetic underneath for anyone who wants to check it.

Ranges, not one confident number

Solar pricing moves with the roof, the state, the utility and the financing. A single national figure fits almost nobody, so we publish the spread our sources support.

We say when the maths does not work

A shaded roof on a low tariff can be a poor buy. That is a legitimate answer to the question and you will find it here rather than a reason to keep reading.

We are not the contractor

We do not sell panels and we do not fit them, so nothing here depends on you signing. Licensed local companies do the work.

Questions

Frequently asked

The questions homeowners actually ask before they sign anything.

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Is roof-mounted better than a ground-mounted system?

This brief doesn't have a sourced comparison between the two configurations — roof-mounted is simply what the standard national cost and production benchmarks model as representative for residential systems.

What happens if my roof needs replacing after solar is installed?

This brief doesn't have a sourced cost figure for roof replacement or panel removal/reinstallation — it's a real, documented gap in the current research, not an answer we're withholding.

How long will roof-mounted panels actually last?

20-25 years is the sourced typical panel service life, backed by a performance warranty guaranteeing 80% of original output at year 25 in the standard case.

Does roof angle affect production the way tilt angle does in the models?

Array tilt angle is one of the six required inputs to the standard PVWatts production estimate, so yes, it factors into any sourced production figure — but this brief doesn't have a sourced rule of thumb for optimal angle by location.

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