Plug-And-Play PV Modules Could Cut Soft Costs On Solar Installations


U.S. solar photovoltaic installation costs appear to be fairly excessive relative to other leading solar markets in Europe. Because labor rates are fairly similar, there must be other factors at work.

SolarTech, through a grant from the Department of Energy's (DOE) SunShot Initiative, has been leading a series of industry workshops to identify opportunities to lower costs through standards leading to more effective ‘plug-and-play.’ In particular, the effort has focused on removing soft costs from the PV installation process.

Soft costs are often termed ‘hidden costs,’ as they are not standard line items on a bill of materials or labor rate. In the solar PV world, these are the costs related to permitting, inspection and utility interconnection; finding or training an adequate workforce; securing financing or losing deals because of inadequate financing options; energy production confusion due to inadequate performance standards; and installation inefficiencies and productivity.
Last year, the National Renewable Energy Laboratory published a study indicating that over $1.52 per watt is spent on soft costs, of which $0.59 per watt is installation cost. The DOE SunShot program has set a national goal of lowering the soft cost stack to $0.80 per watt by 2015. Clearly, the $0.59 per watt number has to undergo significant improvement in order to satisfy the cost goal.

More effective installation best practices and standards have been of particular interest to SolarTech's mission, and since December 2012, SolarTech has conducted three industry workshops examining the opportunities and solutions. These workshops have uncovered the industry's concern that simple price reductions will only create more bankruptcies and compromise quality.

One issue all participants supported, and that serves as an initial step to other standardization possibilities, is standardized module geometries. Standardization on 60- and 72-cell module dimensions will take cost out of the installation of solar PV without compromising integrity or reducing profitability. There have never been standards for the size of solar PV modules, as each manufacturer creates a 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.

First is the requirement to create a new set of calculations with each design. One installer used the phrase ‘re-inventing snowflakes,’ as 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 a project, another design calculation is required. The additional time spent in recalculations would be mitigated by having a standard geometry for 60- and 72-cell modules.

Another soft cost in the process is incorrect hardware arriving at the construction site. This can happen by confusion of module choices and/or mistakes in the research of module dimensions. Productive time lost through installation delays and additional effort spent correcting the mistake is a hidden cost to the installer.

A third soft cost can originate with a module selection change during the design. The racking manufacturers create a bid for the support structure based on the original definition of the project. However, the definition often changes due to module changes, and this forces the racking manufacturer to spend additional resources recalculating the project.

Additional soft costs in the form of material costs can be incurred through the lack of standards. Because clamping and racking hardware may see a variety of modules, the racking manufacturers are forced to provide many alternative options and/or very flexible hardware solutions. This obstructs economies of scale and interferes with future price reductions.

To address the aforementioned issues, SolarTech enlisted a module standards team from the workshop participants to identify a definition path for 60- and 72-cell crystalline silicon solar module standards. The process involved asking six module manufacturers to give their definitions of the correct cell and border spacing. The committee responded, and their inputs were analyzed. The results were averaged, and the calculations were then slightly modified to provide results that best serve the entire industry.

Allowing more space between the edge cells and frame wall reduces potential long-term problems with shading and soiling. Multiple module manufacturers were consulted, numerous criteria were examined, and when the results were inserted into the module spreadsheet, the best outcome was 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 1,000 mm by 1,664 mm; and
  • For a 72-cell module, it is 40 mm by 1,000 mm by 1,980 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 aforementioned dimensions will reduce the installed cost of solar by as much as $0.10 per watt, without compromising quality or affecting profitability. By having the industry collaborate on these dimensions, the solar community will intelligently reduce an unnecessary cost and further accelerate the growth and adoption of solar PV. Plus, future replacements of modules will be much more practical and cost-effective and would be a positive industry image.

The standards conversation should not end here with this small but significant step for the industry. More can be accomplished if the industry seizes on the momentum. As implied earlier, there are other opportunities for standardization while still maintaining an individual company's competitive differentiator: integrated electronics, mounting hole size and location standards, cabling, racking, etc. Anything that accomplishes plug-and-play will shave multiple pennies off of the cost stack and ultimately grow the business.

Standards have played an integral part of scaling every industry. The solar PV sector needs to continue meeting, identifying, prioritizing and driving the definition of more standards.

Doug Eakin is SolarTech's installation committee chairman, and David McFeely is SolarTech's director of grants and government programs. They can be reached at 408-943-7061. Visit the website at

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