Solar panels, honestly explained

Panel wattage and efficiency

Residential panels today typically range from 400W to 450W per module, with efficiency ratings around 20–22%. Higher-wattage panels let you fit more capacity on the same roof, which matters when roof space is limited by dormers, chimneys, vents, or HOA aesthetic requirements. Efficiency differences of a few percentage points rarely change the financial picture as much as system size and shading do — a slightly less efficient panel on an unshaded rear roof usually beats a premium panel on a partially shaded roof.

Degradation

Solar panels lose a small amount of output each year — typically about 0.4–0.6% annually for premium panels, and up to 0.8% for budget panels. A 25-year performance warranty commonly guarantees the panel produces at least 85–92% of its original nameplate output at year 25. Real-world Colorado systems installed in the mid-2010s are generally tracking better than their warranted degradation curves.

Warranties

• Product warranty: covers manufacturing defects, typically 12–25 years.
• Performance warranty: guarantees minimum output over time, typically 25 years.
• Workmanship warranty: covers the installer's labor and roof penetrations. Varies widely (5–25 years) and is often the most meaningful warranty in practice, because it is the one you will actually call.
• Inverter warranty: typically 10 years for string inverters, 25 years for microinverters.

Hail testing

Certified panels pass an impact test with a 1-inch (25 mm) ice ball at ~50 mph under UL 61730 and IEC 61215. Colorado hailstorms regularly produce larger stones — 2 to 3 inches, occasionally larger. Several manufacturers now offer enhanced hail testing at 2- or even 3-inch impact ratings. In practice, what matters most for hail resilience is:

• Panel glass thickness (3.2 mm tempered glass is standard; some premium panels use 4 mm).
• The mounting angle (steeper tilt tends to deflect impacts).
• How your installer handles a hail claim — inspection, insurance filing, and remove-and-reinstall.

Panel placement

South-facing roof surfaces produce the most energy in Colorado, but east and west facings are viable — especially with time-of-use rate plans that reward late-afternoon production. North-facing slopes are generally not usable. Shading from trees, chimneys, vent stacks, and neighboring structures reduces output significantly, and a single shaded panel can drag down an entire string inverter's output if microinverters or optimizers are not used. Placing panels on the rear (back-side) roof plane keeps the street-facing view of your home clean and is often preferred by HOAs — most Front Range communities explicitly require this when the rear plane has sufficient sun exposure.

Inverter selection

Three architectures are common in Colorado residential systems: a single string inverter (cheapest, worst shading tolerance), power optimizers with a central inverter (middle ground), and microinverters (one per panel, best shading tolerance and per-panel monitoring, most expensive). For most Colorado homes with any tree cover or roof complexity, microinverters or optimizers are worth the premium.