Solar panels
Cells, glass, frame and wiring, engineered to make electricity for twenty-five years or more.
What is inside a panel
A solar panel, or module, is a sandwich: tempered glass on the front, solar cells in the middle, an encapsulating layer that seals them, and a backsheet or second glass layer behind. An aluminium frame adds strength and a junction box on the back connects the panel to the system.
Types of panel
Monocrystalline panels use cells cut from a single silicon crystal and are now the most common choice. Polycrystalline panels, made from melted silicon fragments, are cheaper but less efficient and are being phased out. Thin-film panels use very thin layers of other materials and are mostly found in large solar farms.
How long panels last
Panels have no moving parts and usually carry performance warranties of 25 to 30 years. Output falls slowly over time, typically by around half a percent a year, so a well-made panel still produces most of its original power after decades.
Advantages and limitations
Advantages
- Long life with very little maintenance
- Modular: systems can be any size
- Prices have fallen dramatically over the past decade
Limitations
- Output depends on sunlight and drops in shade
- Heat reduces efficiency
- End-of-life recycling is still scaling up
Current development
Panels keep getting larger and more efficient, and glass-glass bifacial designs are increasingly common. Recycling programmes that recover glass, aluminium, silver and silicon are expanding as early installations reach retirement.
Further reading
- Solar panel (Wikipedia)Construction, types and performance