False: I should wait for new technology to go solar

Did you get an iPhone or an iPod Touch for your most recent birthday? Have you taken Google’s Chrome for a test drive yet? What about cloning Fido or Fifi? (Mmm, maybe that hasn’t caught on quite yet…) Here in Silicon Valley especially, it’s easy to get caught in the “upgrade” mindset. And with such a focus the latest and greatest, it’s no wonder there’s confusion when conversations about home solar and technology cross paths.

The key thing to remember is that PV ≠ PC.

In other words, photovoltaic (PV) solar technology (i.e. traditional silicon-based solar panels) doesn’t obey the same rules that have governed the personal computing industry where you buy the most cutting-edge laptop and realize it’s out of date 6 months later.

The truth is, over the many years we’ve used PV technology, it’s changed very little; in terms of panel efficiency, it’s been a story much more about the tortoise than the hare. Over the past 20 years, we’ve seen a gradual 0.5% increase in efficiency per year. And, it’s likely to continue in the same way.

(image courtesy of http://www1.eere.energy.gov/solar/)

“But what about thin film technology?” you might ask, referring to the new generation of low profile panels, “Won’t it revolutionize the solar industry because it’s so much less expensive to produce?”

Don’t call me a thin-film hater, because I’m just as excited as the next person, but realistically it’s going to be awhile before thin film is the best choice for your home solar system.

While less expensive to manufacture, thin film is also less efficient. Residential thin film conversion efficiencies typically range between 6% and 10% while PV ranges between 13% and 19%*. (And for those of you who just scoffed at the numbers, just consider that the shiny new hot rod in your driveway converts its gasoline at only a 20% efficiency). What these numbers mean is that you have to buy many more panels to produce the same amount of energy for your home, and you need a lot more quality roof space to fit those panels. Most homes simply don’t have that space, as Michael Holman of Lux Research explains in his NY Times blog post on Sept 11 2008. And of course purchasing those additional thin film panels will mean that the total cost of your thin film system won’t be much less than the total cost of a PV system.

Another interesting point to consider about the difference between PV and PCs is that each new PC (theoretically) works better than the last while electricity is electricity is electricity; the newest solar panels might convert more sunlight into energy but they’re not going to produce better electricity.

Yes, PV will improve, but not at a rate that makes waiting to go solar smart, especially in light of skyrocketing electricity prices. Just think of all the money you could save on electricity while you wait.

*”Solar Finance” presentation on July 16, 2008 by Travis Bradford, Prometheus Institute.

This entry was posted on Tuesday, September 9th, 2008 at 3:25 pm and is filed under Solar Technology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.