Sunday, May 11, 2014

Solar Power Helps Environment, Pocketbook

Published in the Sun May 7, 2014

Bill Stump puts the finishing touches on the racks fro a solar array on 18th street

In 1973, when the engineering department at UT finally decided that students could use calculators in class, my husband Bill put his slide rule in the drawer and we headed to the University Co-op for a major purchase.  He picked out the deluxe calculator that could do square roots as well as add, subtract, multiply, and divide.  That was all it could do, but it set us back more than $200, which was about 50 date-night enchilada dinners at El Patio.  These days you can get a free calculator on a key chain, but that’s the way technology evolves.  The early adopters pay more.

Another technology with a plummeting price is photovoltaic solar panels, as I can attest from personal experience.  In 2006 we bought ten solar panels (a 2 kilowatt system), with the required DC to AC inverter and roof racking, for $12,960.  We installed them ourselves, which requires at least one person who understands electricity, and several others who are not afraid of heights.  If you don’t have the right kind of roof you will also have to put bolts through the roof, in which case you will definitely need somebody who understands roof flashing, because you will not like your solar panels if the roof leaks.  After a $2000 tax credit from the federal government, our cost was about $5.50 a watt.

Please note that this cost of $5.50 per watt has nothing to do with the cost that you might pay your utility company for a kilowatt-hour of electricity, which is about 11 cents.  A watt of generating capacity will produce a watt-hour of electricity every hour that the sun shines, day after day, for the next 30 or 40 years, maybe longer.  There are no moving parts to wear out, and maintenance is close to zero.  For the last seven years those ten panels have produced an average of 215 kilowatt-hours per month.  At night, or when the house is using more than the panels can provide, electricity is supplied by the grid.  During the day when nobody is home the panels are putting electricity back into the grid and the meter is essentially running backwards.  The switching back and forth all happens automatically.

This year we purchased a much bigger solar array for almost exactly the same price that we paid for the small array eight years ago.  The panels are getting more efficient at converting sunlight to electricity, so now we can get 5.6 kilowatts of power in 21 panels.  Even including the racks and inverters, the cost has dropped to $2.13 per watt.  Let’s say we get 750 kilowatt-hours per month from this new array.  At 11 cents per kilowatt-hour, the array would be producing about $82.50 worth of electricity a month.  Over 30 years that equals $29,700 worth of electricity.  If the market price of electricity rises, so does the profitability of the panels, because the sunshine stays free.  It won’t be too long before utilities start charging their customers more for electricity consumed at peak demand hours in the late afternoon, and that is exactly when panels are producing the most energy.

The precipitous drop in price of solar panels explains why last year 3900 megawatts of new solar generation capacity were installed in the United States.  Of new electricity sources installed in 2013, solar was second only to natural gas.

Of course the really cool thing about solar panels is that they produce clean electricity from sunshine, which is plentiful to the point of being a nuisance.  After the panels are built and installed, there are no CO2 emissions, no particulates, no smog, no mercury, no fracking, no water consumption, no noise, and no toxic spills.  Texas has all this energy from the sun relentlessly beating down on us.  Might as well get some benefit from it.


  1. It's not surprising that solar panels have been helping the environment change drastically for the better. After all, that's what it was aimed for. I just hope they make it much more accessible to everyone who would be more than willing to have it in their homes. Anyway, thanks for sharing, Bonnie! I enjoyed stumbling upon your blog. All the best! :)

    Rachael Massey @ Auto Controls

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