Tuesday, September 22, 2009

Solar Education

Determined now to figure out what it would take to tap into the sun's power for residential electrical generation.  What I discovered is that it is no longer 'rocket science' and that there are commercially available solutions.  I also learned that it's still an immature industry and that there are only a handful of installers in our area.  And finally, I learned that the Federal Government's 30% renewable energy tax credit is indeed ramping up interest and causing some interesting responses by the installers.

Not Rocket Science

  • Everything is basic electronics.
    • Solar panels
    • Inverters
    • Wiring
    • Safety components
  • High-voltage DC is usually involved.
  • The concepts are relatively easy to understand for someone with an engineering background.
Commercial Solutions
  • I would only ever use commercially available, off-the-shelf components.
  • Solar panels come in a variety of types, configurations, prices and efficiencies.  They all output DC.
  • There are many types of inverters available.  Some connect to your utility and some charge up batteries.  (I will only discuss the former, also known as grid-tied inverters.)
Installers
  • People are anxious to get into the solar installation business.  There's good money to be made, particularly from those who are proud 'early adopters'.
  • The three installers in my area from whom I got a bid unanimously marked up the system components by 30% (in addition to specifying a labor fee).
  • There are some important concepts to understand before embarking on a solar project and these installers generally understand those concepts.
Where can you go to learn about residential solar?
  • Subscribe to Home Power Magazine.  Get the on-line subscription and read the archived articles.
  • Purchase Photovoltaics: Design and Installation Manual from SEI (Solar Energy International).  Make sure to get the most recent edition.  Do the exercises.
  • Now go back and re-read some more articles in Home Power Magazine.
  • See if your local community college has any courses on solar power.
  • Talk to people who have already invested in solar power.
  • Rinse and repeat.
I'm an engineer and have fooled around with electrical systems since I was a kid and I'm comfortable doing most of the work associated with this solar project, but that's only after studying and researching for about two years.  Even with that training, however, I'm not a licensed electrician and so will hire and supervise an electrician for the installation.  It's unlikely the electrician with whom I work will have any solar PV system experience nor will he have any high-voltage DC experience.  But the principles are straightforward and after reviewing the code and NEC requirements I am confident in a safe and reliable outcome.

If you are thinking about doing a solar PV system on your own then you certainly should be very comfortable with:
  • Solar panel and inverter sizing calculations.
  • 110/220 VAC systems.
  • Interconnecting with the utility.
  • Handling high-voltage DC (~400-600 VDC).
  • Truss load bearing for a roof-mounted system.
  • Local code and permit requirements.
  • Utility interconnect requirements.
  • Subdivision architectural/CCR restrictions.

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