Solar John in Wyoming with Automatic Solar Shutters

On the way back from Denver we happened to stop at a Rest Area in Wyoming along I25.   The rest area is one of 19 solar rest areas that Wyoming built quite a while back.

South glazing on solar Rest Area in Wyoming

Placard showing all the solar features of the rest area.

The rest areas have bunch of solar features (see placard just above),  but the one that caught my eye was the fully automatic thermal shutters. 

The automatic shutters.

It has always been a bit of a problem in passive solar homes with lots of south facing glazing that while the south windows pick up a lot of useful heat when the sun is shining, they lose a lot heat when its not shining.  While there is normally still a good net gain even with the large night time losses, its still a big improvment in performance if some kind of insulating shade or shutter can be used to reduce heat loss at night.  The problem is that many people are just not up for raising and lower shades or shutters twice a day.

These very simple and automated shutters would be one way to take care of the problem.  The shutters apparently use a set of two cylinders to do the work.  One cylinder is mounted on the sunny side of the shutter and the other on the shady side.  The two cylinders are connected by a tube.  There is some fluid inside the system that partially fills one of the cylinders.  When the sun is shining, some of the fluid in the sun facing cylinder vaporizes which drives the rest of the fluid from the sun side cylinder to the shade side cylinder.  The shutters are carefully balanced with their center of gravity very close to the point the shutters pivot about.  So, the transfer of the fluid from the sun side to the shade sides shifts the center of gravity enough so that the shutter pivot open.  When the sun goes away, the opposite happens.   Simple and clever.

A few more pictures and details here... 

Have you got any ideas for automated window insulating devices?  -- please leave a comment.


Gary

Solar Heated Stock Tanks -- Reducing Drinking Opening Heat Loss

The solar heated stock tank project has been a good success with quite a few people building them and reporting good results. 

A solar heated stock tank.

The one remaining problem is that there is still a significant amount of heat loss out the drinking opening, and when you get extended periods of no sun and lots of wind and cold, there can still be enough ice accumulation to be a problem.   BUT, it looks to me like Art has worked out a good solution to this problem.

Art uses canvas awning material to make a sort of shield that reduces heat loss from the large open water surface down to just the area of the drinking hole itself -- see the pictures below.  Art reports that with this technique the tank can go several days of sunless, cold, and windy Wyoming weather without a problem.  Ice still forms in the drinking opening itself, but the horses can easily push the ice out of the way and get to the water -- the canvas is soft enough and slick enough that the ice does not freeze to it.

Using canvas shield to insulate the water surface.

Art's tank

More details...

Thanks very much to Art for sending this in!

Gary

Solar Powered Transporation for Disasters

I got a very interesting email from Terhesa about transportation in emergencies such as the earthquake in Japan.  She brought up some good points about the advantages of having a solar powered form of transportation for this type of disaster.

 

She pointed out that  the delivery and dispensing of gasoline depends on electricity at many stages.  This means that many of the people in the area effected by the Japan earth quake and similar disasters are unable to use their gasoline powered vehicles.  In some areas, it seems likely that this will be the situation for quite a while.

Most of us live in areas that are subject to natural or man made disasters that could result in extended periods without electricity, and since the gasoline delivery infrastructure depends on electricity, we would also be without the use of our cars.  In times of emergency, not having transportation could be more than an inconvenience -- for example not being able to evacuate a hazardous area. Having some form of independent transportation could also be very important for procuring supplies during an extended natural disaster.

Terhesa suggested that buying a solar powered scooter or bicycle not only gives you a good, low cost, green form of transportation for normal times, it also provides a means of transport that keeps working in case of disaster -- even extended disasters.  I think this is a great idea.


There are quite a few commercial and DIY electric vehicle projects listed here...

I like Electric-Bikes.com for a good rundown on the possibilities bikes to scooters to small E-Cars...

Gary

Improving the Efficiency of an Older Wood Burner

Scott has a 1981 wood burner that was built before the EPA regulations for wood burners came into effect.  The wood burner (like many others of that time period) is still in very good shape, but not very efficient.

Scott worked out a couple ways to improve the efficiency:

1- Adding an air supply to support secondary combustion.  This improves combustion efficiency and heat output, and reduces pollution.

The added air supply to support secondary combustion.

New piping to supply preheated air for secondary combustion near
the top of the firebox.

2 - Retrofitting a catalytic combustor which goes into the flue to burn the remaining burnable stuff in the smoke.  This also improves the combustion efficiency and heat output, and further reduces pollution.

Close up of the catalytic combustor (on right) and the bypass
damper to allow the cat to be bypassed.

Shows the new catalytic combustor installed just
above the stove in the flue.

Scott provides a lot of detail on how he built the two devices and also goes through a nice, simple and inexpensive way to measure wood burner efficiency with just an anemometer and a thermometer.

All the details on Scott's wood burner efficiency project...

More projects and information on wood burners and biofuels...


Gary

Giving LEDs a Try

We decided to give LEDs a try for our overhead kitchen lights -- thought I would pass on what we learned since some of it was not what we expected.

We had six overhead R30 track lights in the kitchen that we had converted from incandescents to CFLs  sometime back.  The CFLs worked out pretty well, but they did have a shorter life than you would expect from a CFL.  This is probably because the lights are turned off and on a lot, and that is not good for CFL life.  The lights are also very awkward to replace as the ceiling is 13 ft high, and its hard to get a ladder in the right place.  These are also the most used lights in the house, so that seemed like a good place to start.

Our new R20 track mounted LED lights.

We found that getting the right LED is a bit more complicated that just buying a bulb used to be.  The LEDs are expensive (as in $20 to $40 ish each), the quality is not yet consistent for all manufacturers (perhaps an understatement), and there are light quality and color issues that need to be understood.  And, given that the lights may last the rest of your life, you will live with any mistakes for quite a while.

The link below goes over all the details, but after some homework we were able to find a good LED for our situation, and we are very happy with the result.  The LED we selected is an R20 (instead of the R30's we had).  The new LED uses only 8 watts as compared to the 15 watt CFLs we had, which replaced the orginal 65 watt incandescents.  We also found that we could eliminate one of the lights.  So, we went from the original 390 watts in incandescents down to 90 watts of CFLS, and now 40 watts of  LED lights -- quite a saving -- about 500 KWH a year and over 800 lbs of CO2 compared to the original incandescent lights.

The R20, 8 watt LEDs we chose -- $22 each.

And, the lighting is very nice.  A definite improvement over the CFLs inspite of the fact that on paper the LEDs have substaintially less  total lumen.  In addition, the LEDs come on instantly, and I will never have to go up that ladder again!

The link below goes into some of the issues involved in finding the right LED and in deciding which of your current lights might be good candidates for replacement, and figuring out the dollar and carbon saving.  But, in a nutshell, it looks to us like at the current prices and performance the LEDs pay very well compared to incandescents, and also make sense as CFL replacements in some cases.

All the details on our first LED project...

Anyone have any interesting/helpful experiences in LEDs to pass on?

Light trivia -- did you know that the "R" in R20 means its a reflector light, and that the "20" means that the light diameter is 20 eighths of an inch (2.5 inches)?
An PAR38  is Parabolic Aluminized Reflector light that is 38*1/8 = 4.75 inches in diameter.
An A19 is the traditional Edison household light bulb shape that is 19*1/8 = 2.4 inches in diameter.

Gary

A $2K Solar Space and Water Heating System

We have been working on a very simple solar system that will do space heating and domestic water heating from the same system.  Its a very simple system that takes only regular DIY skills to build.  Nearly all the materials can be picked up at the local Home Depot type store, and the ones that can't have good online sources.

The collector for the new system

I've documented this system better than any other system on Build-It-Solar -- there are over a hundred pages of design and build information that should make it fairly easy to adapt the system to your situation.  There is also a lot of material on how stuff works and on other alternatives for each part of the system -- a bit of a text book on solar space and water heating.

Collector before painting.

We used twinwall polycarbonate glazing.

The system design is based on the $1K Solar Water Heating System that many people have built with good success.  It uses the same drain back collector system, and the same single large, vented to the atmosphere drain back tank.  It also uses the large coil of PEX heat exchanger for domestic water preheat.  The differences are that the collector is larger to provide extra capacity for space heating, the storage is larger, and there is a new system to distribute heat from the tank to a simple radiant floor loop.


The new radiant floor system just takes water from the top of the tank, pumps it through the floor loop, and returns it to the bottom of the tank -- no heat exchangers, no antifreeze -- just a little PEX tubing and a pump.

The new pump for the radiant floor loop.

We used a staple-up floor loop with insulation under.

This is the big coil of PEX that serves as the domestic water preheat heat exchanger.

The system is about as simple as you can get for a full four season, cold climate solar space and water heating system.  Simple is good (I think)  -- for airplanes or solar systems :)

It could (and should) be expanded with more collector area and more tank size to be able to do more space heating.  We would have added more collector area if we had the space for it on our south wall.  We do already have a dedicated solar space heating system, so this new one gets a part of the house not heated by the existing one.

The total cost of materials was a bit over $2000.  The system could be built for as much as $700 less, but we opted for "higher end" choices in the glazing, trim, and controller areas. 
I would estimate that the price for an equivalent commercially installed system would be north of $15,000  -- so the cost saving is significant.  Based on the 3 year payback for the $1K water heating system, I expect the payback for this system to be 3 to 4 years.


I'd very much like to hear any comments on how the writeup could be improved, or on things that are missing or not clear -- you can add a comment here or email me at gary@BuildItSolar.com

All the details on the new space + water heating system...


Gary

Plug in PV

Clarian is planning to come out with PV modules that can literally be plugged into the wall to make your own  grid-tied PV system.

The system consists of one or more 200 watt PV panels, each with a micro grid-tie inverter.  Each system also has a SmartBox for monitoring the system. 
The first 200 watt PV panel/micro inverters plugs into an regular wall plug.  Additional 200 watt panels panels plug into the first panel daisy chain style.    The SmartBox plugs into an AC outlet and (apparently) allows you monitor the system.

You can add several of the 200 watt panels -- each one is 60 by 40 inches.

They also have a 1000 watt unit with a "6 to 8 hour" installation time -- perhaps this needs a connection to the breaker panel, but I could not tell.

This looks like a very nice solution for people who want to get started a PV system without having to hire an installer -- it lets you start for less than $1000, and add to it from time to time.  The projected prices they show are competitive, and the unit is said to qualify for the federal 30% tax credit program.
They expect to have the units "in stores in 2011".


The micro inverter has all the usual safety features for not powering the grid when the grid is down to protect line workers.

The system also provides for monitoring your system from the web, again  similar to the Enphase systems.

While it seems like a very nice development, I do wonder about a few things:

• Will local utilities buy into the system -- normally, the utility would have to install a net meter to insure that you actually get credit for power you generate during times when you send power out to the grid.
• Basically the PV panel connects to the wall outlet via what amounts to an extension cord -- it seems like this might limit mounting possibilities and perhaps not look as neat as some might like (or not).
• PV panels are large and catch a lot of wind -- they need to be mounted carefully, and I could see people being a little too casual about this and losing expensive panels.
• I could also see people spending a couple thousand on this to save 60 KWH a month when the same $2000 spent on conservation and efficiency projects would save 500 KWH a month.

It will be very interesting to see how it all plays out.

The link to their website is: http://www.clarianpower.com/solar.html

Thanks to Gordon for sending in the note on this gadget!

Gary

Evaluating Ordinary Window Screen as a Solar Air Heating Collector Absorber

This is a chance to exercise your Physics brain a bit.

A few people have used a couple layers of ordinary window screen as the absorber for solar air heating collectors.  This is the same stuff you put in windows to keep the bugs out.
Scott and I have been doing some testing of air heating collectors of various types, and to the surprise of some, the collector that uses the two layers of window screen as the absorber has done as well or better (so far) as other more complex absorbers.

The way these collectors work is shown in the diagram -- air enters the collector via the bottom vent and is routed to the glazing side of the screen absorber.  The screen has a little bit of pressure drop and this tends to spread the air evenly over the screen.  As the air works its way through the screen, it is heated, and eventually makes it way out the top vent located at the top back of the collector behind the screen. 

In an alternative to this picture, it has been suggested by Laren over at the Yahoo SimplySolar group that the screen is really quite open, and that much of the sun passes right through the screen and ends up getting absorbed instead by the back wall of the collector.  In this view, the screen still helps, in that it does absorb some of the solar, but, perhaps more importantly, it keeps the heated air from migrating back to the cold glazing where heat losses would be high.

I did a little test to measure how much of the incident sunlight 1, 2 and 3 layers of fiberglass and aluminum screen absorb, and some tentative conclusions and some questions come out of this.  So, take a minute to look at the results and see if you have any ideas to contribute on making these absorbers more efficient -- or, maybe you think there is a better option altogether?

The Window Screen as a Solar Absorber Test Stuff...

Gary

New: PV pump for solar DHW, 3 day EV conversion, PV system sizer

Just a few new content items on Build-It-Solar:

TOPSFLO PV powered pump for solar water heating systems:
This is a new and very low cost pump that is intended for circulating water in solar water heating systems.  Its a DC pump and is designed to be driven directly by a small PV panel.

It has a startup head capability of about 9 ft, and a nominal flow rate of about 2 gpm -- good for 60+ sqft of collector area.  It is also good for temperatures up to 200F and has automatic shutdown for higher temperatures.  Its a brushless design and should provide a long life.  But, it is new, so I suppose there is a bit of buyer beware.
http://www.builditsolar.com/Projects/SpaceHeating/Components.htm#TOPSFLO 

Thanks to Rodney for sending in a note on this.


Gas to Electric Car Conversion in 3 Days!
This is an interesting project that took on converting a small gas powered Daihatsu Charade in a weeks time -- they actually managed to do it in 3 days!

They did quite a nice job of documenting the whole thing including a very nice video that gives a good feel for what's involved in a EV conversion.  I suppose its only fair to say that there were as many as 10 of these guys working on the car at once -- it might take one of us a bit more than 3 days.

http://www.builditsolar.com/Projects/Vehicles/vhehicles.htm#3DayEV

PV System Designer
This is a handy calculator to get several alternative actual system definitions based on your available PV panel area, climate, and power range you are interested in. 

It will pick several alternative actual systems based primarily on lowest price.  The definition includes specific PV panels and a specific inverter with prices, but does not include other details that make up the system -- so, there are still a lot of things to add to get to a full system.

http://www.builditsolar.com/Projects/PV/pv.htm#PVPowerCalculator

-------------------------
Getting close to putting up the detailed how-to on our new, simple, solar water + space heating system -- maybe Monday.


Gary Feb 12, 2011

The Peel P-50 -- A Really Small Car

The Peel P-50 is officially certified as the world's smallest car by Guiness.

Passenger capacity 1 (plus one shopping bag).
Doors 1.
Wheels 3.
Displacement 50 cc.
Empty Weight 130 lbs.
Fuel Efficiency 100 mpg.

Described in this CNET article and in the very amusing BBC video...

Judging by the video it might benefit from outriggers and some pollution controls.