The facts about Solar PV
“The risky life of a solar PV module ”
ORAVIA has screened approximately 150 manufacturers of Solar PV modules across the world. These results have highlighted a real danger of imperfection on the modules that can lead to a decrease in the expected yield or more serious malfunctions .
A solar PV module looks falsely robust, like a glass plate in an
aluminium frame. What is more reliable at first sight?
It is a high-tech product despite its rustic appearance evolving in harsh and stressful environment.
- We expect that solar PV module provide good and loyal services for more 25 years, whereas the required life span of almost all electronic products of the market is only 5 years.
- Its heart is made of Si cells having no protection, whereas all other semi-conductors are protected in a box.
- It must be able to run normally with extreme temperatures, from Scandinavian winter to African summer.
- Si cells must provide a lot of power (more than 800 W for 100 W useful) without any cooling system, whereas normally any power semi-conductor has a radiator.
- It must bear 9 000 day/night alternations (during 25 years), with important temperature differences.
- Its big surface leads to dilatation constraints of several mm at each temperature cycle.
- It must support all external attacks without faint: rain, snow, hail, abrasive particles, sea spray, mould, droppings, acid rains, infrared/ultraviolet rays, ammoniac (agricultural sector), impacts and corrosion.
- Despite all this, it must keep its transparency to ensure a good efficiency.
This slave treatment, born during several years without any interruption, weakens the product reliability and leads to numerous breakdowns and dysfunctions.
Here are some events which can damage the « good health » of a solar PV module:
- Damaging of electrical contacts on cells
- Short-circuit at the cell level
- Cracks of Si wafer (dilatation constraints)
- Unsticking of protection layers
- Damaging of one or several by-pass diodes
- Yellowing or burnishing of coating material (EVA or others)
- Damaging of anti-reflexion treatment
- Humidity or mould
- Electro-chemical corrosion
- Overheat (bad cooling process)
- Straining of protection glass (dilatation constraints following a bad assembly)
- Damaging of electrical contacts by corrosion...
Every new model must pass specific tests to meet industry requirements, and especially tests of accelerated ageing. These ageing tests are done on a limited length and don’t show some incidents which occur in the long run.
The profession lacks the necessary perspective to interpret the results of these tests:
The records made today on ten or fifteen years old installations have little value because the technology and materials have changed considerably since then, and continue to do so. The effective lifespan of a product depends on the quality of the components used, their storage conditions, the industrial process and how they are installed. These settings are not in the instructions.
On the other hand, what is the value of the warranty offered by a manufacturer in ten years?
Some manufacturers have taken into account the lifespan problem by offering a warranty covered by a major independent insurance company. If the manufacturer disappears, the warranty remains valid throughout the duration of the contract? All manufacturers should subscribe to supplementary insurance with international companies on a product warranty and loss of yields announced.
It is essential to take into account a certain number of parameters that can secure the quality of photovoltaic panels, whatever the size of photovoltaic power plant on ground or roof:
- Storage conditions
- Assembly of components
- Calibration of machines and respect of lamination cycle
- Electric part including different welds and their temperatures
- Transport conditions
- Quality control during and after production
- Installation and connection
- Standards and certifications
To a large area integrated on the roof, the temperature of the cells at the middle of the area can reach 90 ° C in summer and without wind. This will greatly affect the cell efficiency.
More from the tester's own website http://www.oravia-energy.com/en/context.cfm