301 Moved Permanently
The solar manufacturing industry is maturing, and with maturity comes increased competition. Solar module manufacturers are re-doubling their efforts to produce less expensive, more efficient solar modules to ride out the current industry doldrums and increase market share during the inevitable rebound.
At the same time they cut costs, module manufacturers cannot compromise quality. Solar modules have a long operating life, and solar photovoltaic manufacturers are beginning to warranty their products for up to 25 years because buyers want protection against defective modules.
These are the market dynamics challenging module manufacturers to deliver better designs at lower costs in less time. These efforts include looking for the lowest-cost providers of key materials like backsheets, frontsheets, glass and adhesives.
Switching suppliers in search of better deals is a routine cost-control measure in most industries. Quality does not usually enter into the thought process because it is assumed. Most industries have created systems to protect manufacturers from inferior quality. There are standards bodies policing product quality, and most suppliers have been around long enough to build up reputations that help guide buying decisions.
Solar is different. Although they have few parts relative to other complex products, solar modules are built from sophisticated materials that can vary widely in quality. The solar sector is still maturing, so there has been no industry-wide alignment of testing methods to ensure manufacturers are using comparable tests that enable buyers to make meaningful comparisons between competing products.
Variation in quality and performance standards in solar module manufacturing is a growing issue. With longer warranties comes the risk of losses from premature module failures caused by low-quality materials - backsheets that de-laminate, for example, thus eroding performance and raising the prospect of early replacement. Manufacturers are using different testing methods to make the same claims about their modules’ quality.
For example, one backsheet manufacturer might use the Society of Automotive Engineers’ (SAE) test methodology to conclude that its backsheets’ layers will stay adhered for at least 20 years. A second manufacturer might use a less stringent test that determines its layers will also adhere for 20 years.
Both manufacturers make the same claim to prospective customers. The second manufacturer can sell its backsheets for less because the company incurred lower quality-control costs.
What is a buyer to do? Because solar is a young industry, buyers lack a frame of reference for weighing the two vendors’ claims. Often, their only option is to have the competing products tested at their own expense, which defeats the purpose of seeking a low-cost supplier.
Manufacturers will be subject to UL audits to confirm they are complying with testing requirements.
Quality groundswell
The International Electrotechnical Commission (IEC) and Underwriters Laboratories are teaming up to reconcile - or “harmonize” - differences in test procedures in the solar module manufacturing industry. The IEC’s goal is to certify standard test processes for all solar module components.
Testing standards will ensure that manufacturers of components base their quality and performance claims on the same tests. That will protect the manufacturers that put the components in their solar modules and the customers that buy them.
The IEC’s Photovoltaics Material Project Team consists of 88 international members representing all major stakeholders in solar module component production and testing: module, adhesive, backsheet, frontsheet and encapsulant manufacturers; industry experts; certification bodies; and national laboratories.
The team is creating a matrix of testing procedures to ensure solar module components comply with IEC standards 61730, 61215 and 61646, which all pertain to photovoltaic material safety and performance.
The project team’s initial focus is on developing standards for backsheet testing. Backsheet laminate was originally made about 30 years ago using Tedlar, a fluorinated polymer developed and sold by DuPont. The original backsheet construction was Tedlar/polyester/Tedlar (TPT).
The backsheet acts as an electrical insulator and must also protect against the following impacts: ultraviolet radiation; temperature swings from -40°C to +85°C; humidity and vapor; dryness, wind, dust and sand; and scratches during installation and maintenance.
Initial backsheet safety and performance standards are concentrating on four areas: partial discharge, bond strength, volume resistivity and creep. Quality control testing will evaluate backsheet testing for hazards such as electrical shock protection, mechanical strength and flammability. Backsheets will be tested when they are new and after environmental aging - both at normal operating temperatures.
Tests will address the causes of hazards, including optical degradation, shunting, increased series resistance, moisture ingress, corrosion and de-lamination. It will break each hazard down by its potential causes and match the causes with tests and test methods. The result will be a matrix of conforming tests for the major causes of every hazard. Ten causes of failure are associated with the hazard of electrical shock, for instance.
When the project team is done, each cause will have a test and a test method associated with it. The test methods are from established engineering organizations such as IEC, SAE International, ISO (International Organization for Standardization) and ASTM International (formerly American Society for Testing and Materials).
When the IEC system takes hold, backsheet manufacturers that use less-than-stringent testing methods will have nowhere to hide. If they claim their backsheets will last 25 years before they start to degrade and they are not a certified IEC shop, buyers will know they might be buying an inferior product.
For example, for a manufacturer to say it meets the IEC standard for electrical strength testing, it must certify that it has used either IEC test method 60243 or 60216-5 - and be ready to document that claim. For mechanical protection from tearing, the manufacturer must have tested for tensile strength and tear resistance using ISO 527-3, ASTM D1004 or IEC 61730-2.
For some tests, such as water ingress from de-lamination, manufacturers will have only one approved method, ISO 62. Manufacturers will be subject to UL audits to confirm they are complying with testing requirements.
The IEC efforts demonstrate the will exists to reconcile quality standards for solar module components. With support from solar module manufacturers, who will benefit from them directly, the standards can take hold. They will enable manufacturers to seek out the lowest-cost suppliers without playing Russian roulette with quality. S
Process: Manufacturing Cost-Reduction
Manufacturers Beware: Backsheet Quality Varies Among Suppliers
By John F. Jordan
Switching to less-expensive backsheets can reduce manufacturing costs, but some vendors’ offerings may not be durable.