Managers of large solar power plants around the world are sounding the alarm. There have been many reports of cases of photo panels being damaged for no apparent reason.. An analysis of the situation without delay showed that this may be due to changed panel production technologies, which was not fully taken into account during testing of finished products in production.
Image source: PVEL
“We've seen reports of glass [on panels] breaking for no apparent reason coming from Brazil, Chile, Australia, the United States and other countries, ” said Tristan Erion-Lorico, vice president of sales and marketing for the testing lab. solar equipment PVEL. — It did not depend on the region, type of system and manufacturer. That's why it's so concerning.”
There are no accurate statistics on damage to panels on projects. According to PVEL, we are talking about hundreds of MW of installed capacity. Some cases were investigated in detail and even explanations were found for the damage, in particular, the fact that the glass covering was damaged by overly powerful robotic lawn mowers that threw stones at the panels was proven, but in most cases the reasons were never identified.
Separately, power plant operators emphasize that the damaged photo panels were not exposed to strong winds, rain or hail. It’s just that during the next inspection, new cracks were suddenly discovered in the glass coating of the panels, which were not there during previous inspections.
An early analysis of cases of cracking of protective glass of photopanels showed that in many cases a certain pattern can be traced. All of them refer to photopanels with two protective glasses – one on each side of the solar module. Previously, photo panels were covered with only one 3.2 mm protective tempered glass on the top side of the module, while the back of the module was covered with a plastic base. About 10 years ago, companies launched the production of photo panels with protective glass on both sides of the module, which was supposed to increase their resistance to the external environment and loads. However, in order to reduce the weight of the modules, the thickness of the protective tempered glass had to be reduced to 2 mm, which ultimately increased the likelihood of damage.
The caveat is that panels with two glasses are tested to meet industry standards, but, of course, not every panel released. Moreover, the standard allows changing the supplier of protective glass without additional certification.. For 3.2mm glass this didn't make much of a difference, but for thinner glass it seemed like I had to be more selective in my choice of materials.
Experts also note that glass tempering technology provides different quality depending on its thickness and additives.. For example, the glass must be relatively thick so that the heating of the inside is at a given level. It is easier to withstand these conditions for thick glass than for thin glass.. Ultimately it's a matter of manufacturing costs. If there is an opportunity to save money, then take advantage of it.
Finally, reducing the thickness of the glass made it possible to lighten the frame of the modules, which increased the load directly on the glass. The same applies to the methods used for attaching (clamping) photo panels to systems for adjusting the angle of incidence of lighting and simply to stationary stands. Panel manufacturers, for their part, take these points into account (but not all), and issue recommendations on fastening methods and permissible loads, but there is no uniform methodology or standard. Therefore, there is a growing need in the industry to revise a number of standards, for example, for testing panels by manufacturers and carrying out new certification.
In the USA, the National Renewable Energy Laboratory (NREL) took on the problem.. Researchers began to study cases of damage to photo panels by analyzing glass, their structure, quality, chemical composition and physical properties. Special equipment is being used and scientific methods are being developed, which promises to help develop new standards for testing the quality of photo panels and their ability to withstand mechanical stress.
“Products are changing faster and it's harder to stay ahead of the curve, ” said Ingrid Repins, senior scientist in NREL's Photovoltaic Reliability Group.. “These cracked glasses took us by surprise, although I think we knew to some extent that there were weaknesses and gaps in the testing methods.”. We will now try to understand the root cause and develop tests to ensure this doesn't happen again.. At this point, we have research and we have questions, but we don’t have answers yet.”