Tag Archives: solar power

A follow-up to:  Watt’s Happenin’? Solar Power is Watt.

Well, the first bill in is.  Not a bill for an entire month during which we generated solar power, but instructive nevertheless.

Our two solar panel installations officially went online about 1:00 p.m. on the afternoon of Thursday, May 17.  Our May billing cycle ran from May 2 through June 5, and was divided into two separate and distinct bills to reflect our switchover to net metering.

During the period from May 2 until 1:00 p.m. on May 17, we used 429 kWh, which resulted in a charge of $47.68.  From 1:00 p.m. May 17 through June 5, total net consumption was 71 kWh for which we were charged $12.93.

But a breakdown of this 19½-day period reveals an even more detailed picture of what actually transpired energy-wise: Our total net metering energy credit was 536 kWh.  Household usage over this same time-frame was 607 kWh.  Thus, we were billed for 71 kWh of energy.  That means solar power generation covered 88% of our total energy bills from the time our solar panels went operational until the end of the May billing cycle.

How does all this compare with May of last year?  Good question.  In May of 2011 the billing cycle ran from May 4 through June 4.  Total usage during that period was 1,094 kWh, for which our El Paso Electric Company bill ran $130.08.  That means we used roughly the same amount of energy—1,094 kWh in 2011 vs 1,036 kWh for the same month in 2012—yet, our bill in 2012 was $60.61, or less than 47% of last year’s charge.  And remember—that’s with us generating solar power for only 19 ½ days out of the entire 33-day billing cycle, or about 59% of the month.

That’s not the complete story, however.  During that 19½ days we actually produced 970 kWh.  Yet, net metering only credited us with 536 kWh.  Thus, it appears that we only get credited about 55 kWh for every 100 kWh we put into the El Paso Electric Company power grid.  I knew going in that it wasn’t going to be a 1-for-1 exchange with the electric company, but until now I didn’t know what the actual rate of return would be.

June will be the true test.  That will be our first full billing cycle during which we generated solar power.  June historically is also El Paso’s hottest month, and thus it is the month requiring the most extensive use of energy-intensive air conditioning.  We’ve already had four days this June at or above 100°, and we’re anticipating triple-digit temperatures for six of the next seven days.

So, expect a more detailed cost-to-benefit analysis in about a month.

We love home shows.  Meandering the aisles at the El Paso Convention Center.  Browsing through all the latest neat stuff for the house.  Getting quotes from multiple vendors selling like products and services.  And, occasionally, you come out a winner.  Right now, Ursula and I are feeling like winners.

Just before our last transatlantic adventure, and after we’d obtained the necessary approvals from our home owners’ association, we contracted for a solar generation system for the house.  Unfortunately we were unable to get together everything we needed to install before embarkation, but within weeks of our return installation commenced.

The company is Border Solar.  The system they installed is from SunPower—32 solar voltaic panels (E19 / 240) rated at 240 watts each.  There are actually two installations here—one set of 18 panels over the back balcony, and another set of 14 panels installed over a south-facing roof visible only from the open-air courtyard around which our house is built.  Since there are two sets of panels, the total system runs through two inverters (pictured below).  Guaranteed annual output—a little over 13,700 kilowatt-hours (kWh), or somewhere between 95% to 97% of our home’s annual energy needs.

After weeks of planning, waiting, installation, waiting, more installation, and more waiting, the El Paso Electric Company gave their final seal of approval, installed a Net Power Meter and, on Thursday afternoon, the switch was thrown and power generation commenced.

So, how well is it all performing?  Beyond my expectations, actually.  SunPower’s system includes constant, internet accessible performance monitoring.  At any time I can log on and check current production; daily, hourly, and even 5-minute-interval production; production by inverter; and even production on previous days.  It’s sort of addictive checking to see how much energy you’re generating and, conversely, how much you’re saving on your electric bill.

On Friday, our first full day of generation we produced 51.54 kWh.  Saturday, Sunday, and Monday saw 52.40, 50.74, and 49.84 kWh.  If I’ve figured out our meters correctly, we’re using about 30.84 kWh per day and generating on average around 51.13 kWh a day for a net gain of some 20 kWh over and above our current usage.  Those usage numbers won’t hold during the rapidly approaching triple-digit temperatures we can expect in June and early July, but at least we’re banking some reserve in anticipation of some heavy air conditioning usage (last June our home energy use topped out at over 1,600 kWh for the month).

A quick word about net metering.  Net metering is a policy in use by some electric companies that gives you credit for excess power generated (which goes into their power grid).  The electric company then applies that credit during those times that you draw power from their system.  If your power company has such a policy, then that’s ideal for solar power.  You give the electric company your excess power during the day—when demand is highest and the company most needs it—and at night when you’re no longer generating power, you “spend” those “banked” energy credits when you draw from the electric company’s power grid to pop some corn and play a Netflix Blu-ray of True Grit, X-Men: First Class, Thor, Captain America, Dark Shadows, 127 Hours, or Nordwand.  How’s that for a shameless plug of my movie reviews?

The true test of course is billing, and June is historically our hottest month.  Last June we had our worst electric bill ever—just shy of $300.  This June is forecast to be just as stifling, perhaps even a bit hotter.  Needless to say, this coming July is the first time in my life I’m actually looking forward to receiving a summer-time electric bill.

Now some numbers for the ecologically minded among my followers:  During the period from Thursday afternoon through Monday evening we generated 228 kWh.  That 4 ½ days the system reduced our home’s carbon footprint by 392 lbs.  That’s the equivalent of planting four tree seedlings and growing them for ten years, or not driving the average car 373 miles.

Below is a (censored) photo-journal on the system and its installation: