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One contract I’m working on wanted me to develop “flexible” solar panels.  When I asked what qualities are important to the project, none of them included mechanical flexibility.  In finding a design solution for this customer, I learned that flexibility is an attribute people like the thought of, but may not really need.

Flexible solar panels are like the toy at the bottom of a cereal box.   I get excited about the thought of playing with them. I imagine bending, rolling and unrolling them, showing them to my friends, or even throwing them over my shoulder like a cape and running around while I power batteries.  The opportunities are truly limitless.

But then I look at the price and decide to reach for the generic brand corn flakes solar panel.  There is no toy in this box. In fact, there isn’t even a box.  It’s just cheap, sometimes energy dense, and usually made in China.  Dreams smashed.

Why was I attracted to the flexible panel in the first place?

In all of my encounters in the solar business, the metrics that matter for a solar panel are:

1. Cost—cost of the panel, out of pocket expense?
2. Weight—how portable is it? How easy is it to install?
3. Durability—how rugged is it in the field? Can I attach it to a jack-hammer?
4. Lifetime—what’s the payback period? NPV? IRR?
5. Efficiency—coupled with cost & area to get cost/watt

(other metrics are permutations of the 5 listed above).

It seems that flexibility implies a combination of a few nice attributes: cost, weight, durability.   But in reality, no markets ask for this complete set. Take a look at the chart above.  Here are the major markets for solar:

1. Utility—projects are financed on NPV and ROI basis.  Technology agnostic.  Cost per watt driven unless area (land) constrained, which is rare.

2. Residential—similar to 1 but with more concern for upfront cost & out of pocket expense, may be area constrained on smaller rooftops.

3. Commercial—similar to 1 & 2 with niche in BIPV, where aesthetic value may be valued over returns. May be area-constrained on smaller rooftops.

4.  Portable power—cars, boats, bikes, efficiency, W/kg, W/area, often area constrained and concerned with durability.  Will pay premium for substitution of heavy batteries.

5.  Personal power—chargers, bags, efficiency, mechanical toughness, will pay premium to enable usage of electronic devices off-grid.  Highly area constrained.

However, there are very few applications where all of these attributes are necessary.  Rooftops are designed to withstand the weight of a traditional glass panel, while people buying portable laptop chargers don’t really care about their generated cost per watt.  They just want to use their laptop on a jobsite in rural Africa (yes we’re always price sensitive, but not as much as other markets).

“Yes but installation costs are lower when you can just roll them on the roof” you may say?

I would argue that cost savings comes from eliminating racking systems, not the act of rolling.  Flat, rigid, lightweight panels can be laid out in the same way at very similar cost. The bottom line is that a rollable form-factor offers a low value-add.

What’s the opportunity?

There’s a disconnect between what markets want and manufacturers deliver.  We’re seeing low-efficiency, flexible panels going into BIPV markets (where cost still matters along with aesthetic), and portable/personal power markets (where efficiency matters most).

These thin film efficiencies are increasing (see Nanosolar, Unisolar, & Global Solar), but panel lifetimes will need to be proven before financiers will risk 20 year returns on a technology with little value-add over Kyocera or Sharp’s Silicon or First Solar’s CdTe panels.

What this leaves is an opportunity for efficiency & cost per watt leaders to come up with clever packaging techniques to make their panels lighter and foldable so they can penetrate portable and personal power markets.

I look forward to sharing my solutions to this space and the status of the project once it is publicly available.

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