As solar technology matures, solar cells are being produced to last longer. Therefore, production year may directly affect the lifespan of your solar panel. The EU energy institute suggests that the large majority of solar panels produced in the last 10 years will have about a 30-year lifespan, as opposed to the 20-year lifespan previously estimated. New panels may reach up to 40 years of life.
As with any product, production quality directly effects performance. A cheaper, lower-quality panel will generally have a shorter lifespan. Certain organizations, such as Underwriters Laboratories and the Solar Rating and Certification Corp., certify and rate various solar panels. A higher rating will generally indicate a longer lifespan, though specific lifespan estimates may be available from these organizations or the manufacturer.
Solar panels degenerate slowly with exposure to sunlight. A solar panel set in direct sunlight will produce a lower output than a solar panel that has spent some time in storage or in low-light areas. While there is no specific data covering various exposure figures, you can expect a panel with high exposure to fall slightly short of the 30-year lifespan mark. It is worth noting, however, that researchers test panels by subjecting them to accelerated aging with conditions closely matching those found in real-life situations.
While lifespan is certainly an important figure in determining the cost-effectiveness of your solar panel, another important figure is dollars-per-watt, or the total cost divided by the estimated wattage output. Newer panels are manufactured to produce higher outputs with smaller surface areas, but if you have ample space, an older or used panel may actually cost less for the same amount of wattage. This figure should be combined with lifespan estimates to determine the most cost-effective panel for your needs.