Sustainable Energy Final: Solar Variations

I was forced to put aside my previous final, a turnstile dynamo using the MTA gates, when I could not find sufficient data to propose a mechanical improvement to the gates that would make them easier to turn. This was important because adding a dynamo would make the gates harder to turn, so I needed a way to balance that out.

Instead I turned to a topic that has interested me for a long time: Aesthetic improvements on photovoltaic installations. In short, why can’t solar be beautiful?

“Aesthetic designs seem to trigger certain positive
responses in consumers such as an immediate desire to own the
product (Norman, 2004); a higher willingness to pay for it
(Bloch, Brunel, & Arnold, 2003); and an increased inclination
to show off and care for that product (Bloch, 1995).”

Solar panels look the way they do because it makes the most efficient panels with the simplest manufacture process. They are utilitarian and do not integrate well into their surroundings.

Efficiency, however, currently ranges between 2% (solar inks) and 26% (monocrystalline in lab conditions), with an average of 10%. We routinely sacrifice aesthetics for efficiency gains of only 1%. Do we have to? A larger market would open up if more home and commercial locations expressed interest in solar. Currently the main draw for solar is saving money, and it comes with an aesthetic cost. If instead there were an aesthetic improvement, the market would look very different indeed. Say for every 1 house at 10% efficiency we could instead have 10 houses at 9% efficiency. That’s an 80% improvement in overall energy savings.

I also believe that aesthetic appeal frequently trumps logic in home and business design. For solar to thrive, there must be a wider market base willing to purchase and install cells. More early adopters now boosts the industry, helping drive down manufacturing costs.

Potential buyers could be convinced to invest the money if only solar installations could be appealing and low-maintenance. Most solar panels are glaringly obvious as a “tacked on” architectural element, detracting from the cohesive appearance of a structure. Treating solar as an integral design element is the first step towards increasing adoption of the technology. There is a great deal you can do with rectangles, as a millenia of brick-laying has shown us. But solar panels offer no variety in their cell patterns or their overall shape. More complex shapes are achievable, but expensive.

Here is an example:

The wide flat panels maximize potential energy transformation. An even rectangle versus an n-gon with angles smaller than 90′ means no solar cells are wasted (the cell must be whole to produce power, and a square cell does not wholly fit into a 60’reoiin gv angle). This ensures that a panel with surface area of 100 m^2 works at full capacity. A similarly sized pentagon, with 100 m^2 surface area, would lose approximately 20 out of 120 possible solar cells (4 at each vertex, times 5 vertices). So it would have 83% its potential efficiency.

While efficiency is good, it would be even better to have a wider adoption base for solar energy. Consider this: The two most-cited pro-solar arguments for converting to solar energy are saving money (by going off-grid), and saving the planet (via reduced carbon emissions). Try entering “Why switch to solar” into a search engine, and aesthetic appeal will not be one of the results.

A list of pros and cons of the current solar options:

Cons –
Intermittency issues – inefficient in heavy weather conditions, nighttime, significant distance from the equator, shade from nearby structures.

Power storage in batteries is non-ideal. Flywheels or molten salt are not optimized for wide-scale use.

Low efficiency requires large surface area to provide sufficient energy for more than a few lights

Solar right now is expensive and ugly.

Pros –
Solar radiation bathes the planet at approximately 170 TW/m^2 (Smil, 2006), and is the most abundant renewable energy resource available.

Solar is quiet

Excellent on-site power for remote locations, allows for grid independence

Peak energy needs typically coincide with peak solar panel efficiency

Extremely low maintenance fees after capital investment

Can be mounted on roof or in fields, without taking up the area of a traditional power generator.

Of the above list, aesthetic value is something we can do something about right now, without requiring changes in basic photovoltaic crystal manufacture or power coupling.

Improving the appearance of solar panels requires understanding why they appear as they do now. In solar cell manufacture, there are several basic mechanisms which each have a characteristic shape.

Powerfilm thin film pv are flexible enough for a wide variety of artistic installations, allowing them to curve around a variety of surfaces and fold for storage.

The best way to integrate something like Powerfilm into home energy setups is with designs which incorporate the power leads and transformer. Instead of a limitation, this design constraint could lead to more creative installations. Geometric shapes and abstract line art are a good starting point.

I tested a remarkably simple method to change the appearance of Powerfilm strips. I added a thin pigment layer (using store-bought Sharpies) over first the metal conductors around each cell, and then on top of the cells themselves. Using a voltmeter to measure open-circuit voltage on several panels in noon sunlight inside the ITP lounge, I measured no difference between the colored and clear strips.

Sharpie panel

With some sharpie

All sharpie

When I contacted Powerfilm regarding tinted panels, I was informed that their cells had a paired high and low frequency setup which required both red and blue light coming through to generate power. However, I tested pink and light blue sharpie as well as dark brown, orange, yellow, and green sharpie and found no discernible performance change. While there may be a 1% difference measured in ideal lab conditions, in working conditions I found nothing concerning. Colored solar panels are possible. Paired with colored fabric or architectural elements, this paves the way for truly artistic solar patterns. A single pigment addition step in the final steps of manufacture could provide such colored panels without increasing overall production costs. Below are a few suggestions for colored, patterned solar panelling.

From around the web, here are some more creative suggestions:



Konarka's semitransparent photovoltaics in limited colors


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