One Solar Picture Requires 1,000 Words (Less I Hope)

In this era of electronic based info, I keep my reading of the Sunday papers on paper. Today's (Sunday, September 6) Chicago Tribune had a good article on solar power on the front page of their money & real estate section (7) (note: they lower cased it, so I will too!)at http://www.chicagotribune.com/business/chi-ym-solar-panels-0906sep06,0,1837476.story. It was a good article, but noteworthy to me was the graphic (got to buy the paper to see it). The graphic is a two panel array angled over a gable window. It's noteworthy because as the ancient saying goes, that picture of two solar panels will stick in readers' minds, and maybe their decision making, on solar.

My concern is that readers will see those two panels and think that's all it will take to power a house, though I will be amused if they connect the two panels with the $20,000 and up price tag (before incentives) for systems that will provide a good chunk of your electricity.

So, a few comments on the graphic that may sound like nitpicking, but generating solar electric power is still a relatively rare deal in Illinois.

First of all, those are solar electric (photovoltaic) panels, not solar thermal panels. Hopefully in a few years, when solar panels in Illinois are as ubiquitous as Cub pennant drive collapses, I won't have to sound so elementary.

Those two panels are about 200 watts or so of capacity measuring about 16 square feet of area in total. In Chicago, they would generate about 300 kilowatt-hours (kWh)or so a year. The average house in Chicago uses about 7,600 kWh a year. Some might say, well, in the future research will improve the technology so that two panels that size will deliver that much electricity. Sorry, even if the panels were 100% efficient (a little tough to do), the most you would get is about 2,500 kWh a year. The best theoretical case in the foreseeable future is about 40% and I wouldn't hold my breath getting those from your home improvement store anytime soon. Yes, you can use reflectors and concentrators, but that's still way more area than 16 square feet of those panels.

Those two panels are either 12 or 24 volts each, which isn't sufficient to provide household voltage, a nominal 120 volts. Without getting into a design course here, you would need at least ten 12 volt panels or five 24 volt panels. Or, you could use the panels off grid for a small application like direct current fans. I have one on my house, a PV panel directly connected to a roof vent fan - when it's sunny, it vents, cloudy or dark, it doesn't. Or, you could use a transformer to step up the voltage, but that could get messy. Or, you could use batteries, but that could get messier for the average homeowner. To paraphrase "Apocalypse Now", 'I love the feel of battery acid on my hands in the morning'.

Anyway, what you'll probably need is at least 100 square feet or so panels, which will be about 1,000 watts or so capacity and cost around $8-12,000, depending on how good a shopper you are and how easy the installation is. That's sort of a starter application for a grid connected home, that will get you 1,200 to 1,500 kWh hrs a year. You can knock off 30% from federal tax credits, and if Illinois gets the rebates back, maybe another 25-30%. The more you add, the more electricity you generate, and you'll get some cost savings from economy of scale. Expensive? You can spend thirty to fifty grand redoing your kitchen or have no electric bill. Up to you.

One more thing, the suggestion made about using the panels to shade windows from the sun is a good idea, but the angle show is way too steep, more appropriate for a solar thermal panel.

Want to know more? The Illinois Solar Tour is coming up Saturday, October 3 (in most places), 10 AM - 3 PM. Check out the Illinois Solar Energy Association website at http://www.illinoissolar.org to find 140 buildings getting some or all of their power or heat from the sun, wind and earth. See them for yourself. There's bound to be a building or two near you.