Deploying solar farms is an investment in the future. The effect of considerable investments in solar farms will manifest itself in many, many years. And it’s all the more annoying that manufacturers give very overestimated estimates of the duration of the effective operation of solar panels. By and large, today’s solar panels last much faster than the claimed 25 years, a new study has shown.
Measurement of the current-voltage characteristics of a photopanel from one of the manufacturers in the study. Image Source: Energy Conversion and Management
In an article in the journal Energy Conversion and Management, a group of scientists from Ghana examined 48 solar panels from 12 manufacturers. Photo panels were selected 4 pieces from each brand by stratified random sampling from farms that have worked in the same conditions from 5 to 9 years, even without partial shading. All panels, to clarify, are mass-produced low-cost solar cells made of polycrystalline silicon. More expensive photopanels made of single-crystal silicon will probably have better results, but due to the rarity of use, they cannot yet form statistics. It should also be taken into account that in Ghana, where the degradation rate of polycrystalline photo panels was tested, the climate is hot and at the same time humid, which could affect the reduction in the life of solar panels.
In general, it turned out that photo panels from 11 manufacturers degraded so quickly that they would fail before 20 years of operation, not to mention the promised 25 years of guaranteed operation. The photopanels of the 12th manufacturer generally degraded in accordance with the declared characteristics and can be considered reliable, although the researchers cannot state the characteristics of other batches of photopanels from this production. Therefore, in particular, the names of photopanel manufacturing companies are kept secret. Without a global study, it would be reckless to scold some and praise others.
Samples of photopanels with power from 100 to 460 W participated in the study. First, the samples were first visually inspected according to a methodology developed by the US Department of Energy’s National Renewable Energy Laboratory (NREL). After that, each panel was tested in operation using the Seaward PV210 tester.
Testing showed that the minimum degradation rate of the analyzed modules was 0.79% per year, and the maximum was 1.67% per year. The rate of degradation of modules was different: in the range of 0.78–1.95% per year with an average and median rate of degradation of 1.36% per year and 1.38% per year.
Photopanels from only one manufacturer degraded by less than 0.8% per year, while modules from other manufacturers degraded by more than 1.0% per year. This means that the panels can fail much earlier than 20 years of operation. Six of the 48 modules are likely to last more than 20 years, and only four are 25 years declared by the manufacturer. At the same time, scientists noted that the rate of degradation did not depend on the age of the modules. Both “younger” panels and more “old” ones degraded equally quickly.
In their article, the scientists emphasized that, according to the data they have, a similar rate of degradation of polycrystalline solar panels has been noticed by researchers in other countries. It would be nice to clarify this issue.
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