Elektra One Solar Airplane

Being an old airplane guy, I though this development in solar airplanes was really interesting.

The Elektra One Solar from PC-Aero is a single place, electric airplane with a maximum range of 1000 km.  While flying, it is about half powered by solar cells mounted on the wings and tail.

The empty weight is only 100 kg -- it is constructed mostly from carbon fiber.

There is also a 2 place version.

Seems like solar powered airplanes may be coming out of the extreme experimenter class into something more interesting to regular small airplane users?

Makes you wonder what an electric, aerodynamic, 100 kg car with solar cells could do?

All the details...

Gary

A 2 Year Update on Gordon's Unique Khanh Solar Water Heating Collector

A couple of years ago Gordon did a solar water heating collector for his home that uses the Khanh design.

This design improves the performance of conventional water heating collector by extending the area of the collector to include an air heating collector that warms the area around the water heating collector to reduce heat losses from the water heating collector.

The design is explained in detail in Shurcliff's book: New Inventions in Low-Cost Solar Heating

Gordon's original article on his implementation of the design along with construction details is here..

Its been two years and Gordon has a good report on the things that worked and the things that did not work so well and had to be fixed or improved.

The report covers: performance, a new differential controller, pumps, backup water heaters, and some plumbing issues.... 

All good stuff to know if you plan to use this design.

Gary
March 31, 2013

Rain Water Collection -- Year Two Update -- Freeze Problem

Our 2200 gallon rain water collection system has been working well, but we did have a freeze damage problem this winter.

The full rain water system is described here...

This winter the first flow diverter reservoir managed to fill up with water and freeze over the winter.  The expanding ice did an impressive job of breaking the large PVC pipe that serves as the reservoir.  The valve at the bottom of the reservoir was open for the winter, but must have plugged up and allowed water to accumulate.

Freezing water breaks the pipe that serves as first flow diverter.

For now, I've just removed the first flow reservoir where it threads into the collection plumbing and put a threaded PVC plug in to make the system functional, but with no first flow diverter.  Will need to work out a better system that is less subject to freeze damage.

A PVC threaded plug replaces first flow reservoir for now.

More details on the 2nd year of operation here...

Gary

Renewable Energy Magazine Article on DIY Renewable Energy

Richard Crume's latest blog for Renewable Energy Magazine is about the DIY area of renewable energy.  I'm happy to say the article features Build-It-Solar.

Richard describes some of the rewards of doing DIY renewable energy projects, and some of the achievements of the the DIY crowd.

One of the Richard's projects that is featured on our Solar Homes section is this article describing the this very energy efficient and very nice to live in house they built.

Gary

Adding Glazing to the Off The Shelf Solar Water Heating System Collector

This is an update on the project to develop a simple, efficient, low cost and reliable DIY solar water heating system that is easy to install because it uses all off the shelf parts.

The system uses an unglazed pool heating collector because it is inexpensive, easy to install, and allows the system to qualify for the federal tax rebate.  The performance of this collector is good for warm and moderate climates, but falls down during the winter in cold climates.

This update covers adding glazing to the pool heating collector to improve its performance when when its cold and for part sun conditions.

The pool heating collector with glazing.

The glazing used is SunTuf corrugated polycarbonate, which was chosen because it is tough, long lived, readily available (eg Home Depot), and has a high service temperature.  The glazing is supported by a simple frame that just plunks down over the collector -- the weight of the glazing assembly is supported by the collector manifold, and the glazing assembly is held down by a couple of straps in the same way the the collector itself is held down.  The whole glazing assembly for the 4 by 10 ft collector is light weight and can be handled by one person.

The glazing includes some openings at the bottom and at the top that allow a controlled amount of air to circulate between the glazing and the absorber.  This is to mellow out the temperature that the collector gets to if the collector is stagnated (no water flow).   The idea is to keep this air flow small enough to not significantly effect collector performance, while at the same time keeping stagnation temperatures within bounds.

The link below gives all the details on the construction.

The performance of the system is definitely improved with the glazing in place.  For some conditions that are typical of moderate to cold climates, the improvement is of the order of 50% in heat output.
The link below gives complete performance details, and compares the performance of the glazed and unglazed pool heating collector to commercial flat plate and evac tube collectors on both heat output and heat output per dollar of collector cost.

Comparing efficiency of several collectors to our collector.

All the details on the updated collector with glazing...

The main page for the Off The Shelf DIY Solar Water Heating System....

Comments, suggestions, questions are most welcome.

Gary
March 17,2013

ASES Solar Citizen Program

ASES (American Solar Energy Society) has been been working for more than 50 years to bring about a transition to solar and renewable energy in the US.

ASES has started a new program called the Solar Citizen that is aimed at providing families with the information and tools needed to get their own solar energy projects going.

"We know that most Americans would produce their own clean local energy if it were easy and affordable. We don’t tell you why you should want it. We tell you ­how to get it. We show you who figured it out, and how they did it. We connect you to news and tools to help make it happen on your home, in your town, on your farm, on your church, or on your school."

The latest addition of the Solar Citizen Newsletter "Do-It-Yourself Solar", provides some good information and links for DIY projects and information.

I think its great to see ASES concentrating on helping families get the practical information and tools they need to get solar projects done, and in particular the interest in DIY projects.  Please let them know you think this is a good direction.

Sign up for the Citizen Solar Newsletter....

Also, have a look at these ASES offerings:

• Solar Today magazine -- very good magazine on solar and renewable energy
• The annual ASES conference -- papers and workshops on the latest in solar -- this year in Baltimore
• The National  Tour -- a fall tour of solar homes  in your area

ASES would love to have you post your solar or renewable energy projects on their Facebook Page...

Gary

A Inexpensive DIY Blower Door That (pretty much) Does It All

This project will tell you how to build a pretty good blower door for about $30. 

You can use this Blower Door to: 

• Find air infiltration leaks into your house
  
•  Trace your progress in sealing the house,
  
• Estimate your infiltration flow at 50 Pa (a blower door standard) and compare it to other homes.
  
• Estimate your heat loss due to infiltration, and compare it to other heat losses.
  
• Estimate fuel saving and CO2 reduction from air sealing your home. 

It basically does what a commercial blower door does, but less automatically and less accurately.  Also makes one helluva ventilation fan.

The furnace blower  blower door  mounted in window with
pressure gage to right.

The blower door is a large fan that is installed in a door (or a window for the DIY one).  The fan forcefully blows air out of the house, which increases the inflow of air through all the cracks in your house that let air in.   This increased flow makes it easier to find the leaks and seal them up.

In addition, the blower door fan can be set up to measure the flow rate out of the house when the pressure difference between the inside and outside of the house is 50 Pa.  This is a standard test that has been done on many homes, so you can see how your house tightness stacks up to other homes.  

In addition, the flow out of the house with a  50Pa house depressurization can be used to estimate the natural infiltration for your house, and this can easily be used to estimate the heat loss, furnace fuel, and CO2 emissions associated with your homes infiltration.

So, basically, a blower door helps you find and seal leaks, tells you how tight your house is compared to others, and lets you figure out the heat loss and furnace fuel that go with the infiltration.   Everyone should have one!

The blower door on its mounting board with the
speed selection switches.

The homemade blower door can do all of these things -- albeit with a bit less accuracy and a bit more work than a "real" blower door.   

The extensive writeup provides all the details on building the blower door, installing it, using it, and all of the infiltration flow calculations so you can calculate the tightness and infiltration heat loss for your house.

The inexpensive 0 to 50 Pa pressure gage for measuring house
depressurization

All the details on building and using the homemade blower door...

A real deal commercial blower door.

Gary February 26, 2013

Choosing Insulation -- a talk by Alex Wilson

This is a talk by Alex Wilson on essentially all of the insulation products used in home construction.

The talk covers the environmental effects in depth, and also gets into some of the usability aspects for different applications.

Some of the most common insulating products (eg Extruded Polystyrene) have some very serious greenhouse gas impact and should be avoided where possible.

The talk is hosted on the Building Green site and there is no charge -- I don't know how long the video will be offered.

This is the link to view the video...

Gary

A Prototype Dryer Heat Recovery Heat Exchanger

I did a first cut prototype of a heat exchanger that extracts heat from our clothes dryer exhaust and uses the recovered heat for space heating.  So, this is a brief description of the prototype followed by some questions dealing with how to make it more efficient.

This is just a prototype -- its made out of scrap material I had on hand.  I wanted to investigate what the real heat recovery potential is and to see how bad potential problems such as lint, water, excessive pressure drop might be.

This is a picture of the made from scrap heat exchanger.

It is a stack of 14 twinwall polycarbonate glazing panels that are spaced apart by 1/4 inch.  The dryer air (red and blue arrows above) flows up through the spaces between the twinwall sheets and the room air (green arrows) is drawn in by the fan on top and pushed down through the cells in the twinwall.  This provides about 130 sf of heat exchange area.

The plot above shows a log of heat exchanger inlet and outlet temperatures for the two flows for a good sized load of laundry.

In its current state, it works pretty well.  At the marked location dryer air enters at 136F and exits at 88 F, and the room air enters at 79F and leaves at 95 F.

The recovered heat is equivalent to about 32% of the electricity that the dryer uses to do the load.  There are a few simple changes that might improve this that are discussed at the details link below.  So, not so bad for a first try?

Pressure drop through the exchanger is low and does not affect dryer operation.  Lint is near non-existent so far, and appears to be a very workable problem.

Oddly, very little water or condensation is produced.  The pictures in the details link below show what happens -- basically just a little fog in places and a drop or two.  This is a good news - bad news thing.  Good in that less water will be easier on the exchanger materials, but bad in that the heat used to evaporate the water in the dryer is not being recovered, and this is about half of the heat.


It dawned on me that if the exchanger could be changed so that it condensed out most of the water in the dryer airstream, then 1) you recover the heat that was used to evaporate the water, and 2) you could likely vent electric dryers inside (with a good lint filter).

The number 2 item is a big one in that it prevents the dryer from pulling in outside air that needs to be heated by your furnace.  On cold winter days, this can be about as much energy as the dryer uses in electricity.

By my numbers, a dryer/heat exchanger set up to do the above could save 80% of the total (electric + HVAC) energy used.  This would be a 1000 KWH saving per year for some families.

Homework:
So, if you have a moment, please look over the details link below and see if you can figure out: 1) why the current version condenses out so little water, and 2) what could be changed to condense out a large fraction of the water in the dryer exhaust.

All the details on the dryer heat recovery heat exchanger...


-------------
This is a good paper that covers the incredible amount of energy wasted in clothes drying and gives a good picture of how dryers work and some potential improvements...

Thanks,

Gary

South Wall Solar Space Heating System

This is a really nicely done solar heating project that uses solar water heating collectors integrated with the south wall for space heating.

The solar south wall.

The collector frames are site built and nicely blended into the wall.  The absorber plates were bought from SunRay.

The heat distribution system uses PEX floor loops stapled up to the bottom of the floor.  This is the nice simple manifold for the radiant heat.

The system includes removable reflectors to increase performance.  This kind of reflector is particularly effective in the late spring and early fall when the sun is getting higher and collection is dropping off, but you still need some space heating.

Reflectors have the advantage that they increase solar collection without increasing glazing heat loss.

All the details on Jim's site ...

Recent additions to the system include adding a wood stove  which is interconnected the solar heat storage tank for additional heat.   Jim is also working on a live data reporting system.   A writeup on these will likely be added this summer, so stay tuned.

From Jim -- "I have not turned my furnace on in two years."

Thanks to Jim for taking the time to carefully document the system!

Gary Feb 1, 2013