To the editor:

I generally agree with Dave Hardesty’s advice (“Watch out for ‘experts’ in Whidbey PUD debate”) concerning caution in who and what to believe. Following that precept I would like to urge a bit of discretion when reading Dave’s information regarding solar energy.

As the viewpoint stated, the most efficient photovoltaic (PV) modules commonly used for electricity production are between 12 percent and 17 percent efficient in bright sunlight. While that may not sound great, it’s much better than the best plants (photosynthesis) at ~7 percent. That efficiency translates to a 10-by-30-foot area of south-facing roof being able to produce up to 4,700 watts of power. That’s pretty good use of roof space!

Dave stated, accurately, that cloud cover, sun angle, and atmospheric filtering affects the output of PV panels.

However, our location on Whidbey is not a detriment. In fact it’s an advantage. We can annualize solar production with “net metering” — getting credit from the power company for excess solar production. Although winter weather and sun angle indeed reduce solar energy production greatly, we more than make up for it with our normally long, clear, cool (PV output is better the cooler the panels are) summer days. On an annual basis, a solar system on Whidbey Island can actually have better production than the same system installed in a hot, smoggy location in California.

For folks living off the utility grid, the low winter solar production and long nights are an issue that requires batteries and usually another method of energy production. However, most of us live with utility power and can use that to our advantage.

Dave stated that the lifespan of solar cells are around 20 years. The warranties on PV module power production is 20 to 25 years. There are 40-year-old PV modules that are still producing energy. The PV modules made currently are much better made than 40 years ago. Thus, we really don’t know what the lifetime of a PV module is.

I have never heard of any solar installations routinely changing out the PV modules every six to eight years, as Dave claimed. The solar industry commonly uses ½ percent per year degradation factor in calculations, although I haven’t seen even this much reduction of energy output over time.

There is a lot of information “out there”, including our Web site www.whidbeysunwind.com, about which to be cautious. I’m one more “expert” to watch out for.

Kelly Keilwitz

Whidbey Sun & Wind, LLC

Coupeville