Types of solar panel compared

Solar panels fall into a few groups. The differences come down to how the silicon is made, which sets how much power a panel produces for its size. Here is how they compare:

Efficiency is the share of sunlight a panel turns into electricity. A higher number means more power from the same area. That sounds like it should settle the choice, but on most roofs the gap between good panels is small. On a normal roof, the efficiency figure is mostly marketing.

The reason is space. If your roof has plenty of room, you can fit enough standard panels to reach the system size you need, and the extra point or two of efficiency from a premium panel buys you very little. A standard panel and a premium one of the same physical size differ by perhaps 30 to 50 watts. Across a ten-panel array that is a few hundred watts, which a roof with spare space can simply make up with one more panel at a fraction of the price premium.

Where higher efficiency does earn its keep is a small or awkward roof, where you need to squeeze the most power into a limited area. A short roof slope, dormers, chimneys and rooflights all eat into the usable space. On a roof that can only physically hold eight panels, a higher-efficiency panel that makes 440 watts instead of 400 adds up to a meaningful difference, because there is no room for an extra panel to close the gap. There it can be the difference between hitting your target system size and falling short.

For a typical roof, the panel type is rarely the thing that decides how well a system performs. Three things tell you more, and they are worth checking on any quote.

The warranty comes in two parts. The product warranty covers materials and workmanship, usually 15 to 25 years. The performance warranty, or degradation guarantee, promises a minimum output at year 25, often at least 80 to 85 percent of the original. That second figure is the one to compare, because it tells you what the maker expects the panels to still be doing after a quarter of a century. Good panels lose only about half a percent a year, so they should track close to that curve.

The installer and the system design matter just as much. The wiring, the inverter and how the panels are laid out around shading, chimneys and roof angles all shape the real-world output far more than a point of panel efficiency. A panel in partial shade for part of the day, or wired into a string that drags the others down, will under-perform whatever its rating. A well-designed system with mainstream panels will out-perform a poorly designed one with premium panels. Spend the attention there. Chasing the highest efficiency figure while ignoring the warranty and the install is the wrong order.

For almost every UK home in 2026, mainstream monocrystalline panels are the sensible choice. They are the standard for good reasons. Strong efficiency, long warranties, low degradation and a proven track record. Reach for high-efficiency N-type panels only when your roof is genuinely short of space.

Polycrystalline panels are worth knowing about mainly so you can spot them in an old quote or a second-hand system, where their lower output and larger footprint count against them. Thin-film is for special cases, not normal tiled or slate roofs. The work itself is carried out by MCS-certified installers, the standard required for export payments and most grants, which is a better guide to a good outcome than the panel brand alone.