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Issue #209 December 2007
INTELLIGENT ENERGY SOLUTIONS
Solar-Powering the Circuit Cellar
Part 1: Preparing the Site
by Steve Ciarcia
Have you considered installing a photovoltaic (PV) system at your home or office building? Steve recently took the plunge. In this series of articles, he describes the entire process, from site preparation to completion. Are you up to the challenge?
Start | Getting Started | So, How Do I Describe this Project? | Location, Location, Location | The Solar Panels Are the System | What's Next | Sources & PDF
Honey, I feel like starting a project. ;-)
That’s how all of this started about nine months ago. As I said in my editorial last spring, “If it can be installed at my location (without clear-cutting half the county), I’m going to install a photovoltaic power-generating system” (“Keeping the Lights On,” Circuit Cellar 202, 2007). Now that construction is well under way, I think I can start describing the whole adventure—and indeed, that’s how I’d portray installing a photovoltaic (PV) system.
Ever since building my first solar-powered gadget 25 years ago, I’ve been fascinated with the idea of solar electricity. We may not think about it every day, but certainly the GPS in our cars and the satellite radios and televisions that we’ve come to depend on couldn’t exist without solar panels. In fact, the entire space program probably couldn’t exist without PV power.
As for personal use, PV technology remained an expensive novelty for many years. I remember paying about $25/W for the solar cells I used in those early gadgets. It was still around that cost until about 10 years ago when cost reductions in silicon wafers started improving PV price performance. For the most part, PV power production up until recently has been limited to people so far removed from the power grid that making their own power has been their only alternative.
But recent developments in PV engineering and manufacturing now make generating your own power a reasonable choice and not a whacko idea. More importantly, I have never liked waiting to use new technology, and for me, the engineering price/performance of PV has hit the threshold where I finally feel I can make a sincere environmental choice that isn’t just talk. In all fairness, however, I need to clarify something right up front. Virtually all of the solar installation articles that you’ve read have talked about using PV to save money on your electric bill and included calculations for the return on investment. Certainly, cost discussions and a few dollar figures will pop up as I describe my installation, but try to ignore any logical (or illogical) conclusions about costs. At the present-day price of solar panels, a large commercially installed PV system is still an insane undertaking without government rebates and financial incentives. I certainly understand the benefits of offsetting my $0.20/kWh Connecticut electric rate with a little homegrown power, but saving $2,500 a year after dropping a suitcase full of cash to build this puppy is little consolation. I have to believe the engineering experience and the social benefits justify my expense, and I’ll just try not to look too hard at the cost details for a few years. ;-)
In this series of articles, I’ll describe my specific PV system, how I got there, what’s involved, and how it was built (see Photo 1). Later on, after it’s been running for a while, I’ll come back and discuss the results. The end product of this exercise is anything but conventional and simple. It’s not meant as a DIY construction manual, but I will attempt to include sufficient technical detail so you can understand why my system was built in this fashion. If you decide to jump off the same bridge, at least I’ll have told you where the rocks are.
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| Photo 1—Approximately 4,200 W of PV power is generated from 20 roof-mounted SunPower SPR-210 solar panels. The other 6,560 W comes from pole-mounted arrays behind this area. |
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