Solar Panels

Match wattage class to the project. Budget builds, RVs, and off-grid: 300-399W. Standard residential rooftops: 400-459W (the industry sweet spot). Premium residential and small commercial: 460-549W. Ground mounts and commercial roofs: 550-709W. The right answer maximizes watts per square foot of usable mounting area, not watts per panel.

Monocrystalline PERC is today's value standard at ~21% efficiency. TOPCon N-type adds efficiency and degrades more slowly (about 0.4%/year vs 0.55%). Bifacial glass-glass modules harvest reflected light on the rear side for 5-15% extra yield on ground mounts — but gain almost nothing on a flush rooftop. Buy TOPCon for the warranty curve, bifacial for ground mounts, PERC for the price.

Single panels and small lots ship by the most economical carrier for their size; pallet quantities (typically 31-36 panels) ship LTL freight with curbside delivery. Panels are glass — we palletize and corner-protect every shipment, and we recommend inspecting at delivery and noting any damage on the freight receipt before signing.

Two warranties matter: product (defects) and performance (output). Product warranties run 12-25 years depending on brand — Silfab and REC sit at the long end. Performance warranties are linear 25-30 year guarantees, typically promising 84-87% of rated output at the end of term on N-type modules.

Grid-tied systems require a building/electrical permit from your AHJ and an interconnection agreement with your utility before energizing — plan on both. Off-grid systems generally skip the utility but still need electrical permits in most jurisdictions. Panels themselves carry the UL 61730 listing inspectors look for.

Usually, yes — pallet per-panel pricing plus one freight charge often beats small-quantity pricing plus parcel shipping, and spare panels are cheap insurance against breakage or future expansion. Contractors buying for multiple jobs should ask about multi-pallet and truckload quotes.