The solar PV industry has experienced phenomenal growth and widespread popularity as an alternative source for creating electricity. Government policies and incentives have proven to be important enablers to industry growth. However, incentives can’t continue forever and the industry needs to continue to drive down total costs in order to remain competitive to alternative energy sources and open new markets. As industries and products mature they learn how to drive down costs through ever greater application of “plug-n-play.”
Plug-n-play standards leading to greater economic growth and consumer benefits have been with us since the dawn of the industrial age. The most recent “poster child” in our consumer electronics economy for a hardware “plug-n-play solution is the Universal Serial Bus (USB). This enabled a whole category of computing peripheral devises for consumers in terms of both solution variety and sales volume. Can similar concepts be applied to solar PV installation cost reductions? If the consumer electronics industry can come together and define standards that streamline and grow their business, can the solar PV industry take note, and do likewise? The easier it is to design and install PV systems, the more PV systems a typical crew can install per day, achieving a huge productivity gain while not impacting, profitability, quality and safety.
SolarTech, under a SunShot grant through the Department of Energy, convened leading industry experts in several workshops starting in Dec. 2012 studying several possibilities from integrated electronics in the modules to dimensional standards for cables and modules. The key to any successful industry standards collaboration is identifying an issue that has economic significance while not overly burdening any single subset of the industry. One issue all participants supported, and serve as an initial step to other standardization possibilities, is standardized module geometries.
There have never been standards for the size of solar PV modules as each manufacturer creates its own solution in its own way. This has resulted in a plethora of options but it also created several complications that have added soft and hard costs to solar installations. Some see this as a competitive advantage, but the case for standards was best articulated during the SolarTech InterSolar North America 2013 Performance Symposium, “Hertz and Avis don’t compete on the quality of their rental agreements.” The same can be said of module geometries. Energy consumers simply want (demand) low cost energy ($/kW-hr), and if this means a solar PV system investment, then the lowest cost overall system cost and ongoing maintenance is required for competitiveness. Standardization on 60- and 72-cell module dimensions will take cost out of the installation of solar PV without compromising integrity or reducing profitability, and offer many unobvious benefits as well as the obvious ones:
First, is the requirement to create a new set of calculations with each design. One installer used the phrase “re-inventing snowflakes” since each module design is unique; each installation requires a new set of calculations. If there is a change of module manufacturer in the middle of project, another design calculation is required costing additional design time.
Other soft costs include incorrect hardware arriving at the construction site; module selection changes during the design impacting the racking design; and the growing material cost issue in microinverter applications is due to off-center bus connections with the module centerline.
The final word on costs will begin to take shape in a few years as consumers begin replacing failing modules in the earliest systems. There is a growing buzz in the industry for higher installation quality standards and multitude of Operations and Maintenance issues as earlier systems begin requiring attention. The industry will suffer significant negative PR if consumers find that the whole array requires a major overhaul just to replace one failing module in the center of the array, because nothing could be procured to meet the physical and electrical specifications of an obsolete module. Now is the time for the industry to be proactive.
To address the above issues, SolarTech enlisted a module standards team from the December 2012 workshop participants to identify a definition path for 60- and 72-cell crystalline silicon solar module standards. The committee analyzed several factors with the goal to define a proposal best serving the entire industry.
Determining a simple set of three dimensional numbers isn’t an easy task. Module performance can be impacted by tight inter-cell dimensional tolerances, and concretively large inter-cell dimensions reduce footprint efficiency. Two such issues are illustrated in the following figures.
Illustrations of shading and soiling problems in low pitch angle configurations.
Shading and soiling implications of the frame spacing occur in low pitch applications. It is a well-known performance degrading phenomenon that if the single cell illustrated is compromised by such issues then that cell impacts the performance of the entire string it’s connected to in the module.
Allowing more space between the edge cells and the frame wall reduces potential long term problems with shading and soiling. Multiple module manufacturers were consulted, numerous criteria were examined, and the best outcome is the following proposal for a standard geometry for a 60-cell and a 72-cell module:
- For a 60-cell module, the size is 40 mm by 1000 mm by 1664 mm
- For a 72-cell module it is 40 mm by 1000 mm by 1980 mm.
Having a standard thickness will greatly simplify the clamping solution and a consistent width of a simple dimension (one meter) will also greatly simplify project estimation and the installation design.
The workshop and standards team participants estimated that implementing the above dimensions will reduce the installed cost of solar by as much as $.10 per watt without compromising quality and without affecting profitability.
The following companies support the standardization proposals of SolarTech and the efforts to lower soft costs:
- Schletter
- DPW (Direct Power)
- Unirac
- Professional Solar Products
- Creotecc
- Petersen Dean Roofing
- Sungevity
- RealGoods
- REC Solar
- Chevron Energy Solutions
Next Steps
This story concludes with three calls for action that the industry needs to take ownership of:
- Final ratification by the module manufacturers, and commitment to proceed with incorporating into their new product roadmap. SolarTech and the participants who worked together to draft the proposal believes the proposed dimensions as technically sound and offer a practical solution in the consumer’s interests. A standard is only as good as its adoption penetration.
- If adopted as proposed, SolarTech and the standards supporters anticipate implementation of these proposals would integrate into the module manufacturers existing new product roadmap. Since all manufacturing changes to existing products is expensive, and product changes undergo recertification testing, it is more appropriate to roll the adoption of these dimensions into the next generation product development roadmap.
- The standards conversation shouldn’t end here with this small but significant step for the industry. Standards have played an integral part of scaling every industry. As implied earlier, there are other opportunities for standardization while still maintaining an individual companies competitive differentiator: integrated electronics, mounting hole size and location standards, cabling, racking, etc.
Doug Eakin has fulfilled the position of SolarTech Installation Committee Chair since SolarTech’s inception in 2008. Doug has led many successes for SolarTech to define solutions reducing the hidden cost of solar PV installations; one of SolarTech six core initiatives. Doug’s fulltime career position is in solar business development. Doug recently took a position with Lapp USA as OEM Sales Manager.
Lead image: Solar panels via Shutterstock
