Not only will atomic power be released, but someday we will harness the rise and fall of the tides and imprison the rays of the sun. Thomas A. Edison

Wednesday, March 23, 2011

3M Awarded $4.4M to Develop Ultra Barrier Solar Film

According to the U.S. Department of Energy (DOE), 3M has been awarded $4.4 million by the DOE SunShot Initiative. The purpose of this initiative is to reduce total costs of photovoltaic (PV) installations by 75% in order to be cost-competitive with other sources of energy. Funds will be disbursed to 3M over a 3-year period.

So, what is 3M going to be doing with this money? The company will accelerate development and marketing of their Ultra Barrier Solar Film. During this time, 3M will be working with DOE’s National Renewable Energy Laboratory (NREL) outside Denver, Colorado to demonstrate performance and reliability.

So what is this film used for? The intent is to substitute glass with a flexible film. Why is this important? Well, there are a few difficulties with traditional glass:

- Glass is heavy. Care must be used to prevent overloading of a rooftop installation.
- Glass is rigid and inflexible (reminds me of some people I know).
- Glass-covered PV arrays are limited in their size to make them manageable for transport and installation.

How is Ultra Barrier Film better than glass? According to 3M:

- Ultra Barrier Solar Film requires less installation time.
- It removes the need for metal racking (installed to keep glass PV arrays from overheating and providing the perfect hiding place for your kid’s frisbee).
- By reducing logistics expenditures (logistics… think UPS). It weighs less, is flexible, and therefore less expensive to transport.
- The film allows manufacturers to commercialize large area modules, effectively reducing fixed costs associated with module manufacturing, assembled in a continuous roll-to-roll process.
- An effective film barrier would allow for permanent installation of inexpensive, light-weight PV arrays that are flexible and follow the contours of the surface they are attached to.

The reason that glass is used in the first place is to keep dirt and moisture out while allowing the maximum amount of light to reach the semi-conductor material. 3M claims that Ultra Barrier Solar Film has “high light transmission, superb moisture barrier performance, and excellent weatherability”. Weatherability must include resistance to ultraviolet (UV) rays that are well-known to degrade plastic over time. To be truly effective, a homeowner will expect his or her array to last as long as the mortgage (up to 30 years).

Moisture is troublesome if it gets inside a PV array. The stated performance for Ultra Barrier Solar Film is “moisture vapor transmission rates (MVTR) below 5 * 10-4 g/m2/day”.

OK… so what is that?

10-4 is another way of saying 0.0001, so the amount of vapor transmitted through this film is 0.0005 grams (a gram is about the weight of one paper clip) of water over one square meter (a meter is 3.3 feet) per day. In other words, it would take 10,000 days (27 years and 3 months) for 5 paper clips worth of water to accumulate over a 10 square foot area). That’s pretty dry.

Will the reality match the hype? I’ll let you know in a couple of years when I will be reporting from my local hardware store.

1 comment:

  1. Hi Bruce,
    Thanks for your nice post. I am not an Engineer like you.But do you know what? I hate all Carbon energy (Coal+oil+gas+others) . Recent Japan's nuclear crisis is the ans that we need Green Energy mostly. and increasing the price of oil price is also encourage to Green Energy or Renewable energy . I love top-roof solar panel (but it should be more powerful.

    I hope our world will be a more comfortable for living again.