Archive for July, 2011

Green as a National Park

Solar Panels in Denali Visitor CenterWill and I were lucky enough to travel to Alaska last month with his family and visit several amazing national parks.  Denali was probably the coolest (grizzly bears!  caribou!  huge mountains!) but I also was super impressed by the Kenai Fjords National Park with its coastal glaciers.  It’s pretty humbling being next to a giant river of ice and to watch an immense chunk break off with a loud “CRACK” and fall into the ocean.  Amazing.

While we loved the wildlife and the beautiful landscapes, we also enjoyed seeing all the ways the parks strive to be green, including quite a few renewable energy technologies.  It seemed like every building (even the outlying bathroom structures) had a solar panel on it.    Eielson Visitor Center, deep into the tundra of Denali National Park and with spectacular views of Mt McKinley, was the most impressive and is a LEED platinum building.  It’s essentially built into a hill with tundra plants growing on the roof to help it blend even further into the landscape.  One of their challenges (and motivations) is that there is no electric grid available 66 miles into the park.  So, the building uses several different energy sources (solar panels, hydroelectric generator in a nearby stream, and small propane generator) and was designed for maximal passive heating and lighting.  One advantage they have is that the center is only open for four summer months (June – September) because it is snowed in the rest of the year.

We happened to visit on the summer solstice, when the official sunrise was at 3:45 AM and official sunset was at 12:21 AM the next day (a 20 hour 36 minute day) but it never got truly dark –  just dusk-like.  You can generate a lot of electricity from solar panels on a sunny day in that part of the world!  However, they also have a lot of cloudy days so it has been an experiment to see how solar electricity and solar hot water work for the center.  I think it’s awesome that the parks are able to try out different technologies and do the best they can to have a minimal impact on some of the best natural landscapes in our country.

Electric Car for RangersIn Kenai Fjords, I snapped a quick picture of an electric car driven by the rangers.  I expect it makes a lot of sense for traveling between their two visitor centers that are about fifteen miles apart over flat paved roads (as opposed to driving through the backcountry).  We are still intrigued by the idea of getting an electric car for our household since so much of the driving we do is short distances on city streets with low speed limits.  However, it doesn’t look like it will bubble up to the top of the priority list anytime soon.  I guess we’ll let the parks work out all the kinks and then we’ll adopt the refined version.

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One Step Closer to Solar Electric Panels

Solar Pathfinder Reading of Our RoofThe good folks at SIREN gave a stirring presentation last month about how now is the time to switch to solar electricity.  Panel prices have fallen significantly due to the recession, electricity prices look poised to raise (at least here in Indiana where Duke Energy is spending several billion dollars to construct a coal gasification plant in Edwardsport and pass costs on to customers), and there’s a brisk market for renewable energy credits.  We had already caught the fever a bit and the talk just convinced us it was time to get an actual site assessment and cost estimate.

We’re working with Alex Jarvis of Solar Systems of Indiana, a quirky guy who knows a heck of a lot about solar.  He came out to discuss some different options and to do a site reading of a few potential spots using his handy dandy Solar Pathfinder.  It’s a very simple little device that maps shade to determine if a particular spot has a good solar window.  The image above is from the middle of our roof, which has a very good solar window of about 85% between the key sunshine hours of 9:00AM and 3:00PM – solar time.  (See rant on Daylight Savings Time below.)

pole-mounted-solarHe also measured a few other spots in our yard so we could think about doing a pole-mounted solar panel.  You could argue that the pole-mounted systems are a little on the ugly side but they are very practical in terms of maintenance – no climbing on the roof, no trying to patch the roof under the solar panels – and they are great for houses that have a shaded roof but sunny yard.  We are leaning in that direction simply because our roof is 20 years old and will need to be replaced well before the solar panels.  Alex actually has his panel (shown at right) configured so he can move it around during the day to maximize its exposure to direct sunlight and therefore maximize electrical generation.  He is the first to admit that is way too hardcore for most people but he is a tinkerer and enjoys fiddling.  Most people just retilt their panels twice a year at each solstice.  At the spring solstice, the panel is tilted closer to horizontal since the sun is higher in the sky during the summer.  At the fall solstice, the panel is tilted more vertical since the sun is low in the sky during the winter.

After that is the decision of what kind of solar panels and inverters to get, which I must confess is mostly Greek to me but Will is drooling a bit at the thought of enphase microinverters that broadcast all kinds of exciting data for him to analyze with a fine-toothed comb.  We’re looking at getting six modules that are each rated somewhere around 240 watts, giving us a system that is around 1.44 kilowatts.  Here in southern Indiana, we average about 4.7 hours of direct sunlight per day once you factor in cloudy days and the fact that our days are significantly longer in the summer but shorter in the winter.  In a perfect world, our solar panels would produce 6.8 kw-hr per day (1.44 kw x 4.7 hours) or 2,470 kw-hr per year.  However, there are some losses that we have to take into account with our lovely fudge factor friend, the derate factor.   The derate factor has several components:

  • Shade on our system.  Our solar window is about 85% open, 15% shade.
  • Losses from the inverter, connections, and wiring
  • Losses from dirty solar panels (we’re going to assume we can keep ours clean – with a hose if needed)
  • Losses from improper angling (again, we’re in good shape with a pole-mounted system that can be tilted at least twice a year)

In the end, we figure our derate factor is about 0.8 (meaning we lose about 20% of the ideal production level), which reduces our expected output to about 5.4 kw-hr per day or 1,970 kw-hr/year.  That should still just about cover our needs and in our area it’s not worth overproducing since the electric company will just keep rolling over our credits until we move.  If you’d like to try this game at home, check out the PV Watts calculator developed by the National Renewable Energy Lab.  Soon we should have some prices to go along with our power estimates but for now we’re excited about the possibilities and also trying to brainstorm how we might landscape our yard to make the solar panels blend in a bit.  Any and all suggestions are welcome!

Daylight Savings Time Rant:  Indiana only recently adopted Daylight Savings Time while staying in the Eastern Time Zone, and I am not a fan.  Today the sunrise was at 6:30AM and sunset at 9:15PM, which means our solar noon is really about 1:50PM and our key sunshine hours are 10:50 to 4:50.  It also means that the fireflies don’t come out until 10:00 and it’s awfully hard to schedule fireworks, bonfires, or drive-in movies that children (or I) can stay awake for.  I liked it better when we were in straight-up Eastern Standard Time and never had to worry about changing our clocks.

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