One Year of Solar Panels

(Note: This post is a departure from the regularly-scheduled content of this blog.)

Today marks the one year mark of having our solar panels up and running, so I thought I'd post a quick update. (Technically, it's the one-year mark of having the monitor up and running, the solar panels were actually working for almost a week before that.)

After a full-year we've generated 6074 kWh of electricity and consumed 6371 kWh, so we've used 297 kWh more than we've produced. One of our two inverters broke last August so we were down one set of panels for about three weeks (you can see that reflected in the second graph below) until the new one came in and they could replace it. Based on how much we were generating in the months around that breakdown, my estimate is that if it hadn't broken it probably would've generated pretty close to that 297 kWh necessary for us to break even over the course of the year.

Once we got to April we pretty much stopped paying for electricity (it's still about $7 a month to be connected, though), except for August when we lost the inverter. With the shorter days we have currently we'll likely have some net kWh usage in January through March (so a small electric bill), and then go into positive territory for the rest of the year until December or so. Not too bad.

Tis the Season

Just like the last four years, I can't afford the postage to send this to all of you in my PLN. If you celebrate a holiday this time of year, then I wish you a good one. Thanks for all you do. And I wish all of you peace and happiness.

Solar Panel Update

Several people have asked for an update on the solar panels we installed. The panels were installed and became active in January (although our monitoring system didn't get activated until a week or so later, January 27th, so that's when all my easily accessible data will be from).

Overall, the system is performing well, even slightly better than expected. Here's a typical (sunny) mid-winter day:


And a typical (sunny) spring day:


A typical (sunny) day this week when it wasn't quite warm enough that we had the air conditioning on:


As you can see, we generated 20 kWh's more than we consumed.

And here's a typical (sunny) day when it was warmer, and we had the air conditioner on.


We didn't quite break even this day, but still not too bad.

Here's what the last month looks like:


And here's our total consumption versus generation since our monitor was installed on January 27th.

As you can see, we've generated more than we've consumed. For the past three months we haven't paid for any kWh's on our bill (although there is still a monthly fee to be connected to the grid). We'll probably continue to generate more than we consume through about September, maybe even October, then start dipping into that accumulated "bank" through the winter.

It's still too early to predict, but my guess is that we might finish our year with some still left in the bank. If that happens, they'll send us a check for the kWh's still in the bank, and then we start over again for the next year. (You can rollover your excess hours, which is better because when they send you a check it's at the wholesale price. But right now once you choose to rollover you can't ever change back, which means you'd never get "paid" for those excess hours that would keep accumulating if you generate more than you consume. We're waiting to see what a year or two looks like before deciding whether we want to switch to rollover.)

Overall, we're very pleased and would recommend anyone who's interested take a serious look at installing the panels (particularly if you live in Colorado, which is not only sunny, but has some decent incentives from our energy companies in addition to the federal ones).

Sometimes This Stuff Still Amazes Me

Just a quick post to note that I still find my own personal networked world to be pretty fascinating and amazing. Yesterday I was talking with my wife about a homework assignment Abby had in math where she needed to gather some data. So I threw together a quick Google Form, posted on my blog, and tweeted it out.

Very quickly the responses started coming in, mostly from Twitter I suspect because I doubt that many folks had seen the post at that point. (Next time I may add a question about where they found out about the survey just to confirm that.) About a day later we now have 299 responses (as of this writing) from 43 states and 18 countries (counting the U.S.). (You can see the results embedded in that post.)

Now this particular survey and this particular post are nothing earth-shattering, but it again reminds me of how different the world is from when I was growing up; how easy it is to connect with others around the world, and certainly how easy it is to gather data via Google Forms, a blog and Twitter. While I certainly still need to do a lot of thinking about how best to utilize this capability in meaningful ways, I think we all as educators need to be constantly asking ourselves the question, "What can we do now (that is relevant and meaningful for students) that we couldn't do before?"

Abby playing guitar for Grandma via Skype.

Be The Change

(Note: This post is a departure from the regularly-scheduled content of this blog.)

Here's the present we got ourselves this year.











It's not quite active yet, as we're waiting on the county to inspect it (hopefully next week), Xcel Energy to come out and switch out our meter with a net meter, and then Standard Renewable Energy can come out and flip the switch. With the rebate offered by our utility, and the Federal Tax Credit, SRE predicts we'll break even in about three years. (I think that's a little optimistic, as they assume a 10% increase in rates each year which I think is a little high, so I'm guessing it will be closer to four-and-a-half years.)

It's sized to provide between 95% and 100% of our electricity needs, although SRE says that most folks start reducing their usage once they have the real-time usage monitor in place (plus we installed a solar attic fan, which should reduce our air conditioning use, which will reduce our electric use further). We anticipate that as Abby gets older we'll start using a little more electricity, but we were shooting for about 100% of our needs. (Unless and until plug-in cars come along, in which case we could possibly add on to the system.)

If you live outside of Colorado, considering check with your local utility to see what incentives they might have (or contact SRE if they operate in your area). If you live in Colorado I'd suggest you contact SRE and they can provide you with information (whether your utility is Xcel or someone else). Xcel is currently in the process of reducing their level of rebates, but that is partially offset by the cost of the panels themselves continuing to decrease. The sooner you start, the higher your rebate and the sooner your break-even point is likely to be.

And, yes, we have one of these as well.


We've had it since April of 2006 and our lifetime miles per gallon is approximately 47.8.

Be the change you want to see in the world.

Update 12-23-09 (from 31,000+ feet - free wifi on the plane!): @ScottElias asked for some charts and graphs in the comments. Here you go (click on the images for a larger view). Once my system is up and running, I'll see if I can track historical info on usage and periodically post that as well. Note some of the assumptions they build in - like a 10% per year increase in electricity costs - which as I said previously I think is a little high, but this still gives you an idea.

Tis the Season

Just like the last three years, I can't afford the postage to send this to all of you in my PLN. If you celebrate a holiday this time of year, then I wish you a good one. Thanks for all you do. And I wish all of you peace and happiness.

Shift Happens Statistic of the Day 12-2-09

From the December 7, 2009 issue of Time Magazine:

In 1979, GM's U.S. employment peaked at 618,365. Today it's at 75,000 and falling fast. GM's U.S. market share, once about 50%, has fallen to about 20%.

That's about an 88% decline in U.S. jobs at GM in 30 years. Interestingly, it's only a 60% decline in market share, which illustrates the automation/productivity portion of the shift.


Flickr Photo Credit: two GM dealerships out of business, originally uploaded by marina.

How Many People in Your Family?

This post is more of just an extended tweet than it is a blog post, but I thought it might be interesting to share.

My daughter had a math assignment where she was supposed to gather data on how many people were in people's families, then graph it and determine things like median, mode, range, maximum and minimum (interestingly, not the mean, although they've done that for other problems - which is probably good since median makes much more sense for this problem). Just for fun I created a quick Google Form and tweeted it out.



The only required question was "How Many People in Your Family?" with some directions on how to define that for this problem, but then I also asked (just because I was curious) two optional questions: your location and your age.

Well, that quick tweet generated 95 responses (so far). Since Abby is at the point where it's still really hands-on with the data and you generate graphs by hand (to get a better understanding of the concept), that was a little more than she needed, so she decided to just use the first thirty-two. Here are her results:










In case you're curious, here are the results for all 95 data points:

The median and the mode were both 4 and the standard deviation was 1.54.

For those of you curious about the ages of the respondents, the mean was 40.37, the median and mode were both 39, and the standard deviation was 10.96. (It might be interesting for someone to do a more randomized survey of educational tweeters to see if anything could be deduced from the results - both age and family size data.) We had responses from all over the U.S., Canada, the United Kingdom, Australia and Thailand.

So, nothing profound here, but I just thought it was interesting in several respects. First, how many folks responded to a tweet that obviously was not going to have much benefit for/impact on them. Second, how easy it was to generate data via a tweet and a Google Form (not randomized, I realize, but still interesting). Finally, I found the age and family size of the folks who responded interesting, even if I can't draw any major conclusions from it. (Perhaps: The mostly educational twitterers who follow me and responded to this tweet are typically between the ages of 30 and 50 and have two to five people in their immediate family - not a huge surprise.)

Thanks to everyone that helped Abby with this assignment and, if you have anything more profound you can generate from this, feel free to leave it in the comments.

What's in a Name?

Update: The conversation continue here and here.