Solar panel types and warranties: what to buy and what to ignore

For a Florida home the short answer is: monocrystalline panels at 400 W or more, from a manufacturer likely to exist in 20 years, with a 25-year product warranty and a performance warranty around 85% at year 25. Everything else (“premium” brand, “Tier 1,” “German technology”) is sales talk, not decision criteria.

What panel types exist and which one makes sense?

Three technologies, and for a home roof only one makes sense today.

Efficiency measures how much light the panel turns into electricity per square meter. It matters for space: at 20-23% the system fits on less roof. EnergySage notes monocrystalline prices have dropped enough that the old price argument for polycrystalline no longer applies.

Within monocrystalline there are variants (PERC, TOPCon, HJT) that differ in efficiency and how they handle heat. EnergySage reports panels lose 0.3% to 0.5% of output per degree Celsius above 25 °C; newer technologies sit at the low end of that range, which is worth something in Florida. But it is a refinement, not a purchase decision.

What wattage should the panel be?

400 W or more. EnergySage reports that 97% of residential panels in 2026 fall in that range. A 400-440 W panel takes about the same space as a 350 W panel from a few years ago; it simply converts more. If a proposal shows panels well under 400 W, ask why: it may be old inventory sold at new prices.

What does “Tier 1” mean?

It means the manufacturer is financially solid according to an industry list (the most cited is BloombergNEF’s), which assesses whether banks finance large projects using their panels. It does not evaluate the quality of each panel or its durability on your roof.

Why it still matters: a manufacturer that survives can honor a 25-year warranty; one that goes bankrupt cannot. Why it is not enough: there are manufacturers off that list with good products, and manufacturers on it that have shipped problem batches. Use it as a survival filter, not a quality seal.

What are the three warranties and who provides them?

They are three separate documents with three separate responsible parties, and you want each one on its own.

1. Product warranty (manufacturer). Covers the panel not failing physically: defects, delamination, connections. EnergySage describes it as historically 10-12 years, with many manufacturers now offering 25. Ask for 25.
2. Performance or production warranty (manufacturer). Promises the panel will keep producing a minimum percentage of its rated power each year. EnergySage reports the standard is around 85% at year 25, with older warranties at 80%. A panel promising 85% at 25 years is promising roughly 0.6% degradation per year.
3. Workmanship warranty (installer). Covers the installation: leaks at roof penetrations, wiring, mounting. It comes from the installer and varies enormously. If the installer closes, this warranty vanishes with them; the two above remain with the manufacturer.

Heads up: the phrase “25-year warranty” in a proposal can refer to any of the three, or just one. An installer can say “25-year warranty” when the manufacturer gives 25 on performance but the installer gives 1 year on workmanship. Ask for all three terms separately and in writing, and ask what each covers in dollars: parts, replacement labor, shipping. Many manufacturer warranties cover the part but not the technician who climbs on the roof to swap it.

How much does a panel really degrade?

About 0.5% a year. That is the median NREL (the national renewable energy laboratory) found analyzing thousands of installed systems; panels made before 2010 degraded faster, and modern ones sit in that range or slightly better.

In practice: a system producing 15,000 kWh in year one produces about 13,200 kWh in year 25 at 0.5% degradation. That decline should be in the proposal’s simulation; if the 25-year projection shows flat production, it is inflated.

What does a panel have to meet in Florida?

Product approval for wind. Florida operates under the Florida Building Code, which adopts ASCE 7 for wind loads, and in Miami-Dade and Broward (the High Velocity Hurricane Zone, HVHZ) installed products must carry a Miami-Dade Notice of Acceptance or a state product approval (FL#). That applies to the racking and the panel. An “excellent” panel without approval for your county cannot be permitted. More in solar and hurricanes in Florida.

When it does NOT make sense

• Paying a premium for a “premium” panel when the roof has space to spare: annual production will be the same with a standard panel carrying a good warranty.
• Choosing by panel brand and neglecting the inverter: the inverter is the part that fails most (see string inverters vs microinverters).
• Accepting panels from a manufacturer you cannot find on the market today: a 25-year warranty is worth whatever the company signing it is worth.
• Buying a sub-400 W panel at 2026 prices without an explained reason.

What to check before you decide

• Ask for the exact make, model and wattage of the panels in the proposal, and look up the datasheet.
• Ask for the three warranty terms separately: product, performance and workmanship, and who is responsible for each.
• Verify the performance warranty promises close to 85% at year 25 and that the simulation includes degradation.
• Ask whether the panel and racking have product approval for your county (NOA or FL#).
• Keep the warranty sheets with your serial numbers: if the installer disappears, that is what you will need (see solar panels not producing: what to do).