Hanlon’s Razor and Online Comments

Never attribute to malice that which is adequately explained by stupidity. – Hanlon’s Razor


Boy, but sometimes it is hard.  There was a recent article in the local paper about a solar manufacturing plant going up on Minnesota’s Iron range.  And you can bet that any article about alternative energy will bring out the interesting comments in droves.  (Maybe this is true about any article about anything?)  Warning: If you don’t want a boring rehash of anti-solar comments and my attempts to bring a few factual nuggets to the conversation, you should stop reading this post now.  You have been warned… Continue reading

3MWh and counting …

We hit 3MWh (that’s megawatt-hours) of solar PV production yesterday, a few weeks ahead of the 1-year anniversary of the install.  In that time, we:

  • Generated 3000 kWh
  • Pushed 1877 kWh onto the grid
  • Pulled 3278 kWh off the grid

So, that means we used (3000 – 1877 + 3278) = 4401 kWh in that time (for about 360kWh/month average), and we generated 3000 / 4401 = 68% of the electricity we used in our home.  A bit shy of the 75% I’d hoped for but not too bad!

The monetary value of those 3000MWh is about $300 here in MN, at about $0.10/kWh (my baseline for comparison is the cost for electricity with Windsource, since we have subscribed to that program for many years now.  It’s only slightly higher in cost, about $0.009/kWh, since the fuel charge gets removed for Windsource customers).

In Praise of Solar (and Wind) Powered Beer

ft_carbon_footprintIs it something in the water?  Or maybe the hops… I keep coming across more breweries really going the extra mile to produce their product in a sustainable manner.

The first one I knew of was New Belgium Brewery, makers of Fat Tire and other fine brews.  As the story goes, “In 1998, a unanimous vote by employee owners switched New Belgium to wind power. The first wind powered brewery in the United States, thank you very much.”  They’ve made other strides towards efficiency & sustainability, as documented in their sustainability blog.

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Solar Growth


I asked the folks at Enphase if they had data on the total output of their installed systems over time (which report back statistics via a buy-back-your-data sort of subscription arrangement)  This is what they came back with.  Pretty impressive growth, whether it reflects overall solar growth or growth of this one company’s installations!  Almost 5 gWh in Sept 2010 is nothing to sneeze at.  Most must be in the northern hemisphere, you can see the seasonality of power production start to kick in….

Other neat visualizations of Solar PV growth in the US can be found NREL’s OpenPV site.

Solar Monitoring

Solar Monitor ScreenshotWhile the Enphase Enlighten monitoring site is pretty swanky, it’s slow to load and extremely flash-heavy.  It has the advantage of being able to do per-panel monitoring, event log monitoring, etc, but I was hoping for something a little more lightweight.  Enter pachube.com.  Let’s build out the internet of things….

The Envoy system monitor for the Enphase inverters has very basic output monitoring abilities; it shows you current power, and daily, weekly, and lifetime energy production.  So, we can screen-scrape this and upload it to pachube, then do what we like with the data.

I have this script on a 5-minute* 10-minute cron job to get the data.  The Envoy doesn’t seem to update faster than 5 minutes, and it’s such a gutless wonder, doing it any more often than that brings it to its knees, and it stops updating the main site!  If you have problems, you may want to reduce the updates to 15m or more.

To use the script, first get a Pachube API key, and set  up a new Pachube feed.  Add 4 datastreams, for instantaneous power, daily production, weekly production, and lifetime production, in that order.  Edit the script to add your envoy hostname/IP, your API key, and your feed ID.  Then put the script on a 5-minute cron job.  You’ll start seeing the data on a Pachube feed page like this.  Then you can use some of the apps highlighted on apps.pachube.com to create widgets as in the image above, as seen on this page.  You can even get an iPhone app to monitor the data, or create an OSX dashboard widget from the HTML objects!

*Edit: Don’t set the cron job to be more frequent than 10 minutes.  I’ve had trouble with the Enovy unit bogging down and not reporting to Enlighten if you hit it more than every 10 minutes (!)

At last: Solar is running


I got the meters installed today.  It took about 2 minutes of work, after 2 weeks of wait.

The meter on the left is the “production” meter which measures how much power the panels have made over their lifetime, period.  It’s so the utility knows what they got for their rebate money.  (Oddly, it’s the exact same Centron C1SC meter I had previously, for usage measurements!)  The meter on the right is the net meter.  Today it’s running backwards, even though it’s cloudy, because the house is pretty much at base load.

All that’s left is the anti-islanding inspection*, but my installer tells me the utility is OK with having them on prior, so we’re up and running!  On a cloudy day, of course.

I don’t yet have the official Enlighten URL for the array, but my homebrew monitoring is here on pachube.com.

*And one concern about the physical install of the panels & cables, which might possibly require removal and re-fastening of the panels, which would just be awful at this point.

Edit: The official monitoring site is now active.