Is your roof ready for solar? Check it by address
Solar panels last about 25 years. If the roof under them won't, you pay to take the panels off and put them back. This check reads your roof's outline from your address, works out which sides face the sun, and compares the roof's remaining life with the panels'.
1. Find your house
2. Your solar readiness
Example result: a 60 × 30 ft ranch near Phoenix, AZ, long side facing south, 6/12 gable, 12-year-old architectural shingles. Look up your address to replace it with your house.
- Verdict
- Replace the roof first, or together with solar
- Usable panels
- 28 panels · 11.2 kW at 400 W each
- Yearly output
- 19,958 kWh a year (PVWatts)
- If panels must come off later
- $5,600 – $8,400 to remove and reinstall
3. Your roof details
How the check works
- Roof outline. We fit a rectangle to your building's OpenStreetMap outline and put the ridge along the long side. A gable roof has two planes facing away from the ridge. A hip roof adds two small end planes.
- Sun by direction. Each plane gets the share of a south-facing array's yearly output that NREL's PVWatts model gives for that direction and pitch. Planes under 75% are skipped.
- Panels. The usable share of each sunny plane, divided by about 21.5 sq ft per panel.
- Yearly kWh. Panels × panel watts × the PVWatts yield of the nearest reference city × the direction factor.
- Roof life. Typical life for your material minus its age, compared with a 25-year panel life.
| Roof faces | 6/12 roof |
|---|---|
| South | 100% |
| Southeast / southwest | 94% |
| East / west | 81% |
| Northeast / northwest | 65% |
| North | 58% |
| Reference city | kWh per year per kW of panels |
|---|---|
| Phoenix, AZ | 1,782 |
| Los Angeles, CA | 1,701 |
| Denver, CO | 1,634 |
| Dallas, TX | 1,523 |
| Seattle, WA | 1,109 |
Worked example
A 60 × 30 ft ranch with its long side facing south, a 6/12 gable roof and 12-year-old architectural shingles, near Phoenix, AZ. The south plane is about 1,006 sq ft. At 60% usable that fits 28 panels, or 11.2 kW, and about 19,958 kWh a year. The north plane is skipped at 58%. Architectural shingles last about 20–30 years, so this roof has roughly 8–18 left, which is less than the panels' 25. Removing and reinstalling 28 panels later would cost about $5,600–$8,400. That's why the verdict is to re-roof first.
Re-roof first, or put panels on now?
| Roof situation | What usually makes sense |
|---|---|
| Asphalt roof under 10 years old, no leaks | Install solar now. The roof will likely last most of the panels' life |
| Asphalt roof over 10 years old | Get a roof quote alongside the solar quote. Re-roofing first avoids a later $200–$300-per-panel removal |
| Metal, tile or slate in good shape | Usually ready. Ask the installer about the right mounts for your material |
| Any roof with leaks, soft spots or a sagging ridge | Repair or replace before anything is mounted on it |
Pricing a new roof first? Use the roof estimate by address for a size-based range, then the quote comparer once bids come in.
Sources
NREL (now NLR) PVWatts v8 calculator API, fetched 2026-11-09: fixed roof mount, standard modules, 14% system losses. Tilt equals roof pitch (PVWatts tilt help: 4/12 = 18.4°, 6/12 = 26.6°, 8/12 = 33.7°).
EnergySage, Do you need a roof replacement with solar panels? (updated May 15, 2026): about $200–$300 per panel to remove and reinstall, $1,500–$6,000 for most systems, and the over-10-years asphalt rule.
Planning estimate only. It does not account for shade, local fire-code setbacks, structural capacity, utility rules or incentives. A solar installer's site survey decides the real layout.
Frequently asked questions
Should I replace my roof before installing solar panels?
Often yes, if the roof is asphalt and more than about 10 years old. Panels last about 25 years, and removing and reinstalling them for a later re-roof costs about $200–$300 per panel (EnergySage).
How much does it cost to remove solar panels to replace a roof?
About $200–$300 per panel to remove and reinstall, or roughly $1,500–$6,000 for most home systems, plus the roof itself.
Is an east- or west-facing roof good for solar?
Yes, usually. In NREL PVWatts runs for a 6/12 roof in Kansas City, east or west planes produce about 81% of a south-facing array. North-facing planes produce about 58%, and this check skips them.
How many solar panels fit on my roof?
Take the area of each sunny side, keep about 60% for setbacks and vents, and divide by about 21.5 sq ft per panel. The check does this from your address outline.
Does this tool replace a solar quote?
No. It is a planning check. It cannot see shade, vents or local fire-code rules, and it does not price the solar system.