A Modest Solar Panel Setup And How Well It Performs

The Next Big Move (to the present)

In late 2009, we stepped back into the housing market after a crash-hiatus. This meant I could configure my house any way I wanted, up to spousal approval. Okay. Eight panels this time. More power. More stuff connected. But extension cords running through the house was a non-starter. So I set about running standard household electrical cable through the house (attic/walls) to dedicated PV power outlets (colored gray) throughout the house in strategic locations. I put a breaker box next to the PV installation so the dedicated PV circuits would have over-current protection. At present, I have five outlets throughout the house running on PV, plus the direct-wired attic fan. The items powered by the PV system change a bit from time to time (no longer run TiVo; changed fridge; changed television). At present, we run:

  • Refrigerator (40 W average)
  • attic fan (on thermostat; can easily switch to utility as needed)
  • LCD TV (20–45 W when on, depending on Eco mode)
  • Entertainment cabinet (stereo, DVD/VCR, Roku)
  • Cable modem and wireless router
  • “Normal” locations of two laptop computers
  • Printer (hog when off, at 9 W!)
  • TED LCD display
  • garage plug for electronics projects, charging cordless tool batteries, etc.

History of electricity use in our household, showing the rise of the PV system. Many months of the year of late, our modest off-grid PV system provides more of our electricity than does utility. See the phantoms post for more on this plot.

The main configuration change in the new house—besides eight panels arranged as two parallel strings of four—is the requirement for a GFPD in the circuit. Because they sit atop our dwelling, the panel frames must be grounded, and a special breaker set between the ground and neutral buses that will also kill the power to/from the panels if current begins to flow to ground (e.g., if a short at the panel connects the positive terminal/lead to ground, thus potentially creating a fire-starting arc).

I also added a Lantronix UDS1100 terminal server to form an interface between the serial communication spoken by the Pentametric monitor and the ethernet protocol of the internets. As a result, I can query my system externally no matter where I am (once the home’s router is properly configured). I can also automate retrieval of the data logs twice a day (or more if I wanted) to guarantee that I do not lose any data (monitoring unit stores 1.3 days’-worth at 5 minute intervals). This way, I can disappear from internet access for days on end without losing knowledge of what my precious energy system is up to. My wife wants cat-cams to check up on our cats while we’re away. But I already have in place a way to check up on the PV system and on utility usage via TED—prompting my wife to question which I love more: our cats or my energy devices.  I’m smart enough to change the subject.

Eight panels on the garage roof, plus our old 64 W friend now tasked with pumping water in my rain catchment system.

What’s Next?

As far as my blogging duties are concerned, I still owe you an efficiency analysis of my PV system.  But for me personally, I’m pretty happy with my current PV setup.  I have gained valuable experience through the process of setting up the various stages of the system.  I have a system that can move with me wherever I go.  The PV system has helped me develop a keener awareness of wasteful energy practices.  I don’t have to worry about loss of refrigeration during power outages.  The door is open to expansion if I need it: I can always throw more panels on the roof or add batteries for greater capacity.  I can add circuits to my house to support more devices.

But mainly, having learned first-hand what it means to build, operate, and maintain a PV system has been hugely rewarding.  I’m pretty content with the current setup, and have no burning drive to grow further.  After all, we can’t expect growth forever.  At some point, it’s nice to sit back and enjoy the steady-state.

Warning: Do Not Try this at Home (Apparently)

A few readers have informed me that the 2011 NEC standards on PV installations have taken the DIY out of solar installations.  So doing what I did would now be against code, since I am not an authorized installer.  Even John Wiles, who wrote much of the NEC code is not authorized to install a system, and another individual who trains installers to take the test is not himself eligible to take the test, and could not today install the 7 kW system that he previously installed at his home.  So here I thought I was doing people a favor by providing information on how I did it myself.  Turns out you can’t.  Bummer.