How long do solar panels last? Lifespan and degradation
Solar panels are designed to last about 30 years and lose around 0.5% of their power a year. We explain what speeds up wear and how to extend their lifespan.
Quick summary
- The reference lifespan of a solar panel is about 30 years [1].
- An NREL analysis of nearly 2,000 measurements puts median degradation at 0.5% a year [2]; the average is somewhat higher, around 0.8% [3].
- At 0.5% a year, after 25 years a panel would keep about 87% of its initial power.
- Hot spots, micro-cracks and aggressive cleaning can speed up wear.
Solar panels don't suddenly "break down" like an appliance: they gradually lose power. That is why we talk about two different things: lifespan (how many years they keep working) and degradation (how much power they lose each year).
How many years do they last?
The International Renewable Energy Agency (IRENA) and the International Energy Agency's photovoltaic programme use a lifespan of about 30 years as a reference in their report on end-of-life panels [1]. Many installations keep producing beyond that, although at lower power.
How much power do they lose each year?
The benchmark study is by Dirk Jordan and Sarah Kurtz of the US National Renewable Energy Laboratory (NREL), who compiled nearly 2,000 degradation rates measured on real modules and systems. The median was 0.5% a year [2]. A later presentation from the same laboratory shows the average at around 0.8%, because some installations degrade much faster than most [3].
| Years | At 0.5% a year | At 0.8% a year |
|---|---|---|
| 10 | 95% | 92% |
| 20 | 90% | 84% |
| 25 | 87.5% | 80% |
| 30 | 85% | 76% |
A linear calculation using the reference rates. Check your manufacturer's power warranty: it usually states the minimum percentage guaranteed at 25 or 30 years.
Regular cleaning and inspection helps your panels reach 30 years in good shape.
Online quote calculatorWhat speeds up wear
- Hot spots from shading or localised dirt: the covered cell heats up and can be damaged [4].
- Mechanical loads: stepping on modules or resting tools on them. Manufacturers limit the load allowed during cleaning [5].
- Aggressive cleaning: excessive pressure, chemicals or hard brushes that scratch the glass or its anti-reflective coating [5].
- Moisture and connections: pressurised water aimed at the junction box or connectors [5].
How to extend your panels' life
- Clean them with purified water at low pressure, without walking on them.
- Remove droppings and localised dirt before they cause hot spots.
- Inspect modules, fixings and wiring regularly.
- Monitor production to catch an abnormal drop in time.
At TARRAMED, a solar panel cleaning company in Tarragona, we combine cleaning with a visual inspection of the installation and a photo report, so your panels reach 30 years in the best possible condition.
About the sources: the water quality, pressure and temperature figures in this article come from the cleaning guidelines of First Solar, one of the largest US manufacturers of solar modules, which makes thin-film modules; silicon modules, more common on rooftops, may have slightly different specifications. Each manufacturer publishes its own, which is why at TARRAMED we always follow those of your panels' manufacturer.
Want us to take care of it?
At TARRAMED we combine cleaning with purified water, visual inspection of modules, fixings and wiring, and bird-proofing with mesh, so your installation stays in good condition throughout its working life.
TARRAMED, cleaning company in Tarragona
We are a cleaning company in Tarragona specialising in solar panel cleaning, industrial cleaning and technical and high-access cleaning. We work in Tarragona, Reus, Valls, Salou, Cambrils, El Vendrell and the whole Camp de Tarragona area, and travel to Barcelona, Lleida and Girona, as well as Aragon and Biscay. We clean with purified water, with a fixed quote, a photo report and a written guarantee.
References
- IRENA and IEA-PVPS (2016). End-of-Life Management: Solar Photovoltaic Panels. irena.org
- Jordan, D. C. and Kurtz, S. R. (2013). Photovoltaic Degradation Rates – An Analytical Review. Progress in Photovoltaics, 21(1), 12-29. NREL/JA-5200-51664. osti.gov
- Jordan, D. C. (2015). PV Degradation Rates, NREL presentation. nrel.gov
- Dolara, A., Lazaroiu, G. C. and Leva, S. (2016). Hot-spot phenomenon in PV systems with overhead lines partial shading. U.P.B. Scientific Bulletin, Series C, 78(4). re.public.polimi.it
- First Solar (2017). PV Module Cleaning Guidelines, PD-5-804 Rev 3.4. firstsolar.com
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